Showing 1–50 of 94 results for author: Hsu, S

Ubiquity of Methanol and its related Chemical Segregation in Orion Starless Cores: the ALMASOP Sample

Authors: Shih-Ying Hsu, Sheng-Yuan Liu, Xunchuan Liu, Pak Shing Li, Ken'ichi Tatematsu, Naomi Hirano, Sheng-Jun Lin, Kee-Tae Kim, Shanghuo Li, Tie Liu, Dipen Sahu

Abstract: Complex organic molecules (COMs) in starless cores provide critical insights into the early stages of star formation and prebiotic chemistry. We present a chemical survey of 16 starless cores (including five prestellar cores) in the Orion A and B molecular clouds, targeting CH3OH, N2H+, CCS, and c-C3HD, using the Atacama Compact Array (ACA) and the Yebes 40-m telescope. CH3OH was detected toward a… ▽ More Complex organic molecules (COMs) in starless cores provide critical insights into the early stages of star formation and prebiotic chemistry. We present a chemical survey of 16 starless cores (including five prestellar cores) in the Orion A and B molecular clouds, targeting CH3OH, N2H+, CCS, and c-C3HD, using the Atacama Compact Array (ACA) and the Yebes 40-m telescope. CH3OH was detected toward all targets, confirming its ubiquity in starless cores, consistent with previous surveys in Taurus and Perseus. ACA imaging shows that CH3OH, CCS, and c-C3HD generally trace the outer layers of the dense cores outlined by N2H+, each exhibiting distinct spatial distributions. Meanwhile, Comparison with Yebes data reveals an extended, flattened CH3OH component. CCS and c-C3HD tend to be detected or non-detected together across cores, while cores near dust-rich regions on a large scale often lack both, suggesting environmental influences linked to the interstellar radiation field. Within individual cores, CCS typically resides in an outer layer relative to c-C3HD. Our findings underscore the importance of high-resolution studies for understanding the origins and spatial differentiation of COMs and carbon-chain molecules in cold, quiescent environments. △ Less

Submitted 29 November, 2025; originally announced December 2025.

Comments: 36 pages, 6+16 figures

Search for planetary-mass ultra-compact binaries using data from the first part of the LIGO--Virgo--KAGRA fourth observing run

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1743 additional authors not shown)

Abstract: We present a search for gravitational waves from inspiraling, planetary-mass ultra-compact binaries using data from the first part of the fourth observing run of LIGO, Virgo and KAGRA. Finding no evidence of such systems, we determine the maximum distance reach for such objects and their merger rate densities, independently of how they could have formed. Then, we identify classes of primordial bla… ▽ More We present a search for gravitational waves from inspiraling, planetary-mass ultra-compact binaries using data from the first part of the fourth observing run of LIGO, Virgo and KAGRA. Finding no evidence of such systems, we determine the maximum distance reach for such objects and their merger rate densities, independently of how they could have formed. Then, we identify classes of primordial black-hole mass distributions for which these rate limits can be translated into relevant constraints on the mass distribution of primordial black holes, assuming that they compose all of dark matter, in the mass range $[10^{-6},10^{-3}]M_\odot$. Our constraints are consistent with existing microlensing results in the planetary-mass range, and provide a complementary probe to sub-solar mass objects. △ Less

Submitted 5 December, 2025; v1 submitted 24 November, 2025; originally announced November 2025.

Comments: 6 pages (main) + 7 pages (appendix) + refs; 8 figures

Report number: P2500248

ALMASOP: Inner-Envelope Structures of Protostars Driving Nascent Jets

Authors: Somnath Dutta, Chin-Fei Lee, Naomi Hirano, Doug Johnstone, Kee-Tae Kim, Yi-Jehng Kuan, James Di Francesco, Kenichi Tatematsu, Mika Juvela, Chang Won Lee, Alessio Traficante, Vivien Huei-Ru Chen, Manash Ranjan Samal, David Eden, Dipen Sahu, Shih-Ying Hsu, Tie Liu, Sheng-Yuan Liu

Abstract: Protostellar jets provide valuable insight into the evolutionary stage and formation history of star-forming cores in their earliest phases. We investigated the inner envelope structures of three extremely young protostars, selected for having the shortest dynamical timescales in their outflows and jets. Our analysis is based on Atacama Large Millimeter/submillimeter Array (ALMA) observations of t… ▽ More Protostellar jets provide valuable insight into the evolutionary stage and formation history of star-forming cores in their earliest phases. We investigated the inner envelope structures of three extremely young protostars, selected for having the shortest dynamical timescales in their outflows and jets. Our analysis is based on Atacama Large Millimeter/submillimeter Array (ALMA) observations of the N2D+, DCO+, DCN, C18O, CH3OH, and H2CO lines, along with 1.3 mm continuum data, obtained at two spatial resolutions of ~500 AU and 150 AU. By examining molecular depletion and sublimation patterns, emission extents at core-scale and outflow rotational temperatures, we assessed the relative evolutionary stages of the three sources. In G208.68-19.20N1, the absence of N2D+ toward the core-despite a semi-ring-like distribution-and the presence of bright DCN and DCO+ emission cospatial with C18O indicate a warmer envelope, possibly suggesting a more advanced evolutionary state. In contrast, G208.68-19.20N3 shows no dense central structures in C18O, DCN, DCO+, or N2D+, with emission instead appearing scattered around the continuum and along large-scale filaments, consistent with a likely younger stage than G208.68-19.20N1. The third source, G215.87-17.62M, exhibits compact C18O emission at the continuum peak, but spatially extended N2D+, DCN, and DCO+ along the continuum, pointing to a cooler envelope and likely the youngest stage among the three. This comparative analysis across three protostars demonstrates the effectiveness of molecular tracers for evolutionary staging, though variations in luminosity or accretion may also shape chemical morphologies. These results highlight the promise of broader surveys for advancing our understanding of early protostellar evolution. △ Less

Submitted 7 November, 2025; originally announced November 2025.

Comments: 19 pages, 8 Figures. The paper has been accepted for publication in The Astrophysical Journal (ApJ)

Direct multi-model dark-matter search with gravitational-wave interferometers using data from the first part of the fourth LIGO-Virgo-KAGRA observing run

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1745 additional authors not shown)

Abstract: Gravitational-wave detectors can probe the existence of dark matter with exquisite sensitivity. Here, we perform a search for three kinds of dark matter -- dilatons (spin-0), dark photons (spin-1) and tensor bosons (spin-2) -- using three independent methods on the first part of the most recent data from the fourth observing run of LIGO--Virgo--KAGRA. Each form of dark matter could have interacted… ▽ More Gravitational-wave detectors can probe the existence of dark matter with exquisite sensitivity. Here, we perform a search for three kinds of dark matter -- dilatons (spin-0), dark photons (spin-1) and tensor bosons (spin-2) -- using three independent methods on the first part of the most recent data from the fourth observing run of LIGO--Virgo--KAGRA. Each form of dark matter could have interacted with different standard-model particles in the instruments, causing unique differential strains on the interferometers. While we do not find any evidence for a signal, we place the most stringent upper limits to-date on each of these models. For scalars with masses between $[4\times 10^{-14},1.5\times 10^{-13}]$ eV that couple to photons or electrons, our constraints improve upon those from the third observing run by one order of magnitude, with the tightest limit of $\sim 10^{-20}\,\text{GeV}^{-1}$ at a mass of $\sim2\times 10^{-13}\text{ eV}$. For vectors with masses between $[7\times 10^{-13},8.47\times 10^{-12}]$ eV that couple to baryons, our constraints supersede those from MICROSCOPE and Eöt-Wash by one to two orders of magnitude, reaching a minimum of $\sim 5\times 10^{-24}$ at a mass of $\sim 10^{-12}$ eV. For tensors with masses of $[4\times 10^{-14},8.47\times 10^{-12}]$ eV (the full mass range analyzed) that couple via a Yukawa interaction, our constraints surpass those from fifth-force experiments by four to five orders of magnitude, achieving a limit as low as $\sim 8\times 10^{-9}$ at $\sim2\times 10^{-13}$ eV. Our results show that gravitational-wave interferometers have become frontiers for new physics and laboratories for direct multi-model dark-matter detection. △ Less

Submitted 11 December, 2025; v1 submitted 30 October, 2025; originally announced October 2025.

Comments: 9 pages, 1 figure (+1 figure in appendix)

Report number: P2500252

GW241011 and GW241110: Exploring Binary Formation and Fundamental Physics with Asymmetric, High-Spin Black Hole Coalescence

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1761 additional authors not shown)

Abstract: We report the observation of gravitational waves from two binary black hole coalescences during the fourth observing run of the LIGO--Virgo--KAGRA detector network, GW241011 and GW241110. The sources of these two signals are characterized by rapid and precisely measured primary spins, non-negligible spin--orbit misalignment, and unequal mass ratios between their constituent black holes. These prop… ▽ More We report the observation of gravitational waves from two binary black hole coalescences during the fourth observing run of the LIGO--Virgo--KAGRA detector network, GW241011 and GW241110. The sources of these two signals are characterized by rapid and precisely measured primary spins, non-negligible spin--orbit misalignment, and unequal mass ratios between their constituent black holes. These properties are characteristic of binaries in which the more massive object was itself formed from a previous binary black hole merger, and suggest that the sources of GW241011 and GW241110 may have formed in dense stellar environments in which repeated mergers can take place. As the third loudest gravitational-wave event published to date, with a median network signal-to-noise ratio of $36.0$, GW241011 furthermore yields stringent constraints on the Kerr nature of black holes, the multipolar structure of gravitational-wave generation, and the existence of ultralight bosons within the mass range $10^{-13}$--$10^{-12}$ eV. △ Less

Submitted 30 October, 2025; originally announced October 2025.

Comments: Data available from Zenodo (https://zenodo.org/records/17343574) or the Gravitational-Wave Open Science Center (https://gwosc.org)

Report number: LIGO-P2500402

Journal ref: Astrophys. J. Letters, 993, L21 (2025)

Cosmological and High Energy Physics implications from gravitational-wave background searches in LIGO-Virgo-KAGRA's O1-O4a runs

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1747 additional authors not shown)

Abstract: We search for gravitational-wave background signals produced by various early Universe processes in the Advanced LIGO O4a dataset, combined with the data from the earlier O1, O2, and O3 (LIGO-Virgo) runs. The absence of detectable signals enables powerful constraints on fundamental physics. We derive gravitational-wave background energy density upper limits from the O1-O4a data to constrain parame… ▽ More We search for gravitational-wave background signals produced by various early Universe processes in the Advanced LIGO O4a dataset, combined with the data from the earlier O1, O2, and O3 (LIGO-Virgo) runs. The absence of detectable signals enables powerful constraints on fundamental physics. We derive gravitational-wave background energy density upper limits from the O1-O4a data to constrain parameters associated with various possible processes in the early Universe: first-order phase transitions, cosmic strings, domain walls, stiff equation of state, axion inflation, second-order scalar perturbations, primordial black hole binaries, and parity violation. In our analyses, the presence of an astrophysical background produced by compact (black hole and neutron star) binary coalescences throughout the Universe is also considered. We address the implications for various cosmological and high energy physics models based on the obtained parameter constraints. We conclude that LIGO-Virgo data already yield significant constraints on numerous early Universe scenarios. △ Less

Submitted 7 November, 2025; v1 submitted 30 October, 2025; originally announced October 2025.

Comments: Main paper: 45 pages, 20 figures

Report number: LIGO-PP2500150

Directional Search for Persistent Gravitational Waves: Results from the First Part of LIGO-Virgo-KAGRA's Fourth Observing Run

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1743 additional authors not shown)

Abstract: The angular distribution of gravitational-wave power from persistent sources may exhibit anisotropies arising from the large-scale structure of the Universe. This motivates directional searches for astrophysical and cosmological gravitational-wave backgrounds, as well as continuous-wave emitters. We present results of such a search using data from the first observing run through the first portion… ▽ More The angular distribution of gravitational-wave power from persistent sources may exhibit anisotropies arising from the large-scale structure of the Universe. This motivates directional searches for astrophysical and cosmological gravitational-wave backgrounds, as well as continuous-wave emitters. We present results of such a search using data from the first observing run through the first portion of the fourth observing run of the LIGO-Virgo-KAGRA Collaborations. We apply gravitational-wave radiometer techniques to generate skymaps and search for both narrowband and broadband persistent gravitational-wave sources. Additionally, we use spherical harmonic decomposition to probe spatially extended sources. No evidence of persistent gravitational-wave signals is found, and we set the most stringent constraints to date on such emissions. For narrowband point sources, our sensitivity estimate to effective strain amplitude lies in the range $(0.03 - 8.4) \times 10^{-24}$ across all sky and frequency range $(20 - 160)$ Hz. For targeted sources -- Scorpius X-1, SN 1987A, the Galactic Center, Terzan 5, and NGC 6397 -- we constrain the strain amplitude with best limits ranging from $\sim 1.1 \times 10^{-25}$ to $6.5 \times 10^{-24}$. For persistent broadband sources, we constrain the gravitational-wave flux $F_{α, \hat{n}}^{95\%, \mathrm{UL}}(25\, \mathrm{Hz}) < (0.008 - 5.5) \times 10^{-8}\, \mathrm{erg\, cm^{-2}\, s^{-1}\, Hz^{-1}}$, depending on the sky direction $\hat{n}$ and spectral index $α=0,\,2/3,\,3$. Finally, for extended sources, we place upper limits on the strain angular power spectrum $C_\ell^{1/2} < (0.63 - 17) \times 10^{-10} \,\mathrm{sr}^{-1}$. △ Less

Submitted 20 October, 2025; originally announced October 2025.

Comments: Main paper: 11 pages and 4 figures; Total with appendices: 39 pages and 12 figures

Report number: LIGO-P250038

Unveiling Central ortho-H2D+ Depletion at Sub-kau Scales in Prestellar Core G205.46-14.56M3: The First Interferometric Evidence and Implications for Deuterium Chemistry

Authors: Sheng-Jun Lin, Sheng-Yuan Liu, Dipen Sahu, Laurent Pagani, Tien-Hao Hsieh, Naomi Hirano, Shih-Ping Lai, Tie Liu, Shih-Ying Hsu, Shanghuo Li, Kee-Tae Kim

Abstract: Prestellar cores represent the initial conditions of star formation, but heavy molecules such as CO are strongly depleted in their cold, dense interiors, limiting the ability to probe core centers. Deuterated molecular ions therefore emerge as key tracers because deuterium fractionation is enhanced at low temperatures. We present the first direct observation of ortho-H2D+ depletion in the prestell… ▽ More Prestellar cores represent the initial conditions of star formation, but heavy molecules such as CO are strongly depleted in their cold, dense interiors, limiting the ability to probe core centers. Deuterated molecular ions therefore emerge as key tracers because deuterium fractionation is enhanced at low temperatures. We present the first direct observation of ortho-H2D+ depletion in the prestellar core G205.46-14.56M3 using ALMA 820um continuum and ortho-H2D+(110-111) data at ~300-au resolution. We confirm the previously reported two substructures, B1 and B2, and identify a central ortho-H2D+ depletion zone toward B1 with ~6$σ$ contrast and an inferred diameter $\lesssim$600au, together with a peak $x$(N2D+)/$x$(N2H+)=$1.03^{+0.07}_{-0.56}$. The observationally inferred profiles of $x$(ortho-H2D+) and $x$(N2D+)/$x$(N2H+) are reproduced by a deuteration-focused chemo-dynamical model; however, the central ortho-H2D+ depletion is only marginally matched within the $2σ$ upper limit, likely suggesting additional deuteration in the depletion zone. From these models we infer a core age of ~0.42Ma, comparable to the free-fall time, suggesting that the substructures formed via rapid, turbulence-dominated fragmentation rather than slow, quasi-static contraction. Our observations also reveal that ortho-H2D+ velocity dispersions are largely subsonic in the core and nearly thermal between B1 and B2, consistent with turbulence dissipating within a few free-fall times. These results highlight the critical role of deuterated ions for both chemical evolution and dynamics in dense cores. △ Less

Submitted 10 December, 2025; v1 submitted 25 September, 2025; originally announced September 2025.

Comments: 22 pages, 8 figures, accepted for publication in ApJ

GW250114: testing Hawking's area law and the Kerr nature of black holes

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1763 additional authors not shown)

Abstract: The gravitational-wave signal GW250114 was observed by the two LIGO detectors with a network matched-filter signal-to-noise ratio of 80. The signal was emitted by the coalescence of two black holes with near-equal masses $m_1 = 33.6^{+1.2}_{-0.8}\,M_\odot$ and $m_2 = 32.2^{+0.8}_{-1.3}\,M_\odot$, and small spins $χ_{1,2} \leq 0.26$ (90% credibility) and negligible eccentricity $e \leq 0.03$. Post-… ▽ More The gravitational-wave signal GW250114 was observed by the two LIGO detectors with a network matched-filter signal-to-noise ratio of 80. The signal was emitted by the coalescence of two black holes with near-equal masses $m_1 = 33.6^{+1.2}_{-0.8}\,M_\odot$ and $m_2 = 32.2^{+0.8}_{-1.3}\,M_\odot$, and small spins $χ_{1,2} \leq 0.26$ (90% credibility) and negligible eccentricity $e \leq 0.03$. Post-merger data excluding the peak region are consistent with the dominant quadrupolar $(\ell = |m| = 2)$ mode of a Kerr black hole and its first overtone. We constrain the modes' frequencies to $\pm 30\%$ of the Kerr spectrum, providing a test of the remnant's Kerr nature. We also examine Hawking's area law, also known as the second law of black hole mechanics, which states that the total area of the black hole event horizons cannot decrease with time. A range of analyses that exclude up to 5 of the strongest merger cycles confirm that the remnant area is larger than the sum of the initial areas to high credibility. △ Less

Submitted 9 September, 2025; originally announced September 2025.

Comments: 6 pages, 5 figures (plus supplement)

Report number: LIGO-P2500421

Directed searches for gravitational waves from ultralight vector boson clouds around merger remnant and galactic black holes during the first part of the fourth LIGO-Virgo-KAGRA observing run

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1747 additional authors not shown)

Abstract: We present the first directed searches for long-transient and continuous gravitational waves from ultralight vector boson clouds around known black holes (BHs). We use LIGO data from the first part of the fourth LIGO-Virgo-KAGRA observing run. The searches target two distinct types of BHs and use two new semicoherent methods: hidden Markov model (HMM) tracking for the remnant BHs of the mergers GW… ▽ More We present the first directed searches for long-transient and continuous gravitational waves from ultralight vector boson clouds around known black holes (BHs). We use LIGO data from the first part of the fourth LIGO-Virgo-KAGRA observing run. The searches target two distinct types of BHs and use two new semicoherent methods: hidden Markov model (HMM) tracking for the remnant BHs of the mergers GW230814_230901 and GW231123_135430 (referred to as GW230814 and GW231123 in this study), and a dedicated method using the Band Sampled Data (BSD) framework for the galactic BH in the Cygnus X-1 binary system. Without finding evidence of a signal from vector bosons in the data, we estimate the mass range that can be constrained. For the HMM searches targeting the remnants from GW231123 and GW230814, we disfavor vector boson masses in the ranges $[0.94, 1.08]$ and $[2.75, 3.28] \times 10^{-13}$ eV, respectively, at 30% confidence, assuming a 1% false alarm probability. Although these searches are only marginally sensitive to signals from merger remnants at relatively large distances, future observations are expected to yield more stringent constraints with high confidence. For the BSD search targeting the BH in Cygnus X-1, we exclude vector boson masses in the range $[0.85, 1.59] \times 10^{-13}$ eV at 95% confidence, assuming an initial BH spin larger than 0.5. △ Less

Submitted 14 September, 2025; v1 submitted 8 September, 2025; originally announced September 2025.

Comments: 33 pages, 4 figures

Report number: LIGO-P2500256

GWTC-4.0: Constraints on the Cosmic Expansion Rate and Modified Gravitational-wave Propagation

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1750 additional authors not shown)

Abstract: We analyze data from 142 of the 218 gravitational-wave (GW) sources in the fourth LIGO-Virgo-KAGRA Collaboration (LVK) Gravitational-Wave Transient Catalog (GWTC-4.0) to estimate the Hubble constant $H_0$ jointly with the population properties of merging compact binaries. We measure the luminosity distance and redshifted masses of GW sources directly; in contrast, we infer GW source redshifts stat… ▽ More We analyze data from 142 of the 218 gravitational-wave (GW) sources in the fourth LIGO-Virgo-KAGRA Collaboration (LVK) Gravitational-Wave Transient Catalog (GWTC-4.0) to estimate the Hubble constant $H_0$ jointly with the population properties of merging compact binaries. We measure the luminosity distance and redshifted masses of GW sources directly; in contrast, we infer GW source redshifts statistically through i) location of features in the compact object mass spectrum and merger rate evolution, and ii) identifying potential host galaxies in the GW localization volume. Probing the relationship between source luminosity distances and redshifts obtained in this way yields constraints on cosmological parameters. We also constrain parameterized deviations from general relativity which affect GW propagation, specifically those modifying the dependence of a GW signal on the source luminosity distance. Assuming our fiducial model for the source-frame mass distribution and using GW candidates detected up to the end of the fourth observing run (O4a), together with the GLADE+ all-sky galaxy catalog, we estimate $H_0 = 76.6^{+13.0}_{-9.5} (76.6^{+25.2}_{-14.0})$ km s$^{-1}$ Mpc$^{-1}$. This value is reported as a median with 68.3% (90%) symmetric credible interval, and includes combination with the $H_0$ measurement from GW170817 and its electromagnetic counterpart. Using a parametrization of modified GW propagation in terms of the magnitude parameter $Ξ_0$, we estimate $Ξ_0 = 1.2^{+0.8}_{-0.4} (1.2^{+2.4}_{-0.5})$, where $Ξ_0 = 1$ recovers the behavior of general relativity. △ Less

Submitted 7 October, 2025; v1 submitted 4 September, 2025; originally announced September 2025.

Comments: As part of the Astrophysical Journal Letters Focus Issue on the Gravitational Wave Transient Catalog

Report number: LIGO-P2400152

The Future of Artificial Intelligence and the Mathematical and Physical Sciences (AI+MPS)

Authors: Andrew Ferguson, Marisa LaFleur, Lars Ruthotto, Jesse Thaler, Yuan-Sen Ting, Pratyush Tiwary, Soledad Villar, E. Paulo Alves, Jeremy Avigad, Simon Billinge, Camille Bilodeau, Keith Brown, Emmanuel Candes, Arghya Chattopadhyay, Bingqing Cheng, Jonathan Clausen, Connor Coley, Andrew Connolly, Fred Daum, Sijia Dong, Chrisy Xiyu Du, Cora Dvorkin, Cristiano Fanelli, Eric B. Ford, Luis Manuel Frutos , et al. (75 additional authors not shown)

Abstract: This community paper developed out of the NSF Workshop on the Future of Artificial Intelligence (AI) and the Mathematical and Physics Sciences (MPS), which was held in March 2025 with the goal of understanding how the MPS domains (Astronomy, Chemistry, Materials Research, Mathematical Sciences, and Physics) can best capitalize on, and contribute to, the future of AI. We present here a summary and… ▽ More This community paper developed out of the NSF Workshop on the Future of Artificial Intelligence (AI) and the Mathematical and Physics Sciences (MPS), which was held in March 2025 with the goal of understanding how the MPS domains (Astronomy, Chemistry, Materials Research, Mathematical Sciences, and Physics) can best capitalize on, and contribute to, the future of AI. We present here a summary and snapshot of the MPS community's perspective, as of Spring/Summer 2025, in a rapidly developing field. The link between AI and MPS is becoming increasingly inextricable; now is a crucial moment to strengthen the link between AI and Science by pursuing a strategy that proactively and thoughtfully leverages the potential of AI for scientific discovery and optimizes opportunities to impact the development of AI by applying concepts from fundamental science. To achieve this, we propose activities and strategic priorities that: (1) enable AI+MPS research in both directions; (2) build up an interdisciplinary community of AI+MPS researchers; and (3) foster education and workforce development in AI for MPS researchers and students. We conclude with a summary of suggested priorities for funding agencies, educational institutions, and individual researchers to help position the MPS community to be a leader in, and take full advantage of, the transformative potential of AI+MPS. △ Less

Submitted 2 October, 2025; v1 submitted 2 September, 2025; originally announced September 2025.

Comments: Community Paper from the NSF Future of AI+MPS Workshop, Cambridge, Massachusetts, March 24-26, 2025, supported by NSF Award Number 2512945; v2: minor clarifications

Upper Limits on the Isotropic Gravitational-Wave Background from the first part of LIGO, Virgo, and KAGRA's fourth Observing Run

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1751 additional authors not shown)

Abstract: We present results from the search for an isotropic gravitational-wave background using Advanced LIGO and Advanced Virgo data from O1 through O4a, the first part of the fourth observing run. This background is the accumulated signal from unresolved sources throughout cosmic history and encodes information about the merger history of compact binaries throughout the Universe, as well as exotic physi… ▽ More We present results from the search for an isotropic gravitational-wave background using Advanced LIGO and Advanced Virgo data from O1 through O4a, the first part of the fourth observing run. This background is the accumulated signal from unresolved sources throughout cosmic history and encodes information about the merger history of compact binaries throughout the Universe, as well as exotic physics and potentially primordial processes from the early cosmos. Our cross-correlation analysis reveals no statistically significant background signal, enabling us to constrain several theoretical scenarios. For compact binary coalescences which approximately follow a 2/3 power-law spectrum, we constrain the fractional energy density to $Ω_{\rm GW}(25{\rm Hz})\leq 2.0\times 10^{-9}$ (95% cred.), a factor of 1.7 improvement over previous results. Scale-invariant backgrounds are constrained to $Ω_{\rm GW}(25{\rm Hz})\leq 2.8\times 10^{-9}$, representing a 2.1x sensitivity gain. We also place new limits on gravity theories predicting non-standard polarization modes and confirm that terrestrial magnetic noise sources remain below detection threshold. Combining these spectral limits with population models for GWTC-4, the latest gravitational-wave event catalog, we find our constraints remain above predicted merger backgrounds but are approaching detectability. The joint analysis combining the background limits shown here with the GWTC-4 catalog enables improved inference of the binary black hole merger rate evolution across cosmic time. Employing GWTC-4 inference results and standard modeling choices, we estimate that the total background arising from compact binary coalescences is $Ω_{\rm CBC}(25{\rm Hz})={0.9^{+1.1}_{-0.5}\times 10^{-9}}$ at 90% confidence, where the largest contribution is due to binary black holes only, $Ω_{\rm BBH}(25{\rm Hz})=0.8^{+1.1}_{-0.5}\times 10^{-9}$. △ Less

Submitted 28 August, 2025; originally announced August 2025.

Comments: 31 pages, 7 figures

Report number: LIGO-P2500349

GWTC-4.0: Updating the Gravitational-Wave Transient Catalog with Observations from the First Part of the Fourth LIGO-Virgo-KAGRA Observing Run

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1748 additional authors not shown)

Abstract: Version 4.0 of the Gravitational-Wave Transient Catalog (GWTC-4.0) adds new candidates detected by the LIGO, Virgo, and KAGRA observatories through the first part of the fourth observing run (O4a: 2023 May 24 15:00:00 to 2024 January 16 16:00:00 UTC) and a preceding engineering run. In this new data, we find 128 new compact binary coalescence candidates that are identified by at least one of our s… ▽ More Version 4.0 of the Gravitational-Wave Transient Catalog (GWTC-4.0) adds new candidates detected by the LIGO, Virgo, and KAGRA observatories through the first part of the fourth observing run (O4a: 2023 May 24 15:00:00 to 2024 January 16 16:00:00 UTC) and a preceding engineering run. In this new data, we find 128 new compact binary coalescence candidates that are identified by at least one of our search algorithms with a probability of astrophysical origin $p_{\rm astro} \geq 0.5$ and that are not vetoed during event validation. We also provide detailed source property measurements for 86 of these that have a false alarm rate $< 1 \rm{yr}^{-1}$. Based on the inferred component masses, these new candidates are consistent with signals from binary black holes and neutron star-black hole binaries (GW230518_125908 and GW230529_181500). Median inferred component masses of binary black holes in the catalog now range from $5.79\,M_\odot$ (GW230627_015337) to $137\,M_\odot$ (GW231123_135430), while GW231123_135430 was probably produced by the most massive binary observed in the catalog. For the first time we have discovered binary black hole signals with network signal-to-noise ratio exceeding 30, GW230814_230901 and GW231226_01520, enabling high-fidelity studies of the waveforms and astrophysical properties of these systems. Combined with the 90 candidates included in GWTC-3.0, the catalog now contains 218 candidates with $p_{\rm astro} \geq 0.5$ and not otherwise vetoed, doubling the size of the catalog and further opening our view of the gravitational-wave Universe. △ Less

Submitted 8 September, 2025; v1 submitted 25 August, 2025; originally announced August 2025.

Comments: As part of the Astrophysical Journal Letters Focus Issue on the Gravitational Wave Transient Catalog

Report number: LIGO-P2400386

Open Data from LIGO, Virgo, and KAGRA through the First Part of the Fourth Observing Run

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1746 additional authors not shown)

Abstract: LIGO, Virgo, and KAGRA form a network of gravitational-wave observatories. Data and analysis results from this network are made publicly available through the Gravitational Wave Open Science Center. This paper describes open data from this network, including the addition of data from the first part of the fourth observing run (O4a) and selected periods from the preceding engineering run, collected… ▽ More LIGO, Virgo, and KAGRA form a network of gravitational-wave observatories. Data and analysis results from this network are made publicly available through the Gravitational Wave Open Science Center. This paper describes open data from this network, including the addition of data from the first part of the fourth observing run (O4a) and selected periods from the preceding engineering run, collected from May 2023 to January 2024. The public data set includes calibrated strain time series for each instrument, data from additional channels used for noise subtraction and detector characterization, and analysis data products from version 4.0 of the Gravitational-Wave Transient Catalog. △ Less

Submitted 4 November, 2025; v1 submitted 25 August, 2025; originally announced August 2025.

Comments: 26 pages. The version updates Table 3, updates the author list, removes one figure, and updates some text for clarity and grammar

Report number: LIGO-P2500167

Decadal upgrade strategy for KAGRA toward post-O5 gravitational-wave astronomy

Authors: KAGRA Collaboration, T. Akutsu, M. Ando, M. Aoumi, A. Araya, Y. Aso, L. Baiotti, R. Bajpai, K. Cannon, A. H. -Y. Chen, D. Chen, H. Chen, A. Chiba, C. Chou, M. Eisenmann, K. Endo, T. Fujimori, S. Garg, D. Haba, S. Haino, R. Harada, H. Hayakawa, K. Hayama, S. Fujii, Y. Himemoto , et al. (129 additional authors not shown)

Abstract: The KAGRA Collaboration has investigated a ten-year upgrade strategy for the KAGRA gravitational wave detector, considering a total of 14 upgrade options that vary in mirror mass, quantum noise reduction techniques, and the quality of cryogenic suspensions. We evaluated the scientific potential of these configurations with a focus on key targets such as parameter estimation of compact binary coale… ▽ More The KAGRA Collaboration has investigated a ten-year upgrade strategy for the KAGRA gravitational wave detector, considering a total of 14 upgrade options that vary in mirror mass, quantum noise reduction techniques, and the quality of cryogenic suspensions. We evaluated the scientific potential of these configurations with a focus on key targets such as parameter estimation of compact binary coalescences, binary neutron star post-merger signals, and continuous gravitational waves. Rather than aiming to improve all science cases uniformly, we prioritized those most sensitive to the detector configuration. Technical feasibility was assessed based on required hardware developments, associated R\&D efforts, cost, and risk. Our study finds that a high-frequency upgrade plan that enhances sensitivity over a broad frequency range above ~200 Hz offers the best balance between scientific return and technical feasibility. Such an upgrade would enable sky localization of binary neutron star mergers at 100 Mpc to better than 0.5 deg$^2$ in a LIGO-Virgo-KAGRA network, and improve the measurement precision of tidal deformability parameter by approximately 10% at median, compared to a network without KAGRA. △ Less

Submitted 5 August, 2025; originally announced August 2025.

Report number: JGW-P2516701

GW231123: a Binary Black Hole Merger with Total Mass 190-265 $M_{\odot}$

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1749 additional authors not shown)

Abstract: On 2023 November 23 the two LIGO observatories both detected GW231123, a gravitational-wave signal consistent with the merger of two black holes with masses $137^{+23}_{-18}\, M_\odot$ and $101^{+22}_{-50}\, M_\odot$ (90\% credible intervals), at luminosity distance 0.7-4.1 Gpc and redshift of $0.40^{+0.27}_{-0.25}$, and a network signal-to-noise ratio of $\sim$20.7. Both black holes exhibit high… ▽ More On 2023 November 23 the two LIGO observatories both detected GW231123, a gravitational-wave signal consistent with the merger of two black holes with masses $137^{+23}_{-18}\, M_\odot$ and $101^{+22}_{-50}\, M_\odot$ (90\% credible intervals), at luminosity distance 0.7-4.1 Gpc and redshift of $0.40^{+0.27}_{-0.25}$, and a network signal-to-noise ratio of $\sim$20.7. Both black holes exhibit high spins, $0.9^{+0.10}_{-0.19}$ and $0.80^{+0.20}_{-0.52}$ respectively. A massive black hole remnant is supported by an independent ringdown analysis. Some properties of GW231123 are subject to large systematic uncertainties, as indicated by differences in inferred parameters between signal models. The primary black hole lies within or above the theorized mass gap where black holes between 60-130 $M_\odot$ should be rare due to pair instability mechanisms, while the secondary spans the gap. The observation of GW231123 therefore suggests the formation of black holes from channels beyond standard stellar collapse, and that intermediate-mass black holes of mass $\sim$200 $M_\odot$ form through gravitational-wave driven mergers. △ Less

Submitted 10 November, 2025; v1 submitted 10 July, 2025; originally announced July 2025.

Comments: 27 pages, 10 figures

Report number: DCC: P2500026-v8

Journal ref: ApJL 993 L25 (2025)

Identification of Noise-Associated Glitches in KAGRA O3GK with Hveto

Authors: T. Akutsu, M. Ando, M. Aoumi, A. Araya, Y. Aso, L. Baiotti, R. Bajpai, K. Cannon, A. H. -Y. Chen, D. Chen, H. Chen, A. Chiba, C. Chou, M. Eisenmann, K. Endo, T. Fujimori, S. Garg, D. Haba, S. Haino, R. Harada, H. Hayakawa, K. Hayama, S. Fujii, Y. Himemoto, N. Hirata , et al. (127 additional authors not shown)

Abstract: Transient noise ("glitches") in gravitational wave detectors can mimic or obscure true signals, significantly reducing detection sensitivity. Identifying and excluding glitch-contaminated data segments is therefore crucial for enhancing the performance of gravitational-wave searches. We perform a noise analysis of the KAGRA data obtained during the O3GK observation. Our analysis is performed with… ▽ More Transient noise ("glitches") in gravitational wave detectors can mimic or obscure true signals, significantly reducing detection sensitivity. Identifying and excluding glitch-contaminated data segments is therefore crucial for enhancing the performance of gravitational-wave searches. We perform a noise analysis of the KAGRA data obtained during the O3GK observation. Our analysis is performed with hierarchical veto (Hveto) which identifies noises based on the statistical time correlation between the main channel and the auxiliary channels. A total of 2,531 noises were vetoed by 28 auxiliary channels with the configuration (i.e., signal-to-noise threshold set to 8) that we chose for Hveto. We identify vetoed events as glitches on the spectrogram via visual examination after plotting them with Q-transformation. By referring to the Gravity Spy project, we categorize 2,354 glitches into six types: blip, helix, scratchy, and scattered light, which correspond to those listed in Gravity Spy, and dot and line, which are not found in the Gravity Spy classification and are thus named based on their spectrogram morphology in KAGRA data. The remaining 177 glitches are determined not to belong to any of these six types. We show how the KAGRA glitch types are related to each subsystem of KAGRA. To investigate the possible correlation between the main channel and the round winner - an auxiliary channel statistically associated with the main channel for vetoing purposes - we visually examine the similarity or difference in the glitch pattern on the spectrogram. We compare the qualitative correlation found through visual examination with coherence, which is known to provide quantitative measurement for the correlation between the main channel and each auxiliary channel. Our comprehensive noise analysis will help improve the data quality of KAGRA by applying it to future KAGRA observation data. △ Less

Submitted 26 June, 2025; originally announced June 2025.

Comments: To appear in Progress of Theoretical and Experimental Physics (PTEP), accepted June 2025

Journal ref: Prog Theor Exp Phys (2025)

ALMASOP. A Rotating Feature Rich in Complex Organic Molecules in a Protostellar Core

Authors: Shih-Ying Hsu, Chin-Fei Lee, Doug Johnstone, Sheng-Yuan Liu, Tie Liu, Leonardo Bronfman, Huei-Ru Vivien Chen, Somnath Dutta, David J. Eden, Naomi Hirano, Mika Juvela, Kee-Tae Kim, Yi-Jehng Kuan, Woojin Kwon, Chang Won Lee, Jeong-Eun Lee, Shanghuo Li, Sheng-Jun Lin, Chun-Fan Liu, Xunchuan Liu, J. A. López-Vázquez, Qiuyi Luo, Mark G. Rawlings, Dipen Sahu, Patricio Sanhueza , et al. (3 additional authors not shown)

Abstract: Interstellar complex organic molecules (COMs) in solar-like young stellar objects (YSOs), particularly within protostellar disks, are of significant interest due to their potential connection to prebiotic chemistry in emerging planetary systems. We report the discovery of a rotating feature enriched in COMs, including CH3OH, CH3CHO, and NH2CHO, in the protostellar core G192.12-11.10. By constructi… ▽ More Interstellar complex organic molecules (COMs) in solar-like young stellar objects (YSOs), particularly within protostellar disks, are of significant interest due to their potential connection to prebiotic chemistry in emerging planetary systems. We report the discovery of a rotating feature enriched in COMs, including CH3OH, CH3CHO, and NH2CHO, in the protostellar core G192.12-11.10. By constructing a YSO model, we find that the COM-rich feature is likely located within or near the boundary of the Keplerian disk. The image synthesis results suggest that additional heating mechanisms leading to a warm ring or a warm inner disk are required to reproduce the observed emission. We discuss possible origins of the COM-rich feature, particularly accretion shocks as a plausible cause for a warm ring. Additionally, molecules such as C18O, H2CO, DCS, H2S, and OCS exhibit distinct behavior compared to CH3OH, indicating a range of physical and chemical conditions within the region. The observed kinematics of H2S and OCS suggest that OCS resides in regions closer to the central protostar than H2S, consistent with previous experimental studies. △ Less

Submitted 18 June, 2025; originally announced June 2025.

Comments: 19 pages, 10+1 figures, accepted by ApJ

ALMASOP. Detection of Turbulence-induced Mass Assembly Shocks in Starless Cores

Authors: Shih-Ying Hsu, Sheng-Yuan Liu, Xunchuan Liu, Pak Shing Li, Tie Liu, Dipen Sahu, Kenichi Tatematsu, Shanghuo Li, Naomi Hirano, Chin-Fei Lee, Sheng-Jun Lin

Abstract: Star formation is a series of mass assembly processes and starless cores, those cold and dense condensations in molecular clouds, play a pivotal role as initial seeds of stars. With only a limited sample of known starless cores, however, the origin and growth of such stellar precursors had not been well characterized previously. Meanwhile, the recent discovery of CH$_3$OH emission, which is genera… ▽ More Star formation is a series of mass assembly processes and starless cores, those cold and dense condensations in molecular clouds, play a pivotal role as initial seeds of stars. With only a limited sample of known starless cores, however, the origin and growth of such stellar precursors had not been well characterized previously. Meanwhile, the recent discovery of CH$_3$OH emission, which is generally associated with desorbed icy mantle in warm regions, particularly at the periphery of starless cores also remains puzzling. We present sensitive ALMA (Band~3) observations (at 3~mm) toward a sample of newly identified starless cores in the Orion Molecular Cloud. The spatially resolved images distinctly indicate that the observed CH$_3$OH and N$_2$H$^+$ emission associated with these cores are morphologically anti-correlated and kinematically offset from each other. We postulate that the CH$_3$OH emission highlights the desorption of icy mantle by shocks resulting from gas piling onto dense cores in the filaments traced by N$_2$H$^+$. Our magnetohydrodynamic (MHD) simulations of star formation in turbulent clouds combined with radiative transfer calculations and imaging simulations successfully reproduced the observed signatures and reaffirmed the above scenario at work. Our result serves as an intriguing and exemplary illustration, a snapshot in time, of the dynamic star-forming processes in turbulent clouds. The results offer compelling insights into the mechanisms governing the growth of starless cores and the presence of gas-phase complex organic molecules associated with these cores. △ Less

Submitted 16 April, 2025; originally announced April 2025.

Comments: 12 pages, 4+1 figures, accepted by ApJL

Building Machine Learning Challenges for Anomaly Detection in Science

Authors: Elizabeth G. Campolongo, Yuan-Tang Chou, Ekaterina Govorkova, Wahid Bhimji, Wei-Lun Chao, Chris Harris, Shih-Chieh Hsu, Hilmar Lapp, Mark S. Neubauer, Josephine Namayanja, Aneesh Subramanian, Philip Harris, Advaith Anand, David E. Carlyn, Subhankar Ghosh, Christopher Lawrence, Eric Moreno, Ryan Raikman, Jiaman Wu, Ziheng Zhang, Bayu Adhi, Mohammad Ahmadi Gharehtoragh, Saúl Alonso Monsalve, Marta Babicz, Furqan Baig , et al. (125 additional authors not shown)

Abstract: Scientific discoveries are often made by finding a pattern or object that was not predicted by the known rules of science. Oftentimes, these anomalous events or objects that do not conform to the norms are an indication that the rules of science governing the data are incomplete, and something new needs to be present to explain these unexpected outliers. The challenge of finding anomalies can be c… ▽ More Scientific discoveries are often made by finding a pattern or object that was not predicted by the known rules of science. Oftentimes, these anomalous events or objects that do not conform to the norms are an indication that the rules of science governing the data are incomplete, and something new needs to be present to explain these unexpected outliers. The challenge of finding anomalies can be confounding since it requires codifying a complete knowledge of the known scientific behaviors and then projecting these known behaviors on the data to look for deviations. When utilizing machine learning, this presents a particular challenge since we require that the model not only understands scientific data perfectly but also recognizes when the data is inconsistent and out of the scope of its trained behavior. In this paper, we present three datasets aimed at developing machine learning-based anomaly detection for disparate scientific domains covering astrophysics, genomics, and polar science. We present the different datasets along with a scheme to make machine learning challenges around the three datasets findable, accessible, interoperable, and reusable (FAIR). Furthermore, we present an approach that generalizes to future machine learning challenges, enabling the possibility of large, more compute-intensive challenges that can ultimately lead to scientific discovery. △ Less

Submitted 29 March, 2025; v1 submitted 3 March, 2025; originally announced March 2025.

Comments: 17 pages 6 figures to be submitted to Nature Communications

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Nested Morphological and Kinematic Structures of Outflows Revealed in SiO and CO Emission

Authors: Chun-Fan Liu, Hsien Shang, Doug Johnstone, Tsung-Han Ai, Tsz Ming Lee, Ruben Krasnopolsky, Naomi Hirano, Somnath Dutta, Shih-Ying Hsu, Jesús Alejandro López-Vázquez, Sheng-Yuan Liu, Tie Liu, Ken'ichi Tatematsu, Qizhou Zhang, Mark G. Rawlings, David Eden, Zhiyuan Ren, Patricio Sanhueza, Woojin Kwon, Chang Won Lee, Yi-Jehng Kuan, Somdeb Bandopadhyay, Miikka S. Väisälä, Chin-Fei Lee, Indrani Das

Abstract: The Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP) reveals complex nested morphological and kinematic features of molecular outflows through the CO (J = 2 - 1) and SiO (J = 5 - 4) emission. We characterize the jet and outflow kinematics of the ALMASOP sample in four representative sources (HOPS 10, 315, 358, and G203.21-11.20W2) through channel m… ▽ More The Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP) reveals complex nested morphological and kinematic features of molecular outflows through the CO (J = 2 - 1) and SiO (J = 5 - 4) emission. We characterize the jet and outflow kinematics of the ALMASOP sample in four representative sources (HOPS 10, 315, 358, and G203.21-11.20W2) through channel maps and position-velocity diagrams (PVDs) parallel and transverse to the outflow axes. The combined CO and SiO emission exhibits the coexistence of the conventional extremely-high-velocity (EHV) jets and shell-like low-velocity (LV) cavity walls and new features. More complex, nested bubble-like and filamentary structures in the images and channel maps, triangle-shaped regions near the base of the parallel PVDs, and regions composed of rhombus/oval shapes in the transverse PVDs, are also evident. Such features find natural explanations within the bubble structure of the unified model of jet, wind, and ambient medium. The reverse shock cavity is revealed on the PVD base regions, and other features naturally arise within the dynamic postshock region of magnetic interaction. The finer nested shells observed within the compressed wind region reveal previously unnoticed shocked emission between the jet and the conventional large cavity walls. These pseudopulse-produced filamentary features connect to the jet-like knotty blobs, creating an impression of episodicity in mass ejection. SiO emission is enhanced downstream of the reverse shock boundary, with jet-like excitation conditions. Combined, these observed features reveal the extended structures induced by the magnetic interplay between a jet-bearing magnetized wide-angle wind and its ambient magnetized surrounding medium. △ Less

Submitted 13 November, 2024; originally announced November 2024.

Comments: 27 pages, 11 figures, accepted by ApJ

ALMASOP. The Localized and Chemically rich Features near the Bases of the Protostellar Jet in HOPS 87

Authors: Shih-Ying Hsu, Chin-Fei Lee, Sheng-Yuan Liu, Doug Johnstone, Tie Liu, Satoko Takahashi, Leonardo Bronfman, Huei-Ru Vivien Chen, Somnath Dutta, David J. Eden, Neal J. Evans II, Naomi Hirano, Mika Juvela, Yi-Jehng Kuan, Woojin Kwon, Chang Won Lee, Jeong-Eun Lee, Shanghuo Li, Chun-Fan Liu, Xunchuan Liu, Qiuyi Luo, Sheng-Li Qin, Dipen Sahu, Patricio Sanhueza, Hsien Shang , et al. (2 additional authors not shown)

Abstract: HOPS 87 is a Class 0 protostellar core known to harbor an extremely young bipolar outflow and a hot corino. We report the discovery of localized, chemically rich regions near the bases of the two-lobe bipolar molecular outflow in HOPS 87 containing molecules such as H$_2$CO, $^{13}$CS, H$_2$S, OCS, and CH$_3$OH, the simplest complex organic molecule (COM). The locations and kinematics suggest that… ▽ More HOPS 87 is a Class 0 protostellar core known to harbor an extremely young bipolar outflow and a hot corino. We report the discovery of localized, chemically rich regions near the bases of the two-lobe bipolar molecular outflow in HOPS 87 containing molecules such as H$_2$CO, $^{13}$CS, H$_2$S, OCS, and CH$_3$OH, the simplest complex organic molecule (COM). The locations and kinematics suggest that these localized features are due to jet-driven shocks rather than being part of the hot corino region encasing the protostar. The COM compositions of the molecular gas in these jet-localized regions are relatively simpler than those in the hot corino zone. We speculate that this simplicity is due to either the liberation of ice with a less complex chemical history or the effects of shock chemistry. Our study highlights the dynamic interplay between the protostellar bipolar outflow, disk, inner core environment, and the surrounding medium, contributing to our understanding of molecular complexity in solar-like young stellar objects. △ Less

Submitted 22 September, 2024; originally announced September 2024.

Comments: 16 pages, 6+2 figures, accepted by ApJ

Swift-BAT GUANO follow-up of gravitational-wave triggers in the third LIGO-Virgo-KAGRA observing run

Authors: Gayathri Raman, Samuele Ronchini, James Delaunay, Aaron Tohuvavohu, Jamie A. Kennea, Tyler Parsotan, Elena Ambrosi, Maria Grazia Bernardini, Sergio Campana, Giancarlo Cusumano, Antonino D'Ai, Paolo D'Avanzo, Valerio D'Elia, Massimiliano De Pasquale, Simone Dichiara, Phil Evans, Dieter Hartmann, Paul Kuin, Andrea Melandri, Paul O'Brien, Julian P. Osborne, Kim Page, David M. Palmer, Boris Sbarufatti, Gianpiero Tagliaferri , et al. (1797 additional authors not shown)

Abstract: We present results from a search for X-ray/gamma-ray counterparts of gravitational-wave (GW) candidates from the third observing run (O3) of the LIGO-Virgo-KAGRA (LVK) network using the Swift Burst Alert Telescope (Swift-BAT). The search includes 636 GW candidates received in low latency, 86 of which have been confirmed by the offline analysis and included in the third cumulative Gravitational-Wav… ▽ More We present results from a search for X-ray/gamma-ray counterparts of gravitational-wave (GW) candidates from the third observing run (O3) of the LIGO-Virgo-KAGRA (LVK) network using the Swift Burst Alert Telescope (Swift-BAT). The search includes 636 GW candidates received in low latency, 86 of which have been confirmed by the offline analysis and included in the third cumulative Gravitational-Wave Transient Catalogs (GWTC-3). Targeted searches were carried out on the entire GW sample using the maximum--likelihood NITRATES pipeline on the BAT data made available via the GUANO infrastructure. We do not detect any significant electromagnetic emission that is temporally and spatially coincident with any of the GW candidates. We report flux upper limits in the 15-350 keV band as a function of sky position for all the catalog candidates. For GW candidates where the Swift-BAT false alarm rate is less than 10$^{-3}$ Hz, we compute the GW--BAT joint false alarm rate. Finally, the derived Swift-BAT upper limits are used to infer constraints on the putative electromagnetic emission associated with binary black hole mergers. △ Less

Submitted 27 March, 2025; v1 submitted 13 July, 2024; originally announced July 2024.

Comments: Update to version accepted for publication in ApJ. 50 pages, 10 figures, 4 tables

Journal ref: ApJ, Volume 980, 2025, 207

Ultralight vector dark matter search using data from the KAGRA O3GK run

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, R. Abbott, H. Abe, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, N. Adhikari, R. X. Adhikari, V. K. Adkins, V. B. Adya, C. Affeldt, D. Agarwal, M. Agathos, O. D. Aguiar, I. Aguilar, L. Aiello, A. Ain, P. Ajith, T. Akutsu, S. Albanesi , et al. (1778 additional authors not shown)

Abstract: Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we prese… ▽ More Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for $U(1)_{B-L}$ gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the $U(1)_{B-L}$ gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM. △ Less

Submitted 5 March, 2024; originally announced March 2024.

Comments: 20 pages, 5 figures

Report number: LIGO-P2300250

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Discovery of an extremely dense and compact object embedded in the prestellar core G208.68-19.92-N2

Authors: Naomi Hirano, Dipen Sahu, Sheng-Yaun Liu, Tie Liu, Ken'ichi Tatematsu, Somnath Dutta, Shanghuo Li, Chin-Fei Lee, Pak Shing Li, Shih-Ying Hsu, Sheng-Jun Lin, Doug Johnstone, Leonardo Bronfman, Huei-Ru Vivien Chen, David J. Eden, Yi-Jehng Kuan, Woojin Kwon, Chang Won Lee, Hong-Li Liu, Mark G. Rawlings, Isabelle Ristorcelli, Alessio Traficante

Abstract: The internal structure of the prestellar core G208.68-19.02-N2 (G208-N2) in the Orion Molecular Cloud 3 (OMC-3) region has been studied with the Atacama Large Millimeter/submillimeter Array (ALMA). The dust continuum emission revealed a filamentary structure with a length of $\sim$5000 au and an average H$_2$ volume density of $\sim$6 $\times$ 10$^7$ cm$^{-3}$. At the tip of this filamentary struc… ▽ More The internal structure of the prestellar core G208.68-19.02-N2 (G208-N2) in the Orion Molecular Cloud 3 (OMC-3) region has been studied with the Atacama Large Millimeter/submillimeter Array (ALMA). The dust continuum emission revealed a filamentary structure with a length of $\sim$5000 au and an average H$_2$ volume density of $\sim$6 $\times$ 10$^7$ cm$^{-3}$. At the tip of this filamentary structure, there is a compact object, which we call a ``nucleus", with a radius of $\sim$150--200 au and a mass of $\sim$0.1 M$_{\odot}$. The nucleus has a central density of $\sim$2 $\times$ 10$^9$ cm$^{-3}$ with a radial density profile of $r^{-1.87{\pm}0.11}$. The density scaling of the nucleus is $\sim$3.7 times higher than that of the singular isothermal sphere. This as well as the very low virial parameter of 0.39 suggest that the gravity is dominant over the pressure everywhere in the nucleus. However, there is no sign of CO outflow localized to this nucleus. The filamentary structure is traced by the N$_2$D$^+$ 3--2 emission, but not by the C$^{18}$O 2--1 emission, implying the significant CO depletion due to high density and cold temperature. Toward the nucleus, the N$_2$D$^+$ also shows the signature of depletion. This could imply either the depletion of the parent molecule, N$_2$, or the presence of the embedded very-low luminosity central source that could sublimate the CO in the very small area. The nucleus in G208-N2 is considered to be a prestellar core on the verge of first hydrostatic core (FHSC) formation or a candidate for the FHSC. △ Less

Submitted 9 November, 2023; originally announced November 2023.

Comments: 27 pages, 16 figures

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): The Warm-Envelope Origin of Hot Corinos

Authors: Shih-Ying Hsu, Sheng-Yuan Liu, Doug Johnstone, Tie Liu, Leonardo Bronfman, Huei-Ru Vivien Chen, Somnath Dutta, David J. Eden, Neal J. Evans II, Naomi Hirano, Mika Juvela, Yi-Jehng Kuan, Woojin Kwon, Chin-Fei Lee, Chang Won Lee, Jeong-Eun Lee, Shanghuo Li, Chun-Fan Liu, Xunchuan Liu, Qiuyi Luo, Sheng-Li Qin, Mark G. Rawlings, Dipen Sahu, Patricio Sanhueza, Hsien Shang , et al. (2 additional authors not shown)

Abstract: Hot corinos are of great interest due to their richness in interstellar complex organic molecules (COMs) and the consequent potential prebiotic connection to solar-like planetary systems. Recent surveys have reported an increasing number of hot corino detections in Class 0/I protostars; however, the relationships between their physical properties and the hot-corino signatures remain elusive. In th… ▽ More Hot corinos are of great interest due to their richness in interstellar complex organic molecules (COMs) and the consequent potential prebiotic connection to solar-like planetary systems. Recent surveys have reported an increasing number of hot corino detections in Class 0/I protostars; however, the relationships between their physical properties and the hot-corino signatures remain elusive. In this study, our objective is to establish a general picture of the detectability of the hot corinos by identifying the origin of the hot-corino signatures in the sample of young stellar objects (YSOs) obtained from the Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP) project. We apply spectral energy distribution (SED) modeling to our sample and identify the physical parameters of the modeled YSOs directly, linking the detection of hot-corino signatures to the envelope properties of the YSOs. Imaging simulations of the methanol emission further support this scenario. We, therefore, posit that the observed COM emission originates from the warm inner envelopes of the sample YSOs, based on both the warm region size and the envelope density profile. The former is governed by the source luminosity and is additionally affected by the disk and cavity properties, while the latter is related to the evolutionary stages. This scenario provides a framework for detecting hot-corino signatures toward luminous Class 0 YSOs, with fewer detections observed toward similarly luminous Class I sources. △ Less

Submitted 11 August, 2023; v1 submitted 10 August, 2023; originally announced August 2023.

Comments: 28 pages, 11 figures

Search for Eccentric Black Hole Coalescences during the Third Observing Run of LIGO and Virgo

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, R. Abbott, H. Abe, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, N. Adhikari, R. X. Adhikari, V. K. Adkins, V. B. Adya, C. Affeldt, D. Agarwal, M. Agathos, O. D. Aguiar, I. Aguilar, L. Aiello, A. Ain, P. Ajith, T. Akutsu, S. Albanesi, R. A. Alfaidi , et al. (1750 additional authors not shown)

Abstract: Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effect… ▽ More Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass $M>70$ $M_\odot$) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities $0 < e \leq 0.3$ at $0.33$ Gpc$^{-3}$ yr$^{-1}$ at 90\% confidence level. △ Less

Submitted 7 August, 2023; originally announced August 2023.

Comments: 24 pages, 5 figures

Report number: LIGO-P2300080

Episodic Accretion in Protostars -- An ALMA Survey of Molecular Jets in the Orion Molecular Cloud

Authors: Somnath Dutta, Chin-Fei Lee, Doug Johnstone, Jeong-Eun Lee, Naomi Hirano, James Di Francesco, Anthony Moraghan, Tie Liu, Dipen Sahu, Sheng-Yuan Liu, Kenichi Tatematsu, Chang Won Lee, Shanghuo Li, David Eden, Mika Juvela, Leonardo Bronfman, Shih-Ying Hsu, Kee-Tae Kim, Woojin Kwon, Patricio Sanhueza, Jesus Alejandro Lopez-Vazquez, Qiuyi Luo, Hee-Weon Yi

Abstract: Protostellar outflows and jets are almost ubiquitous characteristics during the mass accretion phase, and encode the history of stellar accretion, complex-organic molecule (COM) formation, and planet formation. Episodic jets are likely connected to episodic accretion through the disk. Despite the importance, there is a lack of studies of a statistically significant sample of protostars via high-se… ▽ More Protostellar outflows and jets are almost ubiquitous characteristics during the mass accretion phase, and encode the history of stellar accretion, complex-organic molecule (COM) formation, and planet formation. Episodic jets are likely connected to episodic accretion through the disk. Despite the importance, there is a lack of studies of a statistically significant sample of protostars via high-sensitivity and high-resolution observations. To explore episodic accretion mechanisms and the chronologies of episodic events, we investigated 42 fields containing protostars with ALMA observations of CO, SiO, and 1.3\,mm continuum emission. We detected SiO emission in 21 fields, where 19 sources are driving confirmed molecular jets with high abundances of SiO. Jet velocities, mass-loss rates, mass-accretion rates, and periods of accretion events are found to be dependent on the driving forces of the jet (e.g., bolometric luminosity, envelope mass). Next, velocities and mass-loss rates are positively correlated with the surrounding envelope mass, suggesting that the presence of high mass around protostars increases the ejection-accretion activity. We determine mean periods of ejection events of 20$-$175 years for our sample, which could be associated with perturbation zones of $\sim$ 2$-$25\,au extent around the protostars. Also, mean ejection periods are anti-correlated with the envelope mass, where high-accretion rates may trigger more frequent ejection events. The observed periods of outburst/ejection are much shorter than the freeze-out time scale of the simplest COMs like CH$_3$OH, suggesting that episodic events largely maintain the ice-gas balance inside and around the snowline. △ Less

Submitted 27 June, 2023; originally announced June 2023.

Comments: Submitted to Journal; 27 pages, 15 Figures and additional Appendix material

Applications of Deep Learning to physics workflows

Authors: Manan Agarwal, Jay Alameda, Jeroen Audenaert, Will Benoit, Damon Beveridge, Meghna Bhattacharya, Chayan Chatterjee, Deep Chatterjee, Andy Chen, Muhammed Saleem Cholayil, Chia-Jui Chou, Sunil Choudhary, Michael Coughlin, Maximilian Dax, Aman Desai, Andrea Di Luca, Javier Mauricio Duarte, Steven Farrell, Yongbin Feng, Pooyan Goodarzi, Ekaterina Govorkova, Matthew Graham, Jonathan Guiang, Alec Gunny, Weichangfeng Guo , et al. (43 additional authors not shown)

Abstract: Modern large-scale physics experiments create datasets with sizes and streaming rates that can exceed those from industry leaders such as Google Cloud and Netflix. Fully processing these datasets requires both sufficient compute power and efficient workflows. Recent advances in Machine Learning (ML) and Artificial Intelligence (AI) can either improve or replace existing domain-specific algorithms… ▽ More Modern large-scale physics experiments create datasets with sizes and streaming rates that can exceed those from industry leaders such as Google Cloud and Netflix. Fully processing these datasets requires both sufficient compute power and efficient workflows. Recent advances in Machine Learning (ML) and Artificial Intelligence (AI) can either improve or replace existing domain-specific algorithms to increase workflow efficiency. Not only can these algorithms improve the physics performance of current algorithms, but they can often be executed more quickly, especially when run on coprocessors such as GPUs or FPGAs. In the winter of 2023, MIT hosted the Accelerating Physics with ML at MIT workshop, which brought together researchers from gravitational-wave physics, multi-messenger astrophysics, and particle physics to discuss and share current efforts to integrate ML tools into their workflows. The following white paper highlights examples of algorithms and computing frameworks discussed during this workshop and summarizes the expected computing needs for the immediate future of the involved fields. △ Less

Submitted 13 June, 2023; originally announced June 2023.

Comments: Whitepaper resulting from Accelerating Physics with ML@MIT workshop in Jan/Feb 2023

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): A forming quadruple system with continuum `ribbons' and intricate outflows

Authors: Qiu-yi Luo, Tie Liu, Aaron T. Lee, Stella S. R. Offner, James di Francesco, Doug Johnstone, Mika Juvela, Paul F. Goldsmith, Sheng-Li Qin, Xiaofeng Mai, Xun-chuan Liu, Patricio Sanhueza, Feng-Wei Xu, Ken'ichi Tatematsu, Somnath Dutta, Huei-Ru Vivien Chen, Shanghuo Li, Aiyuan Yang, Sheng-Yuan Liu, Chin-Fei Lee, Naomi Hirano, Chang Won Lee, Dipen Sahu, Hsien Shang, Shih-Ying Hsu , et al. (9 additional authors not shown)

Abstract: One of the most poorly understood aspects of low-mass star formation is how multiple-star systems are formed. Here we present the results of Atacama Large Millimeter/submillimeter Array (ALMA) Band-6 observations towards a forming quadruple protostellar system, G206.93-16.61E2, in the Orion B molecular cloud. ALMA 1.3 mm continuum emission reveals four compact objects, of which two are Class I you… ▽ More One of the most poorly understood aspects of low-mass star formation is how multiple-star systems are formed. Here we present the results of Atacama Large Millimeter/submillimeter Array (ALMA) Band-6 observations towards a forming quadruple protostellar system, G206.93-16.61E2, in the Orion B molecular cloud. ALMA 1.3 mm continuum emission reveals four compact objects, of which two are Class I young stellar objects (YSOs), and the other two are likely in prestellar phase. The 1.3 mm continuum emission also shows three asymmetric ribbon-like structures that are connected to the four objects, with lengths ranging from $\sim$500 au to $\sim$2200 au. By comparing our data with magneto-hydrodynamic (MHD) simulations, we suggest that these ribbons trace accretion flows and also function as gas bridges connecting the member protostars. Additionally, ALMA CO J=2-1 line emission reveals a complicated molecular outflow associated with G206.93-16.61E2 with arc-like structures suggestive of an outflow cavity viewed pole-on. △ Less

Submitted 13 June, 2023; originally announced June 2023.

Comments: The paper was accepted by APJL

Density Structure of Centrally Concentrated Prestellar Cores from Multi-scale Observations

Authors: Dipen Sahu, Sheng-Yuan Liu, Doug Johnstone, Tie Liu, Neal J. Evans II, Naomi Hirano, Kenichi Tatematsu, James Di Francesco, Chin-Fei Lee, Kee-Tae Kim, Somnath Dutta, Shih-Ying Hsu, Shanghuo Li, Qiu-Yi Luo, Patricio Sanhueza, Hsien Shang, Alessio Traficante, Mika Juvela, Chang Won Lee, David J. Eden, Paul F. Goldsmith, Leonardo Bronfman, Woojin Kwon, Jeong-Eun Lee, Yi-Jehng Kuan , et al. (1 additional authors not shown)

Abstract: Starless cores represent the initial stage of evolution toward (proto)star formation, and a subset of them, known as prestellar cores, with high density (~ 10^6 cm^-3 or higher) and being centrally concentrated are expected to be embryos of (proto)stars. Determining the density profile of prestellar cores, therefore provides an important opportunity to gauge the initial conditions of star formatio… ▽ More Starless cores represent the initial stage of evolution toward (proto)star formation, and a subset of them, known as prestellar cores, with high density (~ 10^6 cm^-3 or higher) and being centrally concentrated are expected to be embryos of (proto)stars. Determining the density profile of prestellar cores, therefore provides an important opportunity to gauge the initial conditions of star formation. In this work, we perform rigorous modeling to estimate the density profiles of three nearly spherical prestellar cores among a sample of five highly dense cores detected by our recent observations. We employed multi-scale observational data of the (sub)millimeter dust continuum emission including those obtained by SCUBA-2 on the JCMT with a resolution of ~5600 au and by multiple ALMA observations with a resolution as high as ~480 au. We are able to consistently reproduce the observed multi-scale dust continuum images of the cores with a simple prescribed density profile, which bears an inner region of flat density and a r^-2 profile toward the outer region. By utilizing the peak density and the size of the inner flat region as a proxy for the dynamical stage of the cores, we find that the three modeled cores are most likely unstable and prone to collapse. The sizes of the inner flat regions, as compact as ~500 au, signify them being the highly evolved prestellar cores rarely found to date. △ Less

Submitted 14 February, 2023; originally announced February 2023.

Comments: Accepted for publication in ApJ

TAROGE-M: Radio Antenna Array on Antarctic High Mountain for Detecting Near-Horizontal Ultra-High Energy Air Showers

Authors: TAROGE Collaboration, Shih-Hao Wang, Jiwoo Nam, Pisin Chen, Yaocheng Chen, Taejin Choi, Young-bae Ham, Shih-Ying Hsu, Jian-Jung Huang, Ming-Huey A. Huang, Geonhwa Jee, Jongil Jung, Jieun Kim, Chung-Yun Kuo, Hyuck-Jin Kwon, Changsup Lee, Chung-Hei Leung, Tsung-Che Liu, Yu-Shao J. Shiao, Bok-Kyun Shin, Min-Zu Wang, Yu-Hsin Wang, ARIANNA Collaboration, :, Astrid Anker , et al. (23 additional authors not shown)

Abstract: TAROGE-M is a self-triggered radio antenna array atop the 2700 m high Mt. Melbourne in Antarctica, designed to detect impulsive geomagnetic emission from extensive air showers induced by ultra-high energy (UHE) particles beyond 0.1 EeV, including cosmic rays (CRs), Earth-skimming tau neutrinos, and particularly, the "ANITA anomalous events" (AAEs) from near and below the horizon, which origin rema… ▽ More TAROGE-M is a self-triggered radio antenna array atop the 2700 m high Mt. Melbourne in Antarctica, designed to detect impulsive geomagnetic emission from extensive air showers induced by ultra-high energy (UHE) particles beyond 0.1 EeV, including cosmic rays (CRs), Earth-skimming tau neutrinos, and particularly, the "ANITA anomalous events" (AAEs) from near and below the horizon, which origin remains uncertain and requires more experimental inputs for clarification. The detection concept of TAROGE-M takes advantage of a high altitude with synoptic view toward the horizon as an efficient signal collector, and the radio quietness as well as strong and near vertical geomagnetic field in Antarctica. This approach has a low energy threshold, high duty cycle, and is easy to extend for quickly enlarging statistics. Here we report experimental results from the first TAROGE-M station deployed in 2020, corresponding to $25.3$-days of livetime. The station consists of six receiving antennas operating at 180-450 MHz, and can reconstruct source directions with $\sim0.3^\circ$ angular resolution. To demonstrate its ability to detect UHE air showers, a search for CR signals in the data was conducted, resulting in seven identified events. These events have a mean reconstructed energy of $0.95_{-0.31}^{+0.46}$ EeV and zenith angles between $25^\circ-82^\circ$, with both distributions agreeing with simulations. The estimated CR flux is also consistent with results of other experiments. The TAROGE-M sensitivity to AAEs is approximated by the tau neutrino exposure with simulations, suggesting comparable sensitivity as ANITA's at $~1$ EeV energy with a few station-years of operation. These first results verified the station design and performance in a polar and high-altitude environment, and are promising for further discovery of tau neutrinos and AAEs after an extension in the near future. △ Less

Submitted 26 September, 2022; v1 submitted 21 July, 2022; originally announced July 2022.

Comments: 41 pages, 23 figures, submitted to JCAP; minor corrections in references; minor modifications in simulation description in section 5 & 6 for clarity

Journal ref: JCAP11(2022)022

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Deriving Inclination Angle and Velocity of the Protostellar Jets from their SiO Knots

Authors: Kai-Syun Jhan, Chin-Fei Lee, Doug Johnstone, Tie Liu, Sheng-Yuan Liu, Naomi Hirano, Kenichi Tatematsu, Somnath Dutta, Anthony Moraghan, Hsien Shang, Jeong-Eun Lee, Shanghuo Li, Chun-Fan Liu, Shih-Ying Hsu, Woojin Kwon, Dipen Sahu, Xun-Chuan Liu, Kee-Tae Kim, Qiuyi Luo, Sheng-Li Qin, Patricio Sanhueza, Leonardo Bronfman, Zhang Qizhou, David Eden, Alessio Traficante , et al. (1 additional authors not shown)

Abstract: We have selected six sources (G209.55-19.68S2, G205.46-14.56S1$_{-}$A, G203.21-11.20W2, G191.90-11.21S, G205.46-14.56S3, and G206.93-16.61W2) from the Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP), in which these sources have been mapped in the CO (J=2-1), SiO (J=5-4), and C$^{18}$O (J=2-1) lines. These sources have high-velocity SiO jets surrou… ▽ More We have selected six sources (G209.55-19.68S2, G205.46-14.56S1$_{-}$A, G203.21-11.20W2, G191.90-11.21S, G205.46-14.56S3, and G206.93-16.61W2) from the Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP), in which these sources have been mapped in the CO (J=2-1), SiO (J=5-4), and C$^{18}$O (J=2-1) lines. These sources have high-velocity SiO jets surrounded by low-velocity CO outflows. The SiO jets consist of a chain of knots. These knots have been thought to be produced by semi-periodical variations in jet velocity. Therefore, we adopt a shock-forming model, which uses such variations to estimate the inclination angle and velocity of the jets. We also derive the inclination angle of the CO outflows using the wide-angle wind-driven shell model, and find it to be broadly consistent with that of the associated SiO jets. In addition, we apply this shock-forming model to another three protostellar sources with SiO jets in the literature -- HH 211, HH 212, and L1448C(N) -- and find that their inclination angle and jet velocity are consistent with those previously estimated from proper motion and radial velocity studies. △ Less

Submitted 27 April, 2022; originally announced April 2022.

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Evidence for a Molecular Jet Launched at an Unprecedented Early Phase of Protostellar evolution

Authors: Somnath Dutta, Chin-Fei Lee, Naomi Hirano, Tie Liu, Doug Johnstone, Sheng-Yuan Liu, Kenichi Tatematsu, Paul F. Goldsmith, Dipen Sahu, Neal J. Evans, Patricio Sanhueza, Woojin Kwon, Sheng-Li Qin, Manash Ranjan Samal, Qizhou Zhang, Kee-Tae Kim, Hsien Shang, Chang Won Lee, Anthony Moraghan, Kai-Syun Jhan, Shanghuo Li, Jeong-Eun Lee, Alessio Traficante, Mika Juvela, Leonardo Bronfman , et al. (9 additional authors not shown)

Abstract: Protostellar outflows and jets play a vital role in star formation as they carry away excess angular momentum from the inner disk surface, allowing the material to be transferred toward the central protostar. Theoretically, low velocity and poorly collimated outflows appear from the beginning of the collapse, at the first hydrostatic core (FHSC) stage. With growing protostellar core mass, high-den… ▽ More Protostellar outflows and jets play a vital role in star formation as they carry away excess angular momentum from the inner disk surface, allowing the material to be transferred toward the central protostar. Theoretically, low velocity and poorly collimated outflows appear from the beginning of the collapse, at the first hydrostatic core (FHSC) stage. With growing protostellar core mass, high-density jets are launched which entrain an outflow from the infalling envelope. Until now, molecular jets have been observed at high velocity ($\gtrsim$ 100 km/s) in early Class\,0 protostars. We, for the first time, detect a dense molecular jet in SiO emission with small-velocity ($\sim$ 4.2 km\,s$^{-1}$, deprojected $\sim$ 24 km\,s$^{-1}$) from source G208.89-20.04Walma (hereafter, G208Walma) using ALMA Band\,6 observations. This object has some characteristics of FHSCs, such as a small outflow/jet velocity, extended 1.3\,mm continuum emission, and N$_2$D$^+$ line emission. Additional characteristics, however, are typical of early protostars: collimated outflow and SiO jet. The full extent of the outflow corresponds to a dynamical time scale of $\sim$ 930$^{+200}_{-100}$ years. The spectral energy distribution also suggests a very young source having an upper limit of T$_{bol}$ $\sim$ 31 K and L$_{bol}$ $\sim$ 0.8 L$_\sun$. We conclude that G208Walma is likely in the transition phase from FHSC to protostar, and the molecular jet has been launched within a few hundred years of initial collapse. Therefore, G208Walma may be the earliest object discovered in the protostellar phase with a molecular jet. △ Less

Submitted 13 April, 2022; originally announced April 2022.

Comments: 16 pages, 7 figures. accepted for publication in ApJ

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): How do dense core properties affect the multiplicity of protostars?

Authors: Qiuyi Luo, Tie Liu, Kenichi Tatematsu, ShengYuan Liu, Pak Shing Li, James di Francesco, Doug Johnstone, Paul F. Goldsmith, Somnath Dutta, Naomi Hirano, ChinFei Lee, Di Li, KeeTae Kim, Chang Won Lee, JeongEun Lee, Xunchuan Liu, Mika Juvela, Jinhua He, ShengLi Qin, HongLi Liu, David Eden, Woojin Kwon, Dipen Sahu, Shanghuo Li, FengWei Xu , et al. (12 additional authors not shown)

Abstract: During the transition phase from a prestellar to a protostellar cloud core, one or several protostars can form within a single gas core. The detailed physical processes of this transition, however, still remain unclear. We present 1.3 mm dust continuum and molecular line observations with the Atacama Large Millimeter/submillimeter Array (ALMA) toward 43 protostellar cores in the Orion Molecular Cl… ▽ More During the transition phase from a prestellar to a protostellar cloud core, one or several protostars can form within a single gas core. The detailed physical processes of this transition, however, still remain unclear. We present 1.3 mm dust continuum and molecular line observations with the Atacama Large Millimeter/submillimeter Array (ALMA) toward 43 protostellar cores in the Orion Molecular Cloud Complex ($λ$ Orionis, Orion B, and Orion A) with an angular resolution of $\sim$ 0.35" ($\sim$ 140 au). In total, we detect 13 binary/multiple systems. We derive an overall multiplicity frequency (MF) of 28$\%$ $\pm$ 4$\%$ and a companion star fraction (CSF) of 51$\%$ $\pm$ 6$\%$, over a separation range of 300-8900 au. The median separation of companions is about 2100 au. The occurrence of stellar multiplicity may depend on the physical characteristics of the dense cores. Notably, those containing binary/multiple systems tend to show higher gas density and Mach number than cores forming single stars. The integral-shaped filament (ISF) of Orion A giant molecular cloud (GMC), which has the highest gas density and hosts high-mass star formation in its central region (the Orion Nebula cluster), shows the highest MF and CSF among the Orion GMCs. In contrast, the $λ$ Orionis Giant Molecular Cloud (GMC) has a lower MF and CSF than the Orion B and Orion A GMCs, indicating that feedback from HII regions may suppress the formation of multiple systems. We also find that the protostars comprising a binary/multiple system are usually at different evolutionary stages. △ Less

Submitted 9 May, 2022; v1 submitted 13 April, 2022; originally announced April 2022.

Comments: This paper was accepted by APJ. 31 pages and 9 figures

Nobeyama Survey of Inward Motions toward Cores in Orion Identified by SCUBA-2

Authors: Ken'ichi Tatematsu, You-Ting Yeh, Naomi Hirano, Sheng-Yuan Liu, Tie Liu, Somnath Dutta, Dipen Sahu, Neal J. Evans II, Mika Juvela, Hee-Weon Yi, Jeong-Eun Lee, Patricio Sanhueza, Shanghuo Li, David Eden, Gwanjeong Kim, Chin-Fei Lee, Yuefang Wu, Kee-Tae Kim, L. Viktor T'oth, Minho Choi, Miju Kang, Mark A. Thompson, Gary A. Fuller, 20 Di Li, Ke Wang , et al. (6 additional authors not shown)

Abstract: In this study, 36 cores (30 starless and 6 protostellar) identified in Orion were surveyed to search for inward motions. We used the Nobeyama 45 m radio telescope, and mapped the cores in the $J = 1\rightarrow0$ transitions of HCO$^+$, H$^{13}$CO$^+$, N$_2$H$^+$, HNC, and HN$^{13}$C. The asymmetry parameter $δV$, which was the ratio of the difference between the HCO$^+$ and H$^{13}$CO$^+$ peak vel… ▽ More In this study, 36 cores (30 starless and 6 protostellar) identified in Orion were surveyed to search for inward motions. We used the Nobeyama 45 m radio telescope, and mapped the cores in the $J = 1\rightarrow0$ transitions of HCO$^+$, H$^{13}$CO$^+$, N$_2$H$^+$, HNC, and HN$^{13}$C. The asymmetry parameter $δV$, which was the ratio of the difference between the HCO$^+$ and H$^{13}$CO$^+$ peak velocities to the H$^{13}$CO$^+$ line width, was biased toward negative values, suggesting that inward motions were more dominant than outward motions. Three starless cores (10% of all starless cores surveyed) were identified as cores with blue-skewed line profiles (asymmetric profiles with more intense blue-shifted emission), and another two starless cores (7%) were identified as candidate blue-skewed line profiles. The peak velocity difference between HCO$^+$ and H$^{13}$CO$^+$ of them was up to 0.9 km s$^{-1}$, suggesting that some inward motions exceeded the speed of sound for the quiescent gas ($\sim10-17$ K). The mean of $δV$ of the five aforementioned starless cores was derived to be $-$0.5$\pm$0.3. One core, G211.16$-$19.33North3, observed using the ALMA ACA in DCO$^+$ $J = 3\rightarrow2$ exhibited blue-skewed features. Velocity offset in the blue-skewed line profile with a dip in the DCO$^+$ $J = 3\rightarrow2$ line was larger ($\sim 0.5$ km s$^{-1}$) than that in HCO$^+$ $J = 1\rightarrow0$ ($\sim 0.2$ km s$^{-1}$), which may represent gravitational acceleration of inward motions. It seems that this core is at the last stage in the starless phase, judging from the chemical evolution factor version 2.0 (CEF2.0). △ Less

Submitted 24 March, 2022; originally announced March 2022.

Comments: 45 pages, 28 figures, ApJ in press

Journal ref: Astrophysical J. 931 (2022) 33

A low-threshold ultrahigh-energy neutrino search with the Askaryan Radio Array

Authors: P. Allison, S. Archambault, J. J. Beatty, D. Z. Besson, A. Bishop, C. C. Chen, C. H. Chen, P. Chen, Y. C. Chen, B. A. Clark, W. Clay, A. Connolly, L. Cremonesi, P. Dasgupta, J. Davies, S. de Kockere, K. D. de Vries, C. Deaconu, M. A. DuVernois, J. Flaherty, E. Friedman, R. Gaior, J. Hanson, N. Harty, B. Hendricks , et al. (55 additional authors not shown)

Abstract: In the pursuit of the measurement of the still-elusive ultrahigh-energy (UHE) neutrino flux at energies of order EeV, detectors using the in-ice Askaryan radio technique have increasingly targeted lower trigger thresholds. This has led to improved trigger-level sensitivity to UHE neutrinos. Working with data collected by the Askaryan Radio Array (ARA), we search for neutrino candidates at the lowe… ▽ More In the pursuit of the measurement of the still-elusive ultrahigh-energy (UHE) neutrino flux at energies of order EeV, detectors using the in-ice Askaryan radio technique have increasingly targeted lower trigger thresholds. This has led to improved trigger-level sensitivity to UHE neutrinos. Working with data collected by the Askaryan Radio Array (ARA), we search for neutrino candidates at the lowest threshold achieved to date, leading to improved analysis-level sensitivities. A neutrino search on a data set with 208.7~days of livetime from the reduced-threshold fifth ARA station is performed, achieving a 68\% analysis efficiency over all energies on a simulated mixed-composition neutrino flux with an expected background of $0.10_{-0.04}^{+0.06}$ events passing the analysis. We observe one event passing our analysis and proceed to set a neutrino flux limit using a Feldman-Cousins construction. We show that the improved trigger-level sensitivity can be carried through an analysis, motivating the Phased Array triggering technique for use in future radio-detection experiments. We also include a projection using all available data from this detector. Finally, we find that future analyses will benefit from studies of events near the surface to fully understand the background expected for a large-scale detector. △ Less

Submitted 14 February, 2022; originally announced February 2022.

Comments: 15 pages, 8 figures

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- VIII. A search for hot cores by using C$_2$H$_5$CN, CH$_3$OCHO and CH$_3$OH lines

Authors: Sheng-Li Qin, Tie Liu, Xunchuan Liu, Paul F. Goldsmith, Di Li, Qizhou Zhang, Hong-Li Liu, Yuefang Wu, Leonardo Bronfman, Mika Juvela, Chang Won Lee, Guido Garay, Yong Zhang, Jinhua He, Shih-Ying Hsu, Zhi-Qiang Shen, Jeong-Eun Lee, Ke Wang, Ningyu Tang, Mengyao Tang, Chao Zhang, Yinghua Yue, Qiaowei Xue, Shang-Huo Li, Yaping Peng , et al. (7 additional authors not shown)

Abstract: Hot cores characterized by rich lines of complex organic molecules are considered as ideal sites for investigating the physical and chemical environments of massive star formation. We present a search for hot cores by using typical nitrogen- and oxygen-bearing complex organic molecules (C$_2$H$_5$CN, CH$_3$OCHO and CH$_3$OH), based on ALMA Three-millimeter Observations of Massive Star-forming regi… ▽ More Hot cores characterized by rich lines of complex organic molecules are considered as ideal sites for investigating the physical and chemical environments of massive star formation. We present a search for hot cores by using typical nitrogen- and oxygen-bearing complex organic molecules (C$_2$H$_5$CN, CH$_3$OCHO and CH$_3$OH), based on ALMA Three-millimeter Observations of Massive Star-forming regions (ATOMS). The angular resolutions and line sensitivities of the ALMA observations are better than 2 arcsec and 10 mJy/beam, respectively. A total of 60 hot cores are identified with 45 being newly detected, in which the complex organic molecules have high gas temperatures ($>$ 100 K) and small source sizes ($<$ 0.1 pc). So far this is the largest sample of hot cores observed with similar angular resolution and spectral coverage. The observations have also shown nitrogen and oxygen differentiation in both line emission and gas distribution in 29 hot cores. Column densities of CH$_3$OH and CH$_3$OCHO increase as rotation temperatures rise. The column density of CH$_3$OCHO correlates tightly with that of CH$_3$OH. The pathways for production of different species are discussed. Based on the spatial position difference between hot cores and UC~H{\sc ii} regions, we conclude that 24 hot cores are externally heated while the other hot cores are internally heated. The observations presented here will potentially help establish a hot core template for studying massive star formation and astrochemistry. △ Less

Submitted 25 January, 2022; v1 submitted 24 January, 2022; originally announced January 2022.

Comments: 52 pages; Accepted by MNRAS

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): A Hot Corino Survey toward Protostellar Cores in the Orion Cloud

Authors: Shih-Ying Hsu, Sheng-Yuan Liu, Tie Liu, Dipen Sahu, Chin-Fei Lee, Kenichi Tatematsu, Kee-Tae Kim, Naomi Hirano, Yao-Lun Yang, Doug Johnstone, Hongli Liu, Mika Juvela, Leonardo Bronfman, Huei-Ru Vivien Chen, Somnath Dutta, David J. Eden, Kai-Syun Jhan, Yi-Jehng Kuan, Chang Won Lee, Jeong-Eun Lee, Shanghuo Li, Chun-Fan Liu, Sheng-Li Qin, Patricio Sanhueza, Hsien Shang , et al. (3 additional authors not shown)

Abstract: The presence of complex organic molecules (COMs) in the interstellar medium (ISM) is of great interest since it may link to the origin and prevalence of life in the universe. Aiming to investigate the occurrence of COMs and their possible origins, we conducted a chemical census toward a sample of protostellar cores as part of the ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP) project.… ▽ More The presence of complex organic molecules (COMs) in the interstellar medium (ISM) is of great interest since it may link to the origin and prevalence of life in the universe. Aiming to investigate the occurrence of COMs and their possible origins, we conducted a chemical census toward a sample of protostellar cores as part of the ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP) project. We report the detection of 11 hot corino sources, which exhibit compact emissions from warm and abundant COMs, among 56 Class 0/I protostellar cores. All the hot corino sources discovered are likely Class 0 and their sizes of the warm region ($>$ 100 K) are comparable to 100 au. The luminosity of the hot corino sources exhibits positive correlations with the total number of methanol and the extent of its emissions. Such correlations are consistent with the thermal desorption picture for the presence of hot corino and suggest that the lower luminosity (Class 0) sources likely have a smaller region with COMs emissions. With the same sample selection method and detection criteria being applied, the detection rates of the warm methanol in the Orion cloud (15/37) and the Perseus cloud (28/50) are statistically similar when the cloud distances and the limited sample size are considered. Observing the same set of COM transitions will bring a more informative comparison between the cloud properties. △ Less

Submitted 27 March, 2022; v1 submitted 7 January, 2022; originally announced January 2022.

Comments: 34 pages. 14 figures. 1 figure set. 1 machine-readable table. Accepted for publication in ApJ

Analysis of a Tau Neutrino Origin for the Near-Horizon Air Shower Events Observed by the Fourth Flight of the Antarctic Impulsive Transient Antenna (ANITA)

Authors: R. Prechelt, S. A. Wissel, A. Romero-Wolf, C. Burch, P. W. Gorham, P. Allison, J. Alvarez-Muñiz, O. Banerjee, L. Batten, J. J. Beatty, K. Belov, D. Z. Besson, W. R. Binns, V. Bugaev, P. Cao, W. Carvalho Jr., C. H. Chen, P. Chen, Y. Chen, J. M. Clem, A. Connolly, L. Cremonesi, B. Dailey, C. Deaconu, P. F. Dowkontt , et al. (43 additional authors not shown)

Abstract: We study in detail the sensitivity of the Antarctic Impulsive Transient Antenna (ANITA) to possible $ν_τ$ point source fluxes detected via $τ$-lepton-induced air showers. This investigation is framed around the observation of four upward-going extensive air shower events very close to the horizon seen in ANITA-IV. We find that these four upgoing events are not observationally inconsistent with… ▽ More We study in detail the sensitivity of the Antarctic Impulsive Transient Antenna (ANITA) to possible $ν_τ$ point source fluxes detected via $τ$-lepton-induced air showers. This investigation is framed around the observation of four upward-going extensive air shower events very close to the horizon seen in ANITA-IV. We find that these four upgoing events are not observationally inconsistent with $τ$-induced EASs from Earth-skimming $ν_τ$, both in their spectral properties as well as in their observed locations on the sky. These four events, as well as the overall diffuse and point source exposure to Earth-skimming $ν_τ$, are also compared against published ultrahigh-energy neutrino limits from the Pierre Auger Observatory. While none of these four events occurred at sky locations simultaneously visible by Auger, the implied fluence necessary for ANITA to observe these events is in strong tension with limits set by Auger across a wide range of energies and is additionally in tension with ANITA's Askaryan in-ice neutrino channel above $10^{19}$ eV. We conclude by discussing some of the technical challenges with simulating and analyzing these near horizon events and the potential for future observatories to observe similar events. △ Less

Submitted 13 December, 2021; originally announced December 2021.

Comments: 19 pages, 22 figures, will be published in Physical Review D (PRD)

Detection of a dense SiO jet in the evolved protostellar phase

Authors: Somnath Dutta, Chin-Fei Lee, Doug Johnstone, Tie Liu, Naomi Hirano, Sheng-Yuan Liu, Jeong-Eun Lee, Hsien Shang, Ken'ichi Tatematsu, Kee-Tae Kim, Dipen Sahu, Patricio Sanhueza, James Di Francesco, Kai-Syun Jhan, Chang Won Lee, Woojin Kwon, Shanghuo Li, Leonardo Bronfman, Hong-li Liu, Alessio Traficante, Yi-Jehng Kuan, Shih-Ying Hsu, Anthony Moraghan, Chun-Fan Liu, David Eden , et al. (3 additional authors not shown)

Abstract: Jets and outflows trace the accretion history of protostars. High-velocity molecular jets have been observed from several protostars in the early Class\,0 phase of star formation, detected with the high-density tracer SiO. Until now, no clear jet has been detected with SiO emission from isolated evolved Class\,I protostellar systems. We report a prominent dense SiO jet from a Class\,I source G205S… ▽ More Jets and outflows trace the accretion history of protostars. High-velocity molecular jets have been observed from several protostars in the early Class\,0 phase of star formation, detected with the high-density tracer SiO. Until now, no clear jet has been detected with SiO emission from isolated evolved Class\,I protostellar systems. We report a prominent dense SiO jet from a Class\,I source G205S3 (HOPS\,315: T$_{bol}$ $\sim$ 180 K, spectral index $\sim$ 0.417), with a moderately high mass-loss rate ($\sim$ 0.59 $\times$ 10$^{-6}$ M$_\odot$ yr$^{-1}$) estimated from CO emission. Together, these features suggest that G205S3 is still in a high accretion phase, similar to that expected of Class\,0 objects. We compare G205S3 to a representative Class\,0 system G206W2 (HOPS\,399) and literature Class\,0/I sources to explore the possible explanations behind the SiO emission seen at the later phase. We estimate a high inclination angle ($\sim$ 40$^\circ$) for G205S3 from CO emission, which may expose the infrared emission from the central core and mislead the spectral classification. However, the compact 1.3\,mm continuum, C$^{18}$O emission, location in the bolometric luminosity to sub-millimeter fluxes diagram, outflow force ($\sim$ 3.26 $\times$ 10$^{-5}$ M$_\odot$km s$^{-1}$/yr) are also analogous to that of Class\,I systems. We thus consider G205S3 to be at the very early phase of Class\,I, and in the late phase of ``high-accretion". The episodic ejection could be due to the presence of an unknown binary, a planetary companion, or dense clumps, where the required mass for such high accretion could be supplied by a massive circumbinary disk. △ Less

Submitted 26 October, 2021; originally announced October 2021.

Comments: 13 pages, 5 figures, Accepted for publication in the Astrophysical Journal

Planck Galactic Cold Clumps at High Galactic Latitude-A Study with CO Lines

Authors: Fengwei Xu, Yuefang Wu, Tie Liu, Xunchuan Liu, Chao Zhang, Jarken Esimbek, Sheng-Li Qin, Di Li, Ke Wang, Jinghua Yuan, Fanyi Meng, Tianwei Zhang, David Eden, K. Tatematsu, Neal J. Evans, Paul. F. Goldsmith, Qizhou Zhang, C. Henkel, Hee-Weon Yi, Jeong-Eun Lee, Mika Saajasto, Gwangeong Kim, Mika Juvela, Dipen Sahu, Shin-Ying Hsu , et al. (6 additional authors not shown)

Abstract: Gas at high Galactic latitude is a relatively little-noticed component of the interstellar medium. In an effort to address this, forty-one Planck Galactic Cold Clumps at high Galactic latitude (HGal; $|b|>25^{\circ}$) were observed in $^{12}$CO, $^{13}$CO and C$^{18}$O J=1-0 lines, using the Purple Mountain Observatory 13.7-m telescope. $^{12}$CO (1-0) and $^{13}$CO (1-0) emission was detected in… ▽ More Gas at high Galactic latitude is a relatively little-noticed component of the interstellar medium. In an effort to address this, forty-one Planck Galactic Cold Clumps at high Galactic latitude (HGal; $|b|>25^{\circ}$) were observed in $^{12}$CO, $^{13}$CO and C$^{18}$O J=1-0 lines, using the Purple Mountain Observatory 13.7-m telescope. $^{12}$CO (1-0) and $^{13}$CO (1-0) emission was detected in all clumps while C$^{18}$O (1-0) emission was only seen in sixteen clumps. The highest and average latitudes are $71.4^{\circ}$ and $37.8^{\circ}$, respectively. Fifty-one velocity components were obtained and then each was identified as a single clump. Thirty-three clumps were further mapped at 1$^\prime$ resolution and 54 dense cores were extracted. Among dense cores, the average excitation temperature $T_{\mathrm{ex}}$ of $^{12}$CO is 10.3 K. The average line widths of thermal and non-thermal velocity dispersions are $0.19$ km s$^{-1}$ and $0.46$ km s$^{-1}$ respectively, suggesting that these cores are dominated by turbulence. Distances of the HGal clumps given by Gaia dust reddening are about $120-360$ pc. The ratio of $X_{13}$/$X_{18}$ is significantly higher than that in the solar neighbourhood, implying that HGal gas has a different star formation history compared to the gas in the Galactic disk. HGal cores with sizes from $0.01-0.1$ pc show no notable Larson's relation and the turbulence remains supersonic down to a scale of slightly below $0.1$ pc. None of the HGal cores which bear masses from 0.01-1 $M_{\odot}$ are gravitationally bound and all appear to be confined by outer pressure. △ Less

Submitted 20 July, 2021; v1 submitted 17 July, 2021; originally announced July 2021.

Comments: 35 pages, 13 figures

Triboelectric Backgrounds to radio-based UHE Neutrino Exeperiments

Authors: J. A. Aguilar, A. Anker, P. Allison, S. Archambault, P. Baldi, S. W. Barwick, J. J. Beatty, J. Beise, D. Besson, A. Bishop, E. Bondarev, O. Botner, S. Bouma, S. Buitink, M. Cataldo, C. C. Chen, C. H. Chen, P. Chen, Y. C. Chen, B. A. Clark, W. Clay, Z. Curtis-Ginsberg, A. Connolly, P. Dasgupta, S. de Kockere , et al. (92 additional authors not shown)

Abstract: The proposed IceCube-Gen2 (ICG2) seeks to instrument ~500 sq. km of Antarctic ice near the geographic South Pole with radio antennas, in order to observe the highest energy (E>1 EeV) neutrinos in the Universe. To this end, ICG2 will use the impulsive radio-frequency (RF) signal produced by neutrino interactions in polar ice caps. In such experiments, rare single event candidates must be unambiguou… ▽ More The proposed IceCube-Gen2 (ICG2) seeks to instrument ~500 sq. km of Antarctic ice near the geographic South Pole with radio antennas, in order to observe the highest energy (E>1 EeV) neutrinos in the Universe. To this end, ICG2 will use the impulsive radio-frequency (RF) signal produced by neutrino interactions in polar ice caps. In such experiments, rare single event candidates must be unambiguously separated from background; to date, signal identification strategies primarily reject thermal noise and anthropogenic backgrounds. Here, we consider the possibility that fake neutrino signals may also be naturally generated via the 'triboelectric effect'. This broadly includes any process in which force applied at a boundary layer results in displacement of surface charge, generating a potential difference ΔV. Wind blowing over granular surfaces such as snow can induce such a ΔV, with subsequent discharge. Discharges over nanosecond-timescales can then lead to RF emissions at characteristic MHz-GHz frequencies. We find that such backgrounds are evident in the several neutrino experiments considered, and are generally characterized by: a) a threshold wind velocity which likely depends on the experimental signal trigger threshold and layout; for the experiments considered herein, this value is typically O(10 m/s), b) frequency spectra generally shifted to the low-end of the frequency regime to which current radio experiments are typically sensitive (100-200 MHz), c) for the strongest background signals, an apparent preference for discharges from above-surface structures, although the presence of more isotropic, lower amplitude triboelectric discharges cannot be excluded. △ Less

Submitted 10 August, 2022; v1 submitted 10 March, 2021; originally announced March 2021.

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Detection of extremely high density compact structure of prestellar cores and multiple substructures within

Authors: Dipen Sahu, Sheng-Yuan Liu, Tie Liu, Neal J. Evans II, Naomi Hirano, Ken'ichi Tatematsu, Chin-Fei Lee, Kee-Tae Kim, Somnath Dutta, Dana Alina, Leonardo Bronfman, Maria Cunningham, David J. Eden, Guido Garay, Paul F. Goldsmith, Jinhua He, Shih-Ying Hsu, Kai-Syun Jhan, Doug Johnstone, Mika Juvela, Gwanjeong Kim, Yi-Jehng Kuan, Woojin Kwon, Chang Won Lee, Jeong-Eun Lee , et al. (16 additional authors not shown)

Abstract: Prestellar cores are self-gravitating dense and cold structures within molecular clouds where future stars are born. They are expected, at the stage of transitioning to the protostellar phase, to harbor centrally concentrated dense (sub)structures that will seed the formation of a new star or the binary/multiple stellar systems. Characterizing this critical stage of evolution is key to our underst… ▽ More Prestellar cores are self-gravitating dense and cold structures within molecular clouds where future stars are born. They are expected, at the stage of transitioning to the protostellar phase, to harbor centrally concentrated dense (sub)structures that will seed the formation of a new star or the binary/multiple stellar systems. Characterizing this critical stage of evolution is key to our understanding of star formation. In this work, we report the detection of high density (sub)structures on the thousand-au scale in a sample of dense prestellar cores. Through our recent ALMA observations towards the Orion molecular cloud, we have found five extremely dense prestellar cores, which have centrally concentrated regions $\sim$ 2000 au in size, and several $10^7$ $cm^{-3}$ in average density. Masses of these centrally dense regions are in the range of 0.30 to 6.89 M$_\odot$. {\it For the first time}, our higher resolution observations (0.8$'' \sim $ 320 au) further reveal that one of the cores shows clear signatures of fragmentation; such individual substructures/fragments have sizes of 800 -1700 au, masses of 0.08 to 0.84 M$_\odot$, densities of $2 - 8\times 10^7$ $cm^{-3}$ and separations of $\sim 1200$ au. The substructures are massive enough ($\gtrsim 0.1~M_\odot$) to form young stellar objects and are likely examples of the earliest stage of stellar embryos which can lead to widely ($\sim$ 1200 au) separated multiple systems. △ Less

Submitted 12 February, 2023; v1 submitted 15 December, 2020; originally announced December 2020.

Comments: Published in The Astrophysical Journal Letters (ApJL)

Commissioning of Namakanui on the JCMT

Authors: Izumi Mizuno, Per Friberg, Ryan Berthold, Harriet Parsons, Chih-Chiang Han, Alexis Acohido, Graham Bell, David Berry, Dan Bintley, Ming-Tang Chen, Alyssa Clark, Jamie Cookson, Vernon Demattos, Jessica Dempsey, Jason Fleck, Kuo-chieh Fu, Miriam Fuchs, Sarah Graves, Paul Ho, Sung-Po Hsu, YauDe Huang, Xue-Jian Jiang, Derek Kubo, JohnKuroda, Shaoliang Li , et al. (17 additional authors not shown)

Abstract: Namakanui is an instrument containing three inserts in an ALMA type Dewar. The three inserts are Alaihi, Uu and Aweoweo operating around 86, 230 and 345GHz. The receiver is being commissioned on the JCMT. It will be used for both Single dish and VLBI observations. We will present commissioning results and the system. Namakanui is an instrument containing three inserts in an ALMA type Dewar. The three inserts are Alaihi, Uu and Aweoweo operating around 86, 230 and 345GHz. The receiver is being commissioned on the JCMT. It will be used for both Single dish and VLBI observations. We will present commissioning results and the system. △ Less

Submitted 14 December, 2020; originally announced December 2020.

Comments: 19 pages, 16 figures, Proceedings of SPIE

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP) II. Survey overview: a first look at 1.3 mm continuum maps and molecular outflows

Authors: Somnath Dutta, Chin-Fei Lee, Tie Liu, Naomi Hirano, Sheng-Yuan Liu, Kenichi Tatematsu, Kee-Tae Kim, Hsien Shang, Dipen Sahu, Gwanjeong Kim, Anthony Moraghan, Kai-Syun Jhan, Shih-Ying Hsu, Neal J. Evans, Doug Johnstone, Derek Ward-Thompson, Yi-Jehng Kuan, Chang Won Lee, Jeong-Eun Lee, Alessio Traficante, Mika Juvela, Charlotte Vastel, Qizhou Zhang, Patricio Sanhueza, Archana Soam , et al. (10 additional authors not shown)

Abstract: Planck Galactic Cold Clumps (PGCCs) are contemplated to be the ideal targets to probe the early phases of star formation. We have conducted a survey of 72 young dense cores inside PGCCs in the Orion complex with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3\,mm (band 6) using three different configurations (resolutions $\sim$ 0$\farcs$35, 1$\farcs$0, and 7$\farcs$0) to statistical… ▽ More Planck Galactic Cold Clumps (PGCCs) are contemplated to be the ideal targets to probe the early phases of star formation. We have conducted a survey of 72 young dense cores inside PGCCs in the Orion complex with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3\,mm (band 6) using three different configurations (resolutions $\sim$ 0$\farcs$35, 1$\farcs$0, and 7$\farcs$0) to statistically investigate their evolutionary stages and sub-structures. We have obtained images of the 1.3\,mm continuum and molecular line emission ($^{12}$CO, and SiO) at an angular resolution of $\sim$ 0$\farcs$35 ($\sim$ 140\,au) with the combined arrays. We find 70 substructures within 48 detected dense cores with median dust-mass $\sim$ 0.093\,M$_{\sun}$ and deconvolved size $\sim$ 0$\farcs$27. Dense substructures are clearly detected within the central 1000\,au of four candidate prestellar cores. The sizes and masses of the substructures in continuum emission are found to be significantly reduced with protostellar evolution from Class\,0 to Class\,I. We also study the evolutionary change in the outflow characteristics through the course of protostellar mass accretion. A total of 37 sources exhibit CO outflows, and 20 ($>$50\%) show high-velocity jets in SiO. The CO velocity-extents ($Δ$Vs) span from 4 to 110 km/s with outflow cavity opening angle width at 400\,au ranging from $[Θ_{obs}]_{400}$ $\sim$ 0$\farcs$6 to 3$\farcs$9, which corresponds to 33$\fdg$4$-$125$\fdg$7. For the majority of the outflow sources, the $Δ$Vs show a positive correlation with $[Θ_{obs}]_{400}$, suggesting that as protostars undergo gravitational collapse, the cavity opening of a protostellar outflow widens and the protostars possibly generate more energetic outflows. △ Less

Submitted 27 October, 2020; originally announced October 2020.

Comments: 43 pages, 25 figures (14 in the main text, 9 in the appendix), accepted for publication in the Astrophysical Journal Supplement Series (ApJS)

A search for ultrahigh-energy neutrinos associated with astrophysical sources using the third flight of ANITA

Authors: C. Deaconu, L. Batten, P. Allison, O. Banerjee, J. J. Beatty, K. Belov, D. Z. Besson, W. R. Binns, V. Bugaev, P. Cao, C. H. Chen, P. Chen, Y. Chen, J. M. Clem, A. Connolly, L. Cremonesi, B. Dailey, P. F. Dowkontt, B. D. Fox, J. W. H. Gordon, P. W. Gorham, C. Hast, B. Hill, S. Y. Hsu, J. J. Huang , et al. (38 additional authors not shown)

Abstract: The ANtarctic Impulsive Transient Antenna (ANITA) long-duration balloon experiment is sensitive to interactions of ultra high-energy (E > 10^{18} eV) neutrinos in the Antarctic ice sheet. The third flight of ANITA, lasting 22 days, began in December 2014. We develop a methodology to search for energetic neutrinos spatially and temporally coincident with potential source classes in ANITA data. This… ▽ More The ANtarctic Impulsive Transient Antenna (ANITA) long-duration balloon experiment is sensitive to interactions of ultra high-energy (E > 10^{18} eV) neutrinos in the Antarctic ice sheet. The third flight of ANITA, lasting 22 days, began in December 2014. We develop a methodology to search for energetic neutrinos spatially and temporally coincident with potential source classes in ANITA data. This methodology is applied to several source classes: the TXS 0506+056 blazar and NGC 1068, the first potential TeV neutrino sources identified by IceCube, flaring high-energy blazars reported by the Fermi All-Sky Variability Analysis, gamma-ray bursts, and supernovae. Among searches within the five source classes, one candidate was identified as associated with SN 2015D, although not at a statistically significant level. We proceed to place upper limits on the source classes. We further comment on potential applications of this methodology to more sensitive future instruments. △ Less

Submitted 15 March, 2021; v1 submitted 6 October, 2020; originally announced October 2020.

Comments: 23 pages, 7 figures, version accepted to JCAP

Unusual Near-horizon Cosmic-ray-like Events Observed by ANITA-IV

Authors: ANITA Collaboration, P. W. Gorham, A. Ludwig, C. Deaconu, P. Cao, P. Allison, O. Banerjee, L. Batten, D. Bhattacharya, J. J. Beatty, K. Belov, W. R. Binns, V. Bugaev, C. H. Chen, P. Chen, Y. Chen, J. M. Clem, L. Cremonesi, B. Dailey, P. F. Dowkontt, B. D. Fox, J. W. H. Gordon, C. Hast, B. Hill, S. Y. Hsu , et al. (35 additional authors not shown)

Abstract: ANITA's fourth long-duration balloon flight in late 2016 detected 29 cosmic-ray (CR)-like events on a background of $0.37^{+0.27}_{-0.17}$ anthropogenic events. CRs are mainly seen in reflection off the Antarctic ice sheets, creating a characteristic phase-inverted waveform polarity. However, four of the below-horizon CR-like events show anomalous non-inverted polarity, a $p = 5.3 \times 10^{-4}$… ▽ More ANITA's fourth long-duration balloon flight in late 2016 detected 29 cosmic-ray (CR)-like events on a background of $0.37^{+0.27}_{-0.17}$ anthropogenic events. CRs are mainly seen in reflection off the Antarctic ice sheets, creating a characteristic phase-inverted waveform polarity. However, four of the below-horizon CR-like events show anomalous non-inverted polarity, a $p = 5.3 \times 10^{-4}$ chance if due to background. All anomalous events are from locations near the horizon; ANITA-IV observed no steeply-upcoming anomalous events similar to the two such events seen in prior flights. △ Less

Submitted 19 November, 2020; v1 submitted 13 August, 2020; originally announced August 2020.

Comments: 6 pages, 4 figures, to appear in Physical Review Letters. Supplemental material (reference 17) available from corresponding author

Journal ref: Phys. Rev. Lett. 126, 071103 (2021)

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): I. Detection of New Hot Corinos with ACA

Authors: Shih-Ying Hsu, Sheng-Yuan Liu, Tie Liu, Dipen Sahu, Naomi Hirano, Chin-Fei Lee, Kenichi Tatematsu, Gwanjeong Kim, Mika Juvela, Patricio Sanhueza, Jinhua He, Doug Johnstone, Sheng-Li Qin, Leonardo J. Bronfman, Huei-Ru Chen, Somnath Dutta, David Eden, Kai-Syun Jhan, Kee-Tae Kim, Yi-Jehng Kuan, Woojin Kwon, Chang Won Lee, Jeong-Eun Lee, Anthony Moraghan, Mark Rawlings , et al. (7 additional authors not shown)

Abstract: We report the detection of four new hot corino sources, G211.47-19.27S, G208.68-19.20N1, G210.49-19.79W and G192.12-11.10 from a survey study of Planck Galactic Cold Clumps in the Orion Molecular Cloud Complex with the Atacama Compact Array (ACA). Three sources had been identified as low mass Class 0 protostars in the Herschel Orion Protostar Survey (HOPS). One source in the lambda Orionis region… ▽ More We report the detection of four new hot corino sources, G211.47-19.27S, G208.68-19.20N1, G210.49-19.79W and G192.12-11.10 from a survey study of Planck Galactic Cold Clumps in the Orion Molecular Cloud Complex with the Atacama Compact Array (ACA). Three sources had been identified as low mass Class 0 protostars in the Herschel Orion Protostar Survey (HOPS). One source in the lambda Orionis region is firstly reported as a protostellar core. We have observed abundant complex organic molecules (COMs), primarily methanol but also other oxygen-bearing COMs (in G211.47-19.27S and G208.68-19.20N1) and the molecule of prebiotic interest NH2CHO (in G211.47-19.27S), signifying the presence of hot corinos. While our spatial resolution is not sufficient for resolving most of the molecular emission structure, the large linewidth and high rotational temperature of COMs suggest that they likely reside in the hotter and innermost region immediately surrounding the protostar. In G211.47-19.27S, the D/H ratio of methanol ([CH2DOH]/[CH3OH]) and the 12C/13C ratio of methanol ([CH3OH]/[13CH3OH]) are comparable to those of other hot corinos. Hydrocarbons and long carbon-chain molecules such as c-C3H2 and HCCCN are also detected in the four sources, likely tracing the outer and cooler molecular envelopes. △ Less

Submitted 29 June, 2020; originally announced June 2020.

Comments: 37 pages, 51 figures, to be published in ApJ