Showing 1–50 of 170 results for author: Gao, J

Revisiting Mars' Induced Magnetic Field and Clock Angle Departures under Real-Time Upstream Solar Wind Conditions

Authors: Zhihao Cheng, Chi Zhang, Chuanfei Dong, Hongyang Zhou, Jiawei Gao, Abigail Tadlock, Xinmin Li, Liang Wang

Abstract: Mars lacks a global intrinsic dipole magnetic field, but its interaction with the solar wind generates a global induced magnetosphere. Until now, most studies have relied on single-spacecraft measurements, which could not simultaneously capture upstream solar wind conditions and the induced magnetic fields, thereby limiting our understanding of the system. Here, we statistically re-examine the pro… ▽ More Mars lacks a global intrinsic dipole magnetic field, but its interaction with the solar wind generates a global induced magnetosphere. Until now, most studies have relied on single-spacecraft measurements, which could not simultaneously capture upstream solar wind conditions and the induced magnetic fields, thereby limiting our understanding of the system. Here, we statistically re-examine the properties of Mars' induced magnetic field by incorporating, for the first time, real-time upstream solar wind conditions from the coordinated MAVEN and Tianwen-1 observations. Our results are show that both solar wind dynamic pressure and the interplanetary magnetic field (IMF) magnitude enhance the strength of the induced magnetic field, but they exert opposite effects on the compression ratio: higher dynamic pressure strengthens compression, while stronger IMF weakens it. The induced field is stronger under quasi-perpendicular IMF conditions compared with quasi-parallel IMF, reflecting a stronger mass-loading effect. We further investigate the clock angle departures of the induced fields. They remain relatively small in the magnetosheath near the bow shock, increase gradually toward the induced magnetosphere, and become significantly larger within the induced magnetosphere. In addition, clock angle departures are strongly enhanced under quasi-parallel IMF conditions. Their dependence on upstream drivers further shows that, within the magnetosheath, clock angle departures are minimized under low dynamic pressure, high IMF magnitude, and low Alfven Mach number conditions. These results may enhance our understanding of solar wind interaction with Mars, and highlight the critical role of multi-point observations. △ Less

Submitted 21 December, 2025; originally announced December 2025.

Comments: 27 pages, 8 figures, accepted for publication in Journal of Geophysical Research: Space Physics

Physics-Informed Neural Networks for Modeling the Martian Induced Magnetosphere

Authors: Jiawei Gao, Chuanfei Dong, Chi Zhang, Yilan Qin, Simin Shekarpaz, Xinmin Li, Liang Wang, Hongyang Zhou, Abigail Tadlock

Abstract: Understanding the magnetic field environment around Mars and its response to upstream solar wind conditions provide key insights into the processes driving atmospheric ion escape. To date, global models of Martian induced magnetosphere have been exclusively physics-based, relying on computationally intensive simulations. For the first time, we develop a data-driven model of the Martian induced mag… ▽ More Understanding the magnetic field environment around Mars and its response to upstream solar wind conditions provide key insights into the processes driving atmospheric ion escape. To date, global models of Martian induced magnetosphere have been exclusively physics-based, relying on computationally intensive simulations. For the first time, we develop a data-driven model of the Martian induced magnetospheric magnetic field using Physics-Informed Neural Network (PINN) combined with MAVEN observations and physical laws. Trained under varying solar wind conditions, including B_IMF, P_SW, and θ_cone, the data-driven model accurately reconstructs the three-dimensional magnetic field configuration and its variability in response to upstream solar wind drivers. Based on the PINN results, we identify key dependencies of magnetic field configuration on solar wind parameters, including the hemispheric asymmetries of the draped field line strength in the Mars-Solar-Electric coordinates. These findings demonstrate the capability of PINNs to reconstruct complex magnetic field structures in the Martian induced magnetosphere, thereby offering a promising tool for advancing studies of solar wind-Mars interactions. △ Less

Submitted 17 December, 2025; originally announced December 2025.

First Associated Neutrino Search for a Failed Supernova Candidate with Super-Kamiokande

Authors: F. Nakanishi, K. Abe, S. Abe, Y. Asaoka, M. Harada, Y. Hayato, K. Hiraide, K. Hosokawa, T. H. Hung, K. Ieki, M. Ikeda, J. Kameda, Y. Kanemura, Y. Kataoka, S. Miki, S. Mine, M. Miura, S. Moriyama, M. Nakahata, S. Nakayama, Y. Noguchi, G. Pronost, K. Sato, H. Sekiya, M. Shiozawa , et al. (221 additional authors not shown)

Abstract: In 2024, a failed supernova candidate, M31-2014-DS1, was reported in the Andromeda galaxy (M31), located at a distance of approximately 770 kpc. In this paper, we search for neutrinos from this failed supernova using data from Super-Kamiokande (SK). Based on the estimated time of black hole formation inferred from optical and infrared observations, we define a search window for neutrino events in… ▽ More In 2024, a failed supernova candidate, M31-2014-DS1, was reported in the Andromeda galaxy (M31), located at a distance of approximately 770 kpc. In this paper, we search for neutrinos from this failed supernova using data from Super-Kamiokande (SK). Based on the estimated time of black hole formation inferred from optical and infrared observations, we define a search window for neutrino events in the SK data. Using this window, we develop a dedicated analysis method for failed supernovae and apply it to M31-2014-DS1, by conducting a cluster search using the timing and energy information of candidate events. No significant neutrino excess is observed within the search region. Consequently, we place an upper limit on the electron antineutrino luminosity from M31-2014-DS1 and discuss its implications for various failed SN models and their neutrino emission characteristics. Despite the 18 MeV threshold adopted to suppress backgrounds, the search remains sufficiently sensitive to constrain the Shen-TM1 EOS, yielding a 90% confidence level upper limit of 1.76 \times 10^{53} erg on the electron antineutrino luminosity, slightly above the expected value of 1.35 \times 10^{53} erg. △ Less

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

Comments: 11 pages, 4 figures, and 1 table

Search for Diffuse Supernova Neutrino Background with 956.2 days of Super-Kamiokande Gadolinium Dataset

Authors: K. Abe, S. Abe, Y. Asaoka, M. Harada, Y. Hayato, K. Hiraide, K. Hosokawa, T. H. Hung, K. Ieki, M. Ikeda, J. Kameda, Y. Kanemura, Y. Kataoka, S. Miki, S. Mine, M. Miura, S. Moriyama, M. Nakahata, S. Nakayama, Y. Noguchi, G. Pronost, K. Sato, H. Sekiya, R. Shinoda, M. Shiozawa , et al. (223 additional authors not shown)

Abstract: We report the search result for the Diffuse Supernova Neutrino Background (DSNB) in neutrino energies beyond 9.3~MeV in the gadolinium-loaded Super-Kamiokande (SK) detector with $22,500\times956.2$$~\rm m^3\cdot day$ exposure. %$22.5{\rm k}\times956.2$$~\rm m^3\cdot day$ exposure. Starting in the summer of 2020, SK introduced 0.01\% gadolinium (Gd) by mass into its ultra-pure water to enhance the… ▽ More We report the search result for the Diffuse Supernova Neutrino Background (DSNB) in neutrino energies beyond 9.3~MeV in the gadolinium-loaded Super-Kamiokande (SK) detector with $22,500\times956.2$$~\rm m^3\cdot day$ exposure. %$22.5{\rm k}\times956.2$$~\rm m^3\cdot day$ exposure. Starting in the summer of 2020, SK introduced 0.01\% gadolinium (Gd) by mass into its ultra-pure water to enhance the neutron capture signal, termed the SK-VI phase. This was followed by a 0.03\% Gd-loading in 2022, a phase referred to as SK-VII. We then conducted a DSNB search using 552.2~days of SK-VI data and 404.0~days of SK-VII data through September 2023. This analysis includes several new features, such as two new machine-learning neutron detection algorithms with Gd, an improved atmospheric background reduction technique, and two parallel statistical approaches. No significant excess over background predictions was found in a DSNB spectrum-independent analysis, and 90\% C.L. upper limits on the astrophysical electron anti-neutrino flux were set. Additionally, a spectral fitting result exhibited a $\sim1.2σ$ disagreement with a null DSNB hypothesis, comparable to a previous result from 5823~days of all SK pure water phases. △ Less

Submitted 3 November, 2025; originally announced November 2025.

Magnetic Field and Plasma Asymmetries Between the Martian Quasi-Perpendicular and Quasi-Parallel Magnetosheaths

Authors: Abigail Tadlock, Chuanfei Dong, Chi Zhang, Markus Franz, Hongyang Zhou, Jiawei Gao

Abstract: The Martian magnetosheath acts as a conduit for mass and energy transfer between the upstream solar wind and its induced magnetosphere. However, our understanding of its global properties remains limited. Using nine years of data from NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we performed a quantitative statistical analysis to explore the spatial distribution of the magnetic f… ▽ More The Martian magnetosheath acts as a conduit for mass and energy transfer between the upstream solar wind and its induced magnetosphere. However, our understanding of its global properties remains limited. Using nine years of data from NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we performed a quantitative statistical analysis to explore the spatial distribution of the magnetic fields, solar wind and planetary ions in the magnetosheath. We discovered significant asymmetries in the magnetic field, solar wind protons, and planetary ions between the quasi-perpendicular and quasi-parallel magnetosheaths. The asymmetries in the Martian magnetosheath exhibit both similarities and differences compared to those in the Earth's and Venus' magnetosheaths. These results indicate that the Martian magnetosheath is distinctly shaped by both shock geometry and planetary ions. △ Less

Submitted 8 September, 2025; originally announced September 2025.

Comments: 16 pages, 4 figures, accepted for publication in Geophysical Research Letters

Journal ref: Geophysical Research Letters, 52, e2025GL118172 (2025)

Constraints on transition redshift utilizing the latest H(z) measurements and comments on the Hubble tension

Authors: Jianping Hu, Xuandong Jia, DaoHong Gao, Jiaze Gao, Baoquan Gao, Fayin Wang

Abstract: The motivation of this paper is to obtain reliable constraints of transition redshift ($z_{ztr}$) and, in combination with the evolution of the Hubble constant ($H_{0}$) that could alleviate the Hubble tension, discuss the possible origin of the tension. Utilizing the latest H(z) measurements and different methods ($Λ$CDM model, Cosmography, and Gaussian process method), we investigated the impact… ▽ More The motivation of this paper is to obtain reliable constraints of transition redshift ($z_{ztr}$) and, in combination with the evolution of the Hubble constant ($H_{0}$) that could alleviate the Hubble tension, discuss the possible origin of the tension. Utilizing the latest H(z) measurements and different methods ($Λ$CDM model, Cosmography, and Gaussian process method), we investigated the impact of methodology and dataset on $z_{ztr}$ constraints, and find that the choice of method has a greater impact on $z_{tr}$ than the observations themselves. Through a statistical analysis of the $z_{ztr}$ constraints from 2004 to 2024, we find that total $z_{tr}$ constraints (2004$-$2024) can be well described by a Gaussian function with the mean value 0.65 and the standard deviation 0.16; that is, $\bar{z}_{tr}$(all) = 0.65 $\pm$ 0.16. And we confirmed that both dataset and methodology can indeed significantly affect the final constraints. The screened $z_{tr}$ constraints with free $H_{0}$ gives a new result $\bar{z}_{tr}$(free) = 0.64 $\pm$ 0.16. Coincidentally, the $z_{tr}$ results overlap with the initial moment of $H_{0}$ evolution ($H_{0}$ value starts to deviate from the Planck result). This may suggest that the Hubble tension might be closely related to this particular period in the evolution of the Universe. △ Less

Submitted 7 August, 2025; originally announced August 2025.

Comments: 14 pages, 8 figures, 5 tables. Accepted for publication in MNRAS

Metalens-coupled terahertz NbN hot electron bolometer mixer

Authors: D. Ren, J. R. G. Silva, S. Cremasco, Z. Zhao, W. Ji, J. de Graaff, A. J. L. Adam, J. R. Gao

Abstract: Enabled by planarized phase engineering, metalenses based on metasurfaces offer compact and scalable solutions for applications such as sensing, imaging, and virtual reality. They are particularly attractive for multi-pixel, large-scale heterodyne focal plane arrays in space observatories, where a flat metalens array on a silicon wafer can replace individual lenses, greatly simplifying system inte… ▽ More Enabled by planarized phase engineering, metalenses based on metasurfaces offer compact and scalable solutions for applications such as sensing, imaging, and virtual reality. They are particularly attractive for multi-pixel, large-scale heterodyne focal plane arrays in space observatories, where a flat metalens array on a silicon wafer can replace individual lenses, greatly simplifying system integration and beam alignment. In this work, we demonstrate, for the first time, a superconducting niobium nitride (NbN) hot electron bolometer (HEB) mixer coupled with a silicon-based metalens operating at terahertz frequencies. The metalens phase profile was derived from a finite-size Gaussian beam source using the Rayleigh-Sommerfeld diffraction integral, and its focusing behavior was validated through 2D simulation. Experimentally, the metalens-coupled NbN HEB receiver exhibited a noise temperature of 1800 K at 1.63 THz. The power coupling efficiency from free space to the mixer via the metalens was measured to be 25 %. Measured far-field beam profiles are Gaussian-like with sidelobes below -14 dB. These results demonstrate the feasibility of integrating metalenses with HEB mixers for THz detection, offering a scalable path for compact focal plane arrays in space-based THz instrumentation. △ Less

Submitted 22 July, 2025; originally announced July 2025.

Introduction to the Chinese Space Station Survey Telescope (CSST)

Authors: CSST Collaboration, Yan Gong, Haitao Miao, Hu Zhan, Zhao-Yu Li, Jinyi Shangguan, Haining Li, Chao Liu, Xuefei Chen, Haibo Yuan, Jilin Zhou, Hui-Gen Liu, Cong Yu, Jianghui Ji, Zhaoxiang Qi, Jiacheng Liu, Zigao Dai, Xiaofeng Wang, Zhenya Zheng, Lei Hao, Jiangpei Dou, Yiping Ao, Zhenhui Lin, Kun Zhang, Wei Wang , et al. (97 additional authors not shown)

Abstract: The Chinese Space Station Survey Telescope (CSST) is an upcoming Stage-IV sky survey telescope, distinguished by its large field of view (FoV), high image quality, and multi-band observation capabilities. It can simultaneously conduct precise measurements of the Universe by performing multi-color photometric imaging and slitless spectroscopic surveys. The CSST is equipped with five scientific inst… ▽ More The Chinese Space Station Survey Telescope (CSST) is an upcoming Stage-IV sky survey telescope, distinguished by its large field of view (FoV), high image quality, and multi-band observation capabilities. It can simultaneously conduct precise measurements of the Universe by performing multi-color photometric imaging and slitless spectroscopic surveys. The CSST is equipped with five scientific instruments, i.e. Multi-band Imaging and Slitless Spectroscopy Survey Camera (SC), Multi-Channel Imager (MCI), Integral Field Spectrograph (IFS), Cool Planet Imaging Coronagraph (CPI-C), and THz Spectrometer (TS). Using these instruments, CSST is expected to make significant contributions and discoveries across various astronomical fields, including cosmology, galaxies and active galactic nuclei (AGN), the Milky Way and nearby galaxies, stars, exoplanets, Solar System objects, astrometry, and transients and variable sources. This review aims to provide a comprehensive overview of the CSST instruments, observational capabilities, data products, and scientific potential. △ Less

Submitted 19 September, 2025; v1 submitted 6 July, 2025; originally announced July 2025.

Comments: 48 pages, 12 figures, 1 table. Accepted for publication in SCIENCE CHINA Physics, Mechanics & Astronomy

The Mini-SiTian Array: Light Curves Analysis of Asteroids

Authors: Zhaoxing Liu, Jian Gao, Hongrui Gu, Yang Huang, Shaoming Hu, Hu Zou, Keyu Xing, Hao Huang, Zehao Zhang

Abstract: The SiTian project, with its vast field of view, will become an ideal platform for asteroid scientific research. In this study, we develop a pipeline to analyze the photometry of asteroids and derive their periods from the data collected by the SiTian pathfinder project Mini-SiTian (MST). The pipeline is applied to the MST f02 region, a MST test region with a sky area of… ▽ More The SiTian project, with its vast field of view, will become an ideal platform for asteroid scientific research. In this study, we develop a pipeline to analyze the photometry of asteroids and derive their periods from the data collected by the SiTian pathfinder project Mini-SiTian (MST). The pipeline is applied to the MST f02 region, a MST test region with a sky area of $2.29^{\circ} \times 1.53^{\circ}$. Rotation periods of 22 asteroids are derived by the obtained light curves analysis. Among them, there are 8 asteroids available in the Asteroid Lightcurve Photometry Database (ALCDEF), and 6 of them with more photometric points ($>$200) have similar period parameters as the ones in ALCDEF. Additionally, the periods for 14 of these asteroids are newly obtained and are not listed in ALCDEF. This study demonstrates the feasibility of asteroid photometric research by the SiTian project. It shows that future observations from the SiTian project will provide even more photometry of asteroids, significantly increasing the number of available light curves. The potential vast photometric data of asteroids will help us to further understand the physics of asteroids, their material composition, and the formation and evolution of the solar system. △ Less

Submitted 2 April, 2025; originally announced April 2025.

Comments: 14 pages, 7 figures, 4 tables. Accepted for publication in a special issue of Research in Astronomy and Astrophysics on the Mini-SiTian Array

Extinction Distributions in Nearby Star-resolved Galaxies. I. M31

Authors: Yuxi Wang, Jian Gao, Yi Ren, Bingqiu Chen

Abstract: An extinction distribution of the Andromeda Galaxy (M31) is constructed with member stars as tracers by fitting multiband photometric data from UKIRT/WFCAM, PS1, and Gaia DR3. The resulting extinction distribution covers approximately 10 deg$^2$ of M31 with a resolution of approximately 50 arcsec, providing the largest coverage to date based on stellar observations. The derived average extinction,… ▽ More An extinction distribution of the Andromeda Galaxy (M31) is constructed with member stars as tracers by fitting multiband photometric data from UKIRT/WFCAM, PS1, and Gaia DR3. The resulting extinction distribution covers approximately 10 deg$^2$ of M31 with a resolution of approximately 50 arcsec, providing the largest coverage to date based on stellar observations. The derived average extinction, $A_V = 1.17$ mag, agrees well with previous studies. To account for foreground extinction, an extinction map of the Milky Way toward M31 with a resolution of $\sim$ 1.7 arcmin is also constructed, yielding an average extinction of $A_V \approx 0.185$ mag. The results offer a valuable tool for extinction correction in future observations, such as those from the China Space Station Telescope, and provide insights for improving dust models based on the spatial distribution of dust in galaxies like M31. △ Less

Submitted 24 March, 2025; originally announced March 2025.

Spacetime perturbations and quasi-teleparallel gravity

Authors: Jian Gao, Yuxuan Kang, Mingzhe Li, Yeheng Tong

Abstract: Gravity is identical to curved spacetime. It is manifested by the curvature of a Riemannian spacetime in general relativity but by torsion or non-metricity in teleparallel gravity models. In this paper, we apply these multiple options to the spacetime perturbation theory and seek the possibilities of representing the gravitation of the background and that of the perturbation in separate ways. We s… ▽ More Gravity is identical to curved spacetime. It is manifested by the curvature of a Riemannian spacetime in general relativity but by torsion or non-metricity in teleparallel gravity models. In this paper, we apply these multiple options to the spacetime perturbation theory and seek the possibilities of representing the gravitation of the background and that of the perturbation in separate ways. We show that the perturbation around a Riemannian background can be described by torsion or non-metricity, so that we have teleparallel like actions for the perturbation. △ Less

Submitted 16 July, 2025; v1 submitted 4 March, 2025; originally announced March 2025.

Comments: 8 pages, no figure. The version to appear in Chinese Physics C

Report number: USTC-ICTS/PCFT-25-07

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

The Simons Observatory: Science Goals and Forecasts for the Enhanced Large Aperture Telescope

Authors: The Simons Observatory Collaboration, M. Abitbol, I. Abril-Cabezas, S. Adachi, P. Ade, A. E. Adler, P. Agrawal, J. Aguirre, Z. Ahmed, S. Aiola, T. Alford, A. Ali, D. Alonso, M. A. Alvarez, R. An, K. Arnold, P. Ashton, Z. Atkins, J. Austermann, S. Azzoni, C. Baccigalupi, A. Baleato Lizancos, D. Barron, P. Barry, J. Bartlett , et al. (397 additional authors not shown)

Abstract: We describe updated scientific goals for the wide-field, millimeter-wave survey that will be produced by the Simons Observatory (SO). Significant upgrades to the 6-meter SO Large Aperture Telescope (LAT) are expected to be complete by 2028, and will include a doubled mapping speed with 30,000 new detectors and an automated data reduction pipeline. In addition, a new photovoltaic array will supply… ▽ More We describe updated scientific goals for the wide-field, millimeter-wave survey that will be produced by the Simons Observatory (SO). Significant upgrades to the 6-meter SO Large Aperture Telescope (LAT) are expected to be complete by 2028, and will include a doubled mapping speed with 30,000 new detectors and an automated data reduction pipeline. In addition, a new photovoltaic array will supply most of the observatory's power. The LAT survey will cover about 60% of the sky at a regular observing cadence, with five times the angular resolution and ten times the map depth of Planck. The science goals are to: (1) determine the physical conditions in the early universe and constrain the existence of new light particles; (2) measure the integrated distribution of mass, electron pressure, and electron momentum in the late-time universe, and, in combination with optical surveys, determine the neutrino mass and the effects of dark energy via tomographic measurements of the growth of structure at $z < 3$; (3) measure the distribution of electron density and pressure around galaxy groups and clusters, and calibrate the effects of energy input from galaxy formation on the surrounding environment; (4) produce a sample of more than 30,000 galaxy clusters, and more than 100,000 extragalactic millimeter sources, including regularly sampled AGN light-curves, to study these sources and their emission physics; (5) measure the polarized emission from magnetically aligned dust grains in our Galaxy, to study the properties of dust and the role of magnetic fields in star formation; (6) constrain asteroid regoliths, search for Trans-Neptunian Objects, and either detect or eliminate large portions of the phase space in the search for Planet 9; and (7) provide a powerful new window into the transient universe on time scales of minutes to years, concurrent with observations from Rubin of overlapping sky. △ Less

Submitted 7 August, 2025; v1 submitted 1 March, 2025; originally announced March 2025.

Comments: 45 pages, 7 figures; abstract slightly abridged; matches JCAP accepted version. Author contributions to this paper are available at https://simonsobservatory.org/wp-content/uploads/2025/03/Author-contribution-statement-20250228.pdf

New Red Supergiant Stars in the other side of our Galaxy

Authors: Lin Zhang, Bingqiu Chen, Yi Ren, Zehao Zhang, Jian Gao, Biwei Jiang

Abstract: Red supergiant stars (RSGs) are massive stars in a late stage of evolution, crucial for understanding stellar life cycles and Galactic structure. However, RSGs on the far side of our Galaxy have been underexplored due to observational challenges. In this study, we introduce a novel method and present a new catalogue comprising 474 RSGs situated on the far side of the Milky Way, sourced from the OG… ▽ More Red supergiant stars (RSGs) are massive stars in a late stage of evolution, crucial for understanding stellar life cycles and Galactic structure. However, RSGs on the far side of our Galaxy have been underexplored due to observational challenges. In this study, we introduce a novel method and present a new catalogue comprising 474 RSGs situated on the far side of the Milky Way, sourced from the OGLE-III catalogue of Variable Stars (OIII-CVS). The identification of these RSGs was made possible by analyzing the granulation parameters extracted from OGLE I-band time-series data and the stellar parameters from Gaia DR3. Additionally, we estimate the distances to these RSGs using an empirical relation between their characteristic amplitude, absolute magnitude, and intrinsic color, achieving a distance uncertainty of 13%. These newly identified RSGs are distributed at Galactocentric distances between 0 and 30kpc, and reside roughly 1 to 4kpc above and below the Galactic plane. This distribution provides new insights into the structure of the Milky Way, particularly at its outer boundaries. Our results reveal that the vertical distribution of these RSGs is consistent with the flare structure of the Galactic disk, confirming that the far side of the Milky Way exhibits a similar flaring pattern to the near side. This catalogue offers a valuable resource for future detailed studies of RSGs and contributes to a more comprehensive understanding of the Galactic structure and stellar evolution. △ Less

Submitted 17 February, 2025; originally announced February 2025.

Comments: 7 pages, 8 figures

The X-ray Integral Field Unit at the end of the Athena reformulation phase

Authors: Philippe Peille, Didier Barret, Edoardo Cucchetti, Vincent Albouys, Luigi Piro, Aurora Simionescu, Massimo Cappi, Elise Bellouard, Céline Cénac-Morthé, Christophe Daniel, Alice Pradines, Alexis Finoguenov, Richard Kelley, J. Miguel Mas-Hesse, Stéphane Paltani, Gregor Rauw, Agata Rozanska, Jiri Svoboda, Joern Wilms, Marc Audard, Enrico Bozzo, Elisa Costantini, Mauro Dadina, Thomas Dauser, Anne Decourchelle , et al. (257 additional authors not shown)

Abstract: The Athena mission entered a redefinition phase in July 2022, driven by the imperative to reduce the mission cost at completion for the European Space Agency below an acceptable target, while maintaining the flagship nature of its science return. This notably called for a complete redesign of the X-ray Integral Field Unit (X-IFU) cryogenic architecture towards a simpler active cooling chain. Passi… ▽ More The Athena mission entered a redefinition phase in July 2022, driven by the imperative to reduce the mission cost at completion for the European Space Agency below an acceptable target, while maintaining the flagship nature of its science return. This notably called for a complete redesign of the X-ray Integral Field Unit (X-IFU) cryogenic architecture towards a simpler active cooling chain. Passive cooling via successive radiative panels at spacecraft level is now used to provide a 50 K thermal environment to an X-IFU owned cryostat. 4.5 K cooling is achieved via a single remote active cryocooler unit, while a multi-stage Adiabatic Demagnetization Refrigerator ensures heat lift down to the 50 mK required by the detectors. Amidst these changes, the core concept of the readout chain remains robust, employing Transition Edge Sensor microcalorimeters and a SQUID-based Time-Division Multiplexing scheme. Noteworthy is the introduction of a slower pixel. This enables an increase in the multiplexing factor (from 34 to 48) without compromising the instrument energy resolution, hence keeping significant system margins to the new 4 eV resolution requirement. This allows reducing the number of channels by more than a factor two, and thus the resource demands on the system, while keeping a 4' field of view (compared to 5' before). In this article, we will give an overview of this new architecture, before detailing its anticipated performances. Finally, we will present the new X-IFU schedule, with its short term focus on demonstration activities towards a mission adoption in early 2027. △ Less

Submitted 15 February, 2025; originally announced February 2025.

Comments: 44 pages, 14 figures, accepted for publication in Experimental Astronomy

Minute-cadence observations on Galactic plane with Wide Field Survey Telescope (WFST): Overview, methodology and early results

Authors: Jie Lin, Tinggui Wang, Minxuan Cai, Zhen Wan, Xuzhi Li, Lulu Fan, Qingfeng Zhu, Ji-an Jiang, Ning Jiang, Xu Kong, Zheyu Lin, Jiazheng Zhu, Zhengyan Liu, Jie Gao, Bin Li, Feng Li, Ming Liang, Hao Liu, Wei Liu, Wentao Luo, Jinlong Tang, Hairen Wang, Jian Wang, Yongquan Xue, Dazhi Yao , et al. (4 additional authors not shown)

Abstract: As the time-domain survey telescope of the highest survey power in the northern hemisphere currently, Wide Field Survey Telescope (WFST) is scheduled to hourly/daily/semi-weekly scan northern sky up to ~23 mag in four optical (ugri) bands. Unlike the observation cadences in the forthcoming regular survey missions, WFST performed "staring" observations toward Galactic plane in a cadence of… ▽ More As the time-domain survey telescope of the highest survey power in the northern hemisphere currently, Wide Field Survey Telescope (WFST) is scheduled to hourly/daily/semi-weekly scan northern sky up to ~23 mag in four optical (ugri) bands. Unlike the observation cadences in the forthcoming regular survey missions, WFST performed "staring" observations toward Galactic plane in a cadence of $\approx$1 minute for a total on-source time of about 13 hours, during the commissioning and pilot observation phases. Such an observation cadence is well applied in producing densely sampling light curves and hunting for stars exhibiting fast stellar variabilities. Here we introduce the primary methodologies in detecting variability, periodicity, and stellar flares among a half million sources from the minute-cadence observations, and present the WFST g-/r-band light curves generated from periodic variable stars and flaring stars. Benefit from high photometric precisions and deep detection limits of WFST, the observations have captured several rare variable stars, such as a variable hot white dwarf (WD) and an ellipsoidal WD binary candidate. By surveying the almost unexplored parameter spaces for variables, WFST will lead to new opportunities in discovering unique variable stars in the northern sky. △ Less

Submitted 16 March, 2025; v1 submitted 17 December, 2024; originally announced December 2024.

Comments: 20 pages, 12 figures, accepted by ApJS

A Novel Density Profile for Isothermal Cores of Dark Matter Halos

Authors: Vinh Tran, Xuejian Shen, Mark Vogelsberger, Daniel Gilman, Stephanie O'Neil, Cian Roche, Oliver Zier, Jiarun Gao

Abstract: We present a novel analytic density profile for halos in self-interacting dark matter (SIDM) models, which accurately captures the isothermal-core configuration, i.e. where both the density and velocity dispersion profiles exhibit central plateaus in the halo innermost region. Importantly, the profile retains a simple and tractable functional form. We demonstrate analytically how our density profi… ▽ More We present a novel analytic density profile for halos in self-interacting dark matter (SIDM) models, which accurately captures the isothermal-core configuration, i.e. where both the density and velocity dispersion profiles exhibit central plateaus in the halo innermost region. Importantly, the profile retains a simple and tractable functional form. We demonstrate analytically how our density profile satisfies the aforementioned conditions, with comparisons to other contemporary functional choices. We further validate the profile using idealized N-body simulations, showing that it provides excellent representations of both the density and velocity dispersion profiles across a broad range of evolutionary stages, from the early thermalization phase to the late core-collapse regime. As a result of its accuracy and simplicity, the proposed profile offers a robust framework for analyzing halo evolution in a variety of SIDM scenarios. It also holds practical utility in reducing simulation needs and in generating initial conditions for simulations targeting the deep core-collapse regime. △ Less

Submitted 18 November, 2025; v1 submitted 18 November, 2024; originally announced November 2024.

Comments: 9 pages, 5 figures, 1 table, submitted to PRD, referee response 2

Gravitational Wave Astronomy With TianQin

Authors: En-Kun Li, Shuai Liu, Alejandro Torres-Orjuela, Xian Chen, Kohei Inayoshi, Long Wang, Yi-Ming Hu, Pau Amaro-Seoane, Abbas Askar, Cosimo Bambi, Pedro R. Capelo, Hong-Yu Chen, Alvin J. K. Chua, Enrique Condés-Breña, Lixin Dai, Debtroy Das, Andrea Derdzinski, Hui-Min Fan, Michiko Fujii, Jie Gao, Mudit Garg, Hongwei Ge, Mirek Giersz, Shun-Jia Huang, Arkadiusz Hypki , et al. (28 additional authors not shown)

Abstract: The opening of the gravitational wave window has significantly enhanced our capacity to explore the universe's most extreme and dynamic sector. In the mHz frequency range, a diverse range of compact objects, from the most massive black holes at the farthest reaches of the Universe to the lightest white dwarfs in our cosmic backyard, generate a complex and dynamic symphony of gravitational wave sig… ▽ More The opening of the gravitational wave window has significantly enhanced our capacity to explore the universe's most extreme and dynamic sector. In the mHz frequency range, a diverse range of compact objects, from the most massive black holes at the farthest reaches of the Universe to the lightest white dwarfs in our cosmic backyard, generate a complex and dynamic symphony of gravitational wave signals. Once recorded by gravitational wave detectors, these unique fingerprints have the potential to decipher the birth and growth of cosmic structures over a wide range of scales, from stellar binaries and stellar clusters to galaxies and large-scale structures. The TianQin space-borne gravitational wave mission is scheduled for launch in the 2030s, with an operational lifespan of five years. It will facilitate pivotal insights into the history of our universe. This document presents a concise overview of the detectable sources of TianQin, outlining their characteristics, the challenges they present, and the expected impact of the TianQin observatory on our understanding of them. △ Less

Submitted 2 December, 2024; v1 submitted 29 September, 2024; originally announced September 2024.

Comments: TianQin Gravitational Wave Whitepaper, 72 pages, 30 figures

GRB 240529A: A Tale of Two Shocks

Authors: Tian-Rui Sun, Jin-Jun Geng, Jing-Zhi Yan, You-Dong Hu, Xue-Feng Wu, Alberto J. Castro-Tirado, Chao Yang, Yi-Ding Ping, Chen-Ran Hu, Fan Xu, Hao-Xuan Gao, Ji-An Jiang, Yan-Tian Zhu, Yongquan Xue, Ignacio Pérez-García, Si-Yu Wu, Emilio Fernández-García, María D. Caballero-García, Rubén Sánchez-Ramírez, Sergiy Guziy, Ignacio Olivares, Carlos Jesus Pérez del Pulgar, A. Castellón, Sebastián Castillo, Ding-Rong Xiong , et al. (44 additional authors not shown)

Abstract: Thanks to the rapidly increasing time-domain facilities, we are entering a golden era of research on gamma-ray bursts (GRBs). In this Letter, we report our observations of GRB 240529A with the Burst Optical Observer and Transient Exploring System, the 1.5-meter telescope at Observatorio Sierra Nevada, the 2.5-meter Wide Field Survey Telescope of China, the Large Binocular Telescope, and the Telesc… ▽ More Thanks to the rapidly increasing time-domain facilities, we are entering a golden era of research on gamma-ray bursts (GRBs). In this Letter, we report our observations of GRB 240529A with the Burst Optical Observer and Transient Exploring System, the 1.5-meter telescope at Observatorio Sierra Nevada, the 2.5-meter Wide Field Survey Telescope of China, the Large Binocular Telescope, and the Telescopio Nazionale Galileo. The prompt emission of GRB 240529A shows two comparable energetic episodes separated by a quiescence time of roughly 400 s. Combining all available data on the GRB Coordinates Network, we reveal the simultaneous apparent X-ray plateau and optical re-brightening around $10^3-10^4$ s after the burst. Rather than the energy injection from the magnetar as widely invoked for similar GRBs, the multi-wavelength emissions could be better explained as two shocks launched from the central engine separately. The optical peak time and our numerical modeling suggest that the initial bulk Lorentz factor of the later shock is roughly 50, which indicates that the later jet should be accretion-driven and have a higher mass loading than a typical one. The quiescence time between the two prompt emission episodes may be caused by the transition between different accretion states of a central magnetar or black hole, or the fall-back accretion process. A sample of similar bursts with multiple emission episodes in the prompt phase and sufficient follow-up could help to probe the underlying physics of GRB central engines. △ Less

Submitted 26 September, 2024; originally announced September 2024.

Comments: Resubmitted to ApJL after addressing the referee's comments; comments are welcome

Mass-loss Rate of Highly Evolved Stars in the Magellanic Clouds

Authors: Jing Wen, Ming Yang, Jian Gao, Bingqiu Chen, Yi Ren, Biwei Jiang

Abstract: Asymptotic giant branch stars (AGBs) and red supergiant stars (RSGs) exhibit significant mass loss phenomena and are considered important sources of interstellar dust. In this work, we employed an uniform method of spectral energy distribution fitting to analyze a large, and hence statistically significant, sample of approximately 40,000 RSGs and AGBs in the Magellanic Clouds (MCs), providing a ne… ▽ More Asymptotic giant branch stars (AGBs) and red supergiant stars (RSGs) exhibit significant mass loss phenomena and are considered important sources of interstellar dust. In this work, we employed an uniform method of spectral energy distribution fitting to analyze a large, and hence statistically significant, sample of approximately 40,000 RSGs and AGBs in the Magellanic Clouds (MCs), providing a new catalog of evolved stars that includes stellar parameters and dust properties. Our results reveal that the total dust-production rate (DPR) of the Large Magellanic Cloud is approximately $9.69\times10^{-6}\,\rm{M_{\odot }\, yr^{-1}}$, while it is around $1.75\times10^{-6}\,\rm{M_{\odot }\,yr^{-1}}$ for the Small Magellanic Cloud, with a few stars significantly contributing to the total DPR. No significant differences were observed in the contributions to DPR from carbon-rich and oxygen-rich (O-rich) evolved stars in the MCs. We explored the relations between stellar parameters (luminosity, infrared color, period, amplitude) and mass-loss rate (MLR) for evolved stars. A prominent turning point at $\log{(L/L_{\odot})} \approx 4.4$ appears in the luminosity-MLR diagram of RSGs, potentially related to the mass-loss mechanism of RSGs. The luminosity-MLR relation of AGBs is highly scattered. The DPR of AGBs shows a clear change with pulsation period and amplitude, with DPR exhibiting a drastic increase at pulsation periods of approximately 300 days and I-band amplitudes greater than 0.5 mag. Metallicity has some impact on the DPR of O-rich stars, with lower metallicity seeming to result in lower mean DPR and a higher proportion of optically thin stars. △ Less

Submitted 15 September, 2024; originally announced September 2024.

Comments: 30 pages,19 figures. Accepted for publication in ApJS

System performance of a cryogenic test-bed for the time-division multiplexing readout for NewAthena X-IFU

Authors: Davide Vaccaro, Jan van der Kuur, Paul van der Hulst, Tobias Vos, Martin de Wit, Luciano Gottardi, Kevin Ravensberg, Emanuele Taralli, Joseph Adams, Simon Bandler, Douglas Bennet, James Chervenak, Bertrand Doriese, Malcolm Durkin, Johnathon Gard, Carl Reintsema, Kazuhiro Sakai, Steven Smith, Joel Ullom, Nicholas Wakeham, Jan-Willem den Herder, Brian jackson, Pourya Khosropanah, Jian-Rong Gao, Peter Roelfsema , et al. (1 additional authors not shown)

Abstract: The X-ray Integral Field Unit (X-IFU) is an instrument of ESA's future NewAthena space observatory, with the goal to provide high-energy resolution ($<$ 4 eV at X-ray energies up to 7 keV) and high-spatial resolution (9") spectroscopic imaging over the X-ray energy range from 200 eV to 12 keV, by means of an array of about 1500 transition-edge sensors (TES) read out via SQUID time-division multipl… ▽ More The X-ray Integral Field Unit (X-IFU) is an instrument of ESA's future NewAthena space observatory, with the goal to provide high-energy resolution ($<$ 4 eV at X-ray energies up to 7 keV) and high-spatial resolution (9") spectroscopic imaging over the X-ray energy range from 200 eV to 12 keV, by means of an array of about 1500 transition-edge sensors (TES) read out via SQUID time-division multiplexing (TDM). A TDM-based laboratory test-bed has been assembled at SRON, hosting an array of $75\times 75\ \upmu$m$^2$ TESs that are read out via 2-column $\times$ 32-row TDM. A system component that is critical to high-performance operation is the wiring harness that connects the room-temperature electronics to the cryogenic readout componentry. We report here on our characterization of such a test-bed, whose harness has a length close to what envisioned for X-IFU, which allowed to achieve a co-added energy resolution at a level of 2.7~eV FWHM at 6~keV via 32-row readout. In addition, we provide an outlook on the integration of TDM readout into the X-IFU Focal-Plane Assembly Development Model. △ Less

Submitted 5 November, 2024; v1 submitted 9 September, 2024; originally announced September 2024.

Comments: Submitted for publication to Journal of Astronomical Telescopes, Instrumentation and Systems. arXiv admin note: text overlap with arXiv:2403.02978

Journal ref: Journal of Astronomical Telescopes, Instruments, and Systems, Vol. 10, Issue 4, 046002 (December 2024)

Detection of gamma-ray burst Amati relation based on Hubble data set and Pantheon+ samples

Authors: Yufen Han, Jiaze Gao, Gang Liu, Lixin Xu

Abstract: Using gamma-ray bursts as standard candles for cosmological parameter constraints rely on their empirical luminosity relations and low-redshift calibration. In this paper, we examine the Amati relation and its potential corrections based on the A118 sample of higher-quality gamma-ray bursts, using both Hubble data set and Pantheon+ samples as calibration samples in the redshift range of z < 1.965.… ▽ More Using gamma-ray bursts as standard candles for cosmological parameter constraints rely on their empirical luminosity relations and low-redshift calibration. In this paper, we examine the Amati relation and its potential corrections based on the A118 sample of higher-quality gamma-ray bursts, using both Hubble data set and Pantheon+ samples as calibration samples in the redshift range of z < 1.965. In calibrating gamma-ray bursts using these two datasets, we employ Gaussian processes to obtain corresponding Hubble diagrams to avoid the dependence on cosmological models in the calibration process. We first divided the low-redshift sample of GRBs into two bins and examined the Amati relation and its potential modifications. We found that under both calibrations, the Amati relation did not show evidence of redshift evolution (68% confidence level). For the other two Amati relations that include redshift evolution terms, the central values of the redshift evolution coefficients deviated from 0, but due to the limitations of the sample size and the increase in the number of parameters, most of the redshift evolution coefficients were not able to be excluded from 0 at the 1 sigma level. Therefore, to assess their situation across the entire redshift range, we employed MCMC to globally fit three types of Amati relations. By computing AIC and BIC, we found that for the GRB A118 sample, the standard Amati relation remains the most fitting empirical luminosity formula, and no potential redshift evolution trend was observed for two different low-redshift calibrating sources. △ Less

Submitted 3 September, 2024; v1 submitted 24 August, 2024; originally announced August 2024.

Redshift Evolution of the HII Galaxy $L$-$σ$ Relation: Gaussian Process Analysis and Cosmological Implications

Authors: Jiaze Gao, Yun Chen, Lixin Xu

Abstract: The utility of HII starburst galaxies (HIIGs) as cosmic standard candles relies on the empirical $L$-$σ$ relation between the H$β$ luminosity ($L$) and ionized gas velocity dispersion ($σ$). However, the classic scaling $L$-$σ$ relation well-calibrated with the low-redshift HIIGs fails to properly describe their high-redshift counterparts. To address this, we try to explore new parameterization of… ▽ More The utility of HII starburst galaxies (HIIGs) as cosmic standard candles relies on the empirical $L$-$σ$ relation between the H$β$ luminosity ($L$) and ionized gas velocity dispersion ($σ$). However, the classic scaling $L$-$σ$ relation well-calibrated with the low-redshift HIIGs fails to properly describe their high-redshift counterparts. To address this, we try to explore new parameterization of the $L$-$σ$ relation, which is expected to be valid across all redshifts. Using Gaussian process reconstruction of the Hubble diagram from the Pantheon+ supernovae Ia sample, we compare three modified versions of the $L$-$σ$ relation against the classic scaling form through Bayesian evidence analysis. Our results identify the logarithmic redshift-dependent correction as the most statistically favored parameterization. This conclusion remains valid when repeating the analysis in the $Λ$CDM model with cosmological parameters fixed to their Planck 2018 fiducial values, which demonstrates the robustness of our results across different cosmological distance estimation approaches. After accounting for Malmquist bias effects, we still detect redshift evolution in the $L-σ$ relation, albeit with reduced statistical significance. Furthermore, we perform cosmological analysis within the $Λ$CDM model from a joint sample of HIIGs and giant extragalactic HII regions (GEHRs), and yield constraints on $H_0$ and $Ω_m$ that are approximately one order of magnitude less precise than Planck 2018 results. △ Less

Submitted 2 August, 2025; v1 submitted 20 August, 2024; originally announced August 2024.

Comments: 8 pages, 2 table, 3 figures. The models and figures are updated

Characterizing the current systems in the Martian ionosphere

Authors: Jiawei Gao, Shibang Li, Anna Mittelholz, Zhaojin Rong, Moa Persson, Zhen Shi, Haoyu Lu, Chi Zhang, Xiaodong Wang, Chuanfei Dong, Lucy Klinger, Jun Cui, Yong Wei, Yongxin Pan

Abstract: When the solar wind interacts with the ionosphere of an unmagnetized planet, it induces currents that form an induced magnetosphere. These currents and their associated magnetic fields play a pivotal role in controlling the movement of charged particles, which is essential for understanding the escape of planetary ions. Unlike the well-documented magnetospheric current systems, the ionospheric cur… ▽ More When the solar wind interacts with the ionosphere of an unmagnetized planet, it induces currents that form an induced magnetosphere. These currents and their associated magnetic fields play a pivotal role in controlling the movement of charged particles, which is essential for understanding the escape of planetary ions. Unlike the well-documented magnetospheric current systems, the ionospheric current systems on unmagnetized planets remain less understood, which constrains the quantification of electrodynamic energy transfer from stars to these planets. Here, utilizing eight years of data from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we investigate the global distribution of ionospheric currents on Mars. We have identified two distinct current systems in the ionosphere: one aligns with the solar wind electric field yet exhibits hemispheric asymmetry perpendicular to the electric field direction; the other corresponds to the flow pattern of annually-averaged neutral winds. We propose that these two current systems are driven by the solar wind and atmospheric neutral winds, respectively. Our findings reveal that Martian ionospheric dynamics are influenced by the neutral winds from below and the solar wind from above, highlighting the complex and intriguing nature of current systems on unmagnetized planets. △ Less

Submitted 6 August, 2024; originally announced August 2024.

Comments: 20 pages, 6 figures

Main-sequence systems: orbital stability around single star hosts

Authors: Hareesh Gautham Bhaskar, Nathaniel W. H. Moore, Jiapeng Gao, Gongjie Li, Billy Quarles

Abstract: Stability is one of the most fundamental aspects regarding planetary systems. It plays an important role in our understanding on the formation channel of the planetary systems, as well as their habitability. Many approaches have been adopted to determine the stability of these systems, including brute-force N-body simulations, semi-analytical calculations, and more recently machine learning method… ▽ More Stability is one of the most fundamental aspects regarding planetary systems. It plays an important role in our understanding on the formation channel of the planetary systems, as well as their habitability. Many approaches have been adopted to determine the stability of these systems, including brute-force N-body simulations, semi-analytical calculations, and more recently machine learning methods. This allows significant advances in our understanding of planetary system dynamics, as well as providing tools to constrain unknown parameters of exoplanetary systems (assuming these systems are stable). In the following, we focus on planets around single star hosts, and we provide an overview of the studies of planetary system stability for compact multi-planet systems and hierarchical multi-planet systems. △ Less

Submitted 18 July, 2024; originally announced July 2024.

Comments: Preprint of a chapter for the 'Encyclopedia of Astrophysics' (Editor-in-Chief Ilya Mandel, Section Editor Dimitri Veras) to be published by Elsevier as a Reference Module. The number of references was capped

Novae: An Important Source of Lithium in the Galaxy

Authors: Jun Gao, Chunhua Zhu, Guoliang Lü, Jinlong Yu, Lin Li, Helei Liu, Sufen Guo

Abstract: The source of the Galactic Lithium (Li) has long been a puzzle. With the discovery of Li in novae, extensive research has been conducted. However, there still exists a significant disparity between the observed abundance of lithium in novae and the existing theoretical predictions. Using the Modules for Experiments in Stellar Astrophysics (MESA), we simulate the evolution of nova with element diff… ▽ More The source of the Galactic Lithium (Li) has long been a puzzle. With the discovery of Li in novae, extensive research has been conducted. However, there still exists a significant disparity between the observed abundance of lithium in novae and the existing theoretical predictions. Using the Modules for Experiments in Stellar Astrophysics (MESA), we simulate the evolution of nova with element diffusion and appropriately increased the amount of 3^He in the mixtures. Element diffusion enhances the transport efficiency between the nuclear reaction zone and the convective region on the surface of the white dwarf during nova eruptions, which results in more 7^Be to be transmitted to the white dwarf surface and ultimately ejected. Compared to the previous predictions, the abundance of 7^Be in novae simulated in our model significantly increases. And the result is able to explain almost all observed novae. Using the method of population synthesis, we calculate Li yield in the Galaxy. We find that the Galactic occurrence rate of nova is about 130 yr^{-1}, and about 110M Li produced by nova eruption is ejected into the interstellar medium (ISM). About 73\% of Li in the Galactic ISM originates from novae, and approximately 15\%-20\% of the entire Galaxy. It means that novae are the important source of Li in the Galactic. △ Less

Submitted 20 June, 2024; originally announced June 2024.

Comments: 12 pages, 4 figures. Accepted for publication in Astrophysical Journal

CCAT: Comparisons of 280 GHz TiN and Al Kinetic Inductance Detector Arrays

Authors: Cody J. Duell, Jason Austermann, James Beall, James R. Burgoyne, Scott C. Chapman, Steve K. Choi, Rodrigo G. Freundt, Jiansong Gao, Christopher Groppi, Anthony I. Huber, Zachary B. Huber, Johannes Hubmayr, Ben Keller, Yaqiong Li, Lawrence T. Lin, Justin Matthewson, Philip Mauskopf, Alicia Middleton, Colin C. Murphy, Michael D. Niemack, Thomas Nikola, Adrian K. Sinclair, Ema Smith, Jeff van Lanen, Anna Vaskuri , et al. (5 additional authors not shown)

Abstract: The CCAT Collaboration's six-meter Fred Young Submillimeter Telescope is scheduled to begin observing in the Chilean Atacama in 2025, targeting a variety of science goals throughout cosmic history. Prime-Cam is a 1.8-meter diameter cryostat that will host up to seven independent instrument modules designed for simultaneous spectroscopic and broadband, polarimetric surveys at millimeter to submilli… ▽ More The CCAT Collaboration's six-meter Fred Young Submillimeter Telescope is scheduled to begin observing in the Chilean Atacama in 2025, targeting a variety of science goals throughout cosmic history. Prime-Cam is a 1.8-meter diameter cryostat that will host up to seven independent instrument modules designed for simultaneous spectroscopic and broadband, polarimetric surveys at millimeter to submillimeter wavelengths. The first of these instrument modules, the 280 GHz module, will include ${\sim}$10,000 kinetic inductance detectors (KIDs) across three arrays. While the first array was fabricated out of tri-layer TiN/Ti/TiN, the other two arrays were fabricated out of a single layer of Al. This combination of materials within the same instrument provides a unique opportunity to directly compare the performance and noise properties of two different detector materials that are seeing increasing use within the field. We present preliminary comparisons here based on lab testing, along with a discussion of the potential impacts on operation when observing and translating raw data to science-grade maps. △ Less

Submitted 10 June, 2024; originally announced June 2024.

Comments: 6 pages, 3 figures, conference proceedings submitted to the Journal of Low Temperature Physics

Probing the distinct extinction law of the Pillars of Creation in M16 with JWST

Authors: Jun Li, Bingqiu Chen, Biwei Jiang, Jian Gao, Xi Chen

Abstract: Investigating the extinction law in regions of high dust extinction, such as the Pillars of Creation within the M16 region, is crucial for understanding the densest parts of the interstellar medium (ISM). In this study, we utilize observations from the Near-Infrared Camera (NIRCam) and the Mid-Infrared Instrument (MIRI) onboard the James Webb Space Telescope (JWST) to analyze the color-excess rati… ▽ More Investigating the extinction law in regions of high dust extinction, such as the Pillars of Creation within the M16 region, is crucial for understanding the densest parts of the interstellar medium (ISM). In this study, we utilize observations from the Near-Infrared Camera (NIRCam) and the Mid-Infrared Instrument (MIRI) onboard the James Webb Space Telescope (JWST) to analyze the color-excess ratios $E(F090W-λ)/E(F090W-F200W)$ across a wavelength range of $0.9-7.7\,μ\mathrm{m}$. Our method involves performing linear regression on color-color diagrams to derive these ratios. The enhanced detection capabilities of JWST data allow us to probe the distinct extinction law to the densest regions in M16 corresponding to an extinction depth up to $A_V \sim 60$\,mag. Remarkably, the resultant color-excess ratio curve exhibits a flatter profile than predicted by typical dust extinction models with $R_V = 5.5$ for dense ISM environments. Moreover, we observe that the mid-infrared (MIR) extinction law diverges from the near-infrared (NIR) power-law, showing a tendency for the slope to flatten as the wavelength increases. These findings have significant implications for our understanding of the dust properties in dense interstellar environments. △ Less

Submitted 5 June, 2024; originally announced June 2024.

Comments: Accepted for publication in The Astrophysical Journal Letters (9 pages, 4 figures, 2 tables)

Single Aperture Large Telescope for Universe Studies (SALTUS): Science Overview

Authors: Gordon Chin, Carrie M. Anderson, Jennifer Bergner, Nicolas Biver, Gordon L. Bjoraker, Thibault Cavalie, Michael DiSanti, Jian-Rong Gao, Paul Hartogh, Leon K. Harding, Qing Hu, Daewook Kim, Craig Kulesa, Gert de Lange, David T. Leisawitz, Rebecca C. Levy, Arthur Lichtenberger, Daniel P. Marronh, Joan Najita, Trent Newswander, George H. Rieke, Dimitra Rigopoulou, Peter Roefsema, Nathan X. Roth, Kamber Schwarz , et al. (11 additional authors not shown)

Abstract: The SALTUS Probe mission will provide a powerful far-infrared (far-IR) pointed space observatory to explore our cosmic origins and the possibility of life elsewhere. The observatory employs an innovative deployable 14-m aperture, with a sunshield that will radiatively cool the off-axis primary to <45K. This cooled primary reflector works in tandem with cryogenic coherent and incoherent instruments… ▽ More The SALTUS Probe mission will provide a powerful far-infrared (far-IR) pointed space observatory to explore our cosmic origins and the possibility of life elsewhere. The observatory employs an innovative deployable 14-m aperture, with a sunshield that will radiatively cool the off-axis primary to <45K. This cooled primary reflector works in tandem with cryogenic coherent and incoherent instruments that span the 34 to 660 micron far-IR range at both high and moderate spectral resolutions. △ Less

Submitted 21 May, 2024; originally announced May 2024.

Comments: 49 pages, 10 figures, 3 tables, submitted to SPIE JATIS

Combined Pre-Supernova Alert System with Kamland and Super-Kamiokande

Authors: KamLAND, Super-Kamiokande Collaborations, :, Seisho Abe, Minori Eizuka, Sawako Futagi, Azusa Gando, Yoshihito Gando, Shun Goto, Takahiko Hachiya, Kazumi Hata, Koichi Ichimura, Sei Ieki, Haruo Ikeda, Kunio Inoue, Koji Ishidoshiro, Yuto Kamei, Nanami Kawada, Yasuhiro Kishimoto, Masayuki Koga, Maho Kurasawa, Tadao Mitsui, Haruhiko Miyake, Daisuke Morita, Takeshi Nakahata , et al. (290 additional authors not shown)

Abstract: Preceding a core-collapse supernova, various processes produce an increasing amount of neutrinos of all flavors characterized by mounting energies from the interior of massive stars. Among them, the electron antineutrinos are potentially detectable by terrestrial neutrino experiments such as KamLAND and Super-Kamiokande via inverse beta decay interactions. Once these pre-supernova neutrinos are ob… ▽ More Preceding a core-collapse supernova, various processes produce an increasing amount of neutrinos of all flavors characterized by mounting energies from the interior of massive stars. Among them, the electron antineutrinos are potentially detectable by terrestrial neutrino experiments such as KamLAND and Super-Kamiokande via inverse beta decay interactions. Once these pre-supernova neutrinos are observed, an early warning of the upcoming core-collapse supernova can be provided. In light of this, KamLAND and Super-Kamiokande, both located in the Kamioka mine in Japan, have been monitoring pre-supernova neutrinos since 2015 and 2021, respectively. Recently, we performed a joint study between KamLAND and Super-Kamiokande on pre-supernova neutrino detection. A pre-supernova alert system combining the KamLAND detector and the Super-Kamiokande detector was developed and put into operation, which can provide a supernova alert to the astrophysics community. Fully leveraging the complementary properties of these two detectors, the combined alert is expected to resolve a pre-supernova neutrino signal from a 15 M$_{\odot}$ star within 510 pc of the Earth, at a significance level corresponding to a false alarm rate of no more than 1 per century. For a Betelgeuse-like model with optimistic parameters, it can provide early warnings up to 12 hours in advance. △ Less

Submitted 1 July, 2024; v1 submitted 15 April, 2024; originally announced April 2024.

Comments: Resubmitted to ApJ. 22 pages, 16 figures, for more information about the combined pre-supernova alert system, see https://www.lowbg.org/presnalarm/

Development of a data overflow protection system for Super-Kamiokande to maximize data from nearby supernovae

Authors: M. Mori, K. Abe, Y. Hayato, K. Hiraide, K. Hosokawa, K. Ieki, M. Ikeda, J. Kameda, Y. Kanemura, R. Kaneshima, Y. Kashiwagi, Y. Kataoka, S. Miki, S. Mine, M. Miura, S. Moriyama, Y. Nakano, M. Nakahata, S. Nakayama, Y. Noguchi, K. Okamoto, K. Sato, H. Sekiya, H. Shiba, K. Shimizu , et al. (230 additional authors not shown)

Abstract: Neutrinos from very nearby supernovae, such as Betelgeuse, are expected to generate more than ten million events over 10\,s in Super-Kamokande (SK). At such large event rates, the buffers of the SK analog-to-digital conversion board (QBEE) will overflow, causing random loss of data that is critical for understanding the dynamics of the supernova explosion mechanism. In order to solve this problem,… ▽ More Neutrinos from very nearby supernovae, such as Betelgeuse, are expected to generate more than ten million events over 10\,s in Super-Kamokande (SK). At such large event rates, the buffers of the SK analog-to-digital conversion board (QBEE) will overflow, causing random loss of data that is critical for understanding the dynamics of the supernova explosion mechanism. In order to solve this problem, two new DAQ modules were developed to aid in the observation of very nearby supernovae. The first of these, the SN module, is designed to save only the number of hit PMTs during a supernova burst and the second, the Veto module, prescales the high rate neutrino events to prevent the QBEE from overflowing based on information from the SN module. In the event of a very nearby supernova, these modules allow SK to reconstruct the time evolution of the neutrino event rate from beginning to end using both QBEE and SN module data. This paper presents the development and testing of these modules together with an analysis of supernova-like data generated with a flashing laser diode. We demonstrate that the Veto module successfully prevents DAQ overflows for Betelgeuse-like supernovae as well as the long-term stability of the new modules. During normal running the Veto module is found to issue DAQ vetos a few times per month resulting in a total dead time less than 1\,ms, and does not influence ordinary operations. Additionally, using simulation data we find that supernovae closer than 800~pc will trigger Veto module resulting in a prescaling of the observed neutrino data. △ Less

Submitted 13 August, 2024; v1 submitted 12 April, 2024; originally announced April 2024.

Comments: 28 pages, 18 figures. Submitted to PTEP

Measurements of the charge ratio and polarization of cosmic-ray muons with the Super-Kamiokande detector

Authors: H. Kitagawa, T. Tada, K. Abe, C. Bronner, Y. Hayato, K. Hiraide, K. Hosokawa, K. Ieki, M. Ikeda, J. Kameda, Y. Kanemura, R. Kaneshima, Y. Kashiwagi, Y. Kataoka, S. Miki, S. Mine, M. Miura, S. Moriyama, Y. Nakano, M. Nakahata, S. Nakayama, Y. Noguchi, K. Okamoto, K. Sato, H. Sekiya , et al. (231 additional authors not shown)

Abstract: We present the results of the charge ratio ($R$) and polarization ($P^μ_{0}$) measurements using the decay electron events collected from 2008 September to 2022 June by the Super-Kamiokande detector. Because of its underground location and long operation, we performed high precision measurements by accumulating cosmic-ray muons. We measured the muon charge ratio to be $R=1.32 \pm 0.02$… ▽ More We present the results of the charge ratio ($R$) and polarization ($P^μ_{0}$) measurements using the decay electron events collected from 2008 September to 2022 June by the Super-Kamiokande detector. Because of its underground location and long operation, we performed high precision measurements by accumulating cosmic-ray muons. We measured the muon charge ratio to be $R=1.32 \pm 0.02$ $(\mathrm{stat.}{+}\mathrm{syst.})$ at $E_μ\cos θ_{\mathrm{Zenith}}=0.7^{+0.3}_{-0.2}$ $\mathrm{TeV}$, where $E_μ$ is the muon energy and $θ_{\mathrm{Zenith}}$ is the zenith angle of incoming cosmic-ray muons. This result is consistent with the Honda flux model while this suggests a tension with the $πK$ model of $1.9σ$. We also measured the muon polarization at the production location to be $P^μ_{0}=0.52 \pm 0.02$ $(\mathrm{stat.}{+}\mathrm{syst.})$ at the muon momentum of $0.9^{+0.6}_{-0.1}$ $\mathrm{TeV}/c$ at the surface of the mountain; this also suggests a tension with the Honda flux model of $1.5σ$. This is the most precise measurement ever to experimentally determine the cosmic-ray muon polarization near $1~\mathrm{TeV}/c$. These measurement results are useful to improve the atmospheric neutrino simulations. △ Less

Submitted 4 November, 2024; v1 submitted 13 March, 2024; originally announced March 2024.

Comments: 29 pages, 45 figures

Journal ref: Phys. Rev. D 110, 082008 (2024)

Second gadolinium loading to Super-Kamiokande

Authors: K. Abe, C. Bronner, Y. Hayato, K. Hiraide, K. Hosokawa, K. Ieki, M. Ikeda, J. Kameda, Y. Kanemura, R. Kaneshima, Y. Kashiwagi, Y. Kataoka, S. Miki, S. Mine, M. Miura, S. Moriyama, Y. Nakano, M. Nakahata, S. Nakayama, Y. Noguchi, K. Sato, H. Sekiya, H. Shiba, K. Shimizu, M. Shiozawa , et al. (225 additional authors not shown)

Abstract: The first loading of gadolinium (Gd) into Super-Kamiokande in 2020 was successful, and the neutron capture efficiency on Gd reached 50\%. To further increase the Gd neutron capture efficiency to 75\%, 26.1 tons of $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ was additionally loaded into Super-Kamiokande (SK) from May 31 to July 4, 2022. As the amount of loaded $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ was do… ▽ More The first loading of gadolinium (Gd) into Super-Kamiokande in 2020 was successful, and the neutron capture efficiency on Gd reached 50\%. To further increase the Gd neutron capture efficiency to 75\%, 26.1 tons of $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ was additionally loaded into Super-Kamiokande (SK) from May 31 to July 4, 2022. As the amount of loaded $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ was doubled compared to the first loading, the capacity of the powder dissolving system was doubled. We also developed new batches of gadolinium sulfate with even further reduced radioactive impurities. In addition, a more efficient screening method was devised and implemented to evaluate these new batches of $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$. Following the second loading, the Gd concentration in SK was measured to be $333.5\pm2.5$ ppm via an Atomic Absorption Spectrometer (AAS). From the mean neutron capture time constant of neutrons from an Am/Be calibration source, the Gd concentration was independently measured to be 332.7 $\pm$ 6.8(sys.) $\pm$ 1.1(stat.) ppm, consistent with the AAS result. Furthermore, during the loading the Gd concentration was monitored continually using the capture time constant of each spallation neutron produced by cosmic-ray muons,and the final neutron capture efficiency was shown to become 1.5 times higher than that of the first loaded phase, as expected. △ Less

Submitted 18 June, 2024; v1 submitted 12 March, 2024; originally announced March 2024.

Comments: 34 pages, 13 figures, submitted to Nuclear Inst. and Methods in Physics Research, A

Journal ref: Nuclear Inst. and Methods in Physics Research, A 1065 (2024) 169480

Performance of SK-Gd's Upgraded Real-time Supernova Monitoring System

Authors: Y. Kashiwagi, K. Abe, C. Bronner, Y. Hayato, K. Hiraide, K. Hosokawa, K. Ieki, M. Ikeda, J. Kameda, Y. Kanemura, R. Kaneshima, Y. Kataoka, S. Miki, S. Mine, M. Miura, S. Moriyama, Y. Nakano, M. Nakahata, S. Nakayama, Y. Noguchi, K. Sato, H. Sekiya, H. Shiba, K. Shimizu, M. Shiozawa , et al. (214 additional authors not shown)

Abstract: Among multi-messenger observations of the next galactic core-collapse supernova, Super-Kamiokande (SK) plays a critical role in detecting the emitted supernova neutrinos, determining the direction to the supernova (SN), and notifying the astronomical community of these observations in advance of the optical signal. On 2022, SK has increased the gadolinium dissolved in its water target (SK-Gd) and… ▽ More Among multi-messenger observations of the next galactic core-collapse supernova, Super-Kamiokande (SK) plays a critical role in detecting the emitted supernova neutrinos, determining the direction to the supernova (SN), and notifying the astronomical community of these observations in advance of the optical signal. On 2022, SK has increased the gadolinium dissolved in its water target (SK-Gd) and has achieved a Gd concentration of 0.033%, resulting in enhanced neutron detection capability, which in turn enables more accurate determination of the supernova direction. Accordingly, SK-Gd's real-time supernova monitoring system (Abe te al. 2016b) has been upgraded. SK_SN Notice, a warning system that works together with this monitoring system, was released on December 13, 2021, and is available through GCN Notices (Barthelmy et al. 2000). When the monitoring system detects an SN-like burst of events, SK_SN Notice will automatically distribute an alarm with the reconstructed direction to the supernova candidate within a few minutes. In this paper, we present a systematic study of SK-Gd's response to a simulated galactic SN. Assuming a supernova situated at 10 kpc, neutrino fluxes from six supernova models are used to characterize SK-Gd's pointing accuracy using the same tools as the online monitoring system. The pointing accuracy is found to vary from 3-7$^\circ$ depending on the models. However, if the supernova is closer than 10 kpc, SK_SN Notice can issue an alarm with three-degree accuracy, which will benefit follow-up observations by optical telescopes with large fields of view. △ Less

Submitted 13 March, 2024; v1 submitted 11 March, 2024; originally announced March 2024.

Comments: 38 pages, 29 figures, 6 tables

Developments on frequency domain multiplexing readout for large arrays of transition-edge sensor X-ray micro-calorimeters

Authors: D. Vaccaro, H. Akamatsu, L. Gottardi, M. de Wit, M. P. Bruijn, J. van der Kuur, K. Nagayoshi, E. Taralli, K. Ravensberg, J. R. Gao, J. W. A. den Herder

Abstract: At SRON we have been developing X-ray TES micro-calorimeters as backup technology for the X-ray Integral Field Unit (X-IFU) of the Athena mission, demonstrating excellent resolving powers both under DC and AC bias. We also developed a frequency-domain multiplexing (FDM) readout technology, where each TES is coupled to a superconducting band-pass LC resonator and AC biased at MHz frequencies throug… ▽ More At SRON we have been developing X-ray TES micro-calorimeters as backup technology for the X-ray Integral Field Unit (X-IFU) of the Athena mission, demonstrating excellent resolving powers both under DC and AC bias. We also developed a frequency-domain multiplexing (FDM) readout technology, where each TES is coupled to a superconducting band-pass LC resonator and AC biased at MHz frequencies through a common readout line. The TES signals are summed at the input of a superconducting quantum interference device (SQUID), which performs a first amplification at cryogenic stage. Custom analog front-end electronics and digital boards take care of further amplifying the signals at room temperature and of the modulation/demodulation of the TES signals and bias carrier, respectively. We report on the most recent developments on our FDM technology, which involves a two-channel demonstration with a total of 70 pixels with a summed energy resolution of 2.34 +/- 0.02 eV at 5.9 keV without spectral performance degradation with respect to single-channel operation. Moreover, we discuss prospects towards the scaling-up to a larger multiplexing factor up to 78 pixels per channel in a 1-6 MHz readout bandwidth. △ Less

Submitted 5 March, 2024; originally announced March 2024.

Comments: Under publication in Journal of Low Temperature Physics

System performance of a TDM test-bed with long flex harness towards the new X-IFU FPA-DM

Authors: D. Vaccaro, M. de Wit, J. van der Kuur, L. Gottardi, K. Ravensberg, E. Taralli, J. Adams, S. R. Bandler, J. A. Chervenak, W. B. Doriese, M. Durkin, C. Reintsema, K. Sakai, S. J. Smith, N. A. Wakeham, B. Jackson, P. Khosropanah, J. R. Gao, J. W. A. den Herder, P. Roelfsema

Abstract: SRON (Netherlands Institute for Space Research) is developing the Focal Plane Assembly (FPA) for Athena X-IFU, whose Demonstration Model (DM) will use for the first time a time domain multiplexing (TDM)-based readout system for the on-board transition-edge sensors (TES). We report on the characterization activities on a TDM setup provided by NASA Goddard Space Flight Center (GSFC) and National Ins… ▽ More SRON (Netherlands Institute for Space Research) is developing the Focal Plane Assembly (FPA) for Athena X-IFU, whose Demonstration Model (DM) will use for the first time a time domain multiplexing (TDM)-based readout system for the on-board transition-edge sensors (TES). We report on the characterization activities on a TDM setup provided by NASA Goddard Space Flight Center (GSFC) and National Institute for Standards and Technology (NIST) and tested in SRON cryogenic test facilities. The goal of these activities is to study the impact of the longer harness, closer to X-IFU specs, in a different EMI environment and switching from a single-ended to a differential readout scheme. In this contribution we describe the advancement in the debugging of the system in the SRON cryostat, which led to the demonstration of the nominal spectral performance of 2.8 eV at 5.9~keV with 16-row multiplexing, as well as an outlook for the future endeavours for the TDM readout integration on X-IFU's FPA-DM at SRON. △ Less

Submitted 5 March, 2024; originally announced March 2024.

Comments: Under publication in Journal of Low Temperature Physics

AT2023lli: A Tidal Disruption Event with Prominent Optical Early Bump and Delayed Episodic X-ray Emission

Authors: Shifeng Huang, Ning Jiang, Jiazheng Zhu, Yibo Wang, Tinggui Wang, Shan-Qin Wang, Wen-Pei Gan, En-Wei Liang, Yu-Jing Qin, Zheyu Lin, Lin-Na Xu, Min-Xuan Cai, Ji-An Jiang, Xu Kong, Jiaxun Li, Long Li, Jian-Guo Wang, Ze-Lin Xu, Yongquan Xue, Ye-Fei Yuan, Jingquan Cheng, Lulu Fan, Jie Gao, Lei Hu, Weida Hu , et al. (20 additional authors not shown)

Abstract: High-cadence, multiwavelength observations have continuously revealed the diversity of tidal disruption events (TDEs), thus greatly advancing our knowledge and understanding of TDEs. In this work, we conducted an intensive optical-UV and X-ray follow-up campaign of TDE AT2023lli, and found a remarkable month-long bump in its UV/optical light curve nearly two months prior to maximum brightness. The… ▽ More High-cadence, multiwavelength observations have continuously revealed the diversity of tidal disruption events (TDEs), thus greatly advancing our knowledge and understanding of TDEs. In this work, we conducted an intensive optical-UV and X-ray follow-up campaign of TDE AT2023lli, and found a remarkable month-long bump in its UV/optical light curve nearly two months prior to maximum brightness. The bump represents the longest separation time from the main peak among known TDEs to date. The main UV/optical outburst declines as $t^{-4.10}$, making it one of the fastest decaying optically selected TDEs. Furthermore, we detected sporadic X-ray emission 30 days after the UV/optical peak, accompanied by a reduction in the period of inactivity. It is proposed that the UV/optical bump could be caused by the self-intersection of the stream debris, whereas the primary peak is generated by the reprocessed emission of the accretion process. In addition, our results suggest that episodic X-ray radiation during the initial phase of decline may be due to the patched obscurer surrounding the accretion disk, a phenomenon associated with the inhomogeneous reprocessing process. The double TDE scenario, in which two stars are disrupted in sequence, is also a possible explanation for producing the observed early bump and main peak. We anticipate that the multicolor light curves of TDEs, especially in the very early stages, and the underlying physics can be better understood in the near future with the assistance of dedicated surveys such as the deep high-cadence survey of the 2.5-meter Wide Field Survey Telescope (WFST). △ Less

Submitted 26 March, 2024; v1 submitted 3 March, 2024; originally announced March 2024.

Comments: 14 pages, 8 figures,accepted for publication by ApJL

Evolved Massive Stars at Low-metallicity VII. the Lower Mass Limit of Red Supergiant Population in the Large Magellanic Cloud

Authors: Ming Yang, Bo Zhang, Biwei Jiang, Jian Gao, Yi Ren, Shu Wang, Man I Lam, Hao Tian, Changqing Luo, Bingqiu Chen, Jing Wen

Abstract: The precise definition of the lower mass limit of red supergiant stars (RSGs) is an open question in astrophysics and does not attract too much attention. Here we assemble a spectroscopic evolved cool star sample with 6,602 targets, including RSGs, asymptotic giant branch stars, and red giant branch stars, in the Large Magellanic Cloud based on \textit{Gaia} DR3 and SDSS-IV/APOGEE-2. The reference… ▽ More The precise definition of the lower mass limit of red supergiant stars (RSGs) is an open question in astrophysics and does not attract too much attention. Here we assemble a spectroscopic evolved cool star sample with 6,602 targets, including RSGs, asymptotic giant branch stars, and red giant branch stars, in the Large Magellanic Cloud based on \textit{Gaia} DR3 and SDSS-IV/APOGEE-2. The reference spectrum of each stellar population is built according to the quantile range of relative intensity ($1\%\sim99\%$). Five different methods, e.g., chi-square ($χ^2$), cosine similarity (CS), machine learning (ML), equivalent width (EW), and line ratio (LR), are used in order to separate different stellar populations. The ML and $χ^2$ provide the best and relatively consistent prediction of certain population. The derived lower limit of the RSG population is able to reach to the $\rm K_S$-band tip of red giant branch ($\rm K_S~$$\approx12.0$ mag), indicating a luminosity as low as about $10^{3.5}~L_{\sun}$, which corresponds to a stellar radius only about $100~R_{\sun}$. Given the mass-luminosity relation of $L/L_\sun =f(M/M_\sun)^3$ with $f\approx15.5\pm3$ and taking into account of the mass loss of faint RSGs up to now, the minimal initial mass of the RSG population would be about $6.1\pm0.4~M_\sun$, which is much lower than the traditional threshold of $8~M_\sun$ for the massive stars. This is the first spectroscopic evidence, indicating that the lower mass limit of RSG population is around $6~M_\sun$. However, the destinies of such faint RSGs are still elusive and may have large impact on the stellar evolutionary and supernova models. △ Less

Submitted 28 January, 2024; originally announced January 2024.

Comments: 33 pages, 34 figures, ApJ accepted

Bayesian parameter estimation of massive black hole binaries with TianQin-LISA

Authors: Jie Gao, Yi-Ming Hu, En-Kun Li, Jian-dong Zhang, Jianwei Mei

Abstract: This paper analyses the impact of various parameter changes on the estimation of parameters for massive black hole binary (MBHB) systems using a Bayesian inference technique. Several designed MBHB systems were chosen for comparison with a fiducial system to explore the influence of parameters such as sky location, inclination angle, anti-spin, large mass ratio and light mass. And the two reported… ▽ More This paper analyses the impact of various parameter changes on the estimation of parameters for massive black hole binary (MBHB) systems using a Bayesian inference technique. Several designed MBHB systems were chosen for comparison with a fiducial system to explore the influence of parameters such as sky location, inclination angle, anti-spin, large mass ratio and light mass. And the two reported MBHB candidates named OJ287 and Tick-Tock are also considered. The study found that the network of TianQin and LISA can break certain degeneracies among different parameters, improving the estimation of parameters, particularly for extrinsic parameters. Meanwhile, the degeneracies between different intrinsic parameters are highly sensitive to the value of the parameters. Additionally, the small inclination angles and limited detection of the inspiral phase can introduce significant bias in the estimation of parameters. The presence of instrument noise will also introduce bias and worsen the precision. The paper concludes that the network of TianQin and LISA can significantly improve the estimation of extrinsic parameters by about one order of magnitude while yielding slight improvements in the intrinsic parameters. Moreover, parameter estimation can still be subject to biases even with a sufficiently high signal-to-noise ratio if the detected signal does not encompass all stages of the inspiral, merger, and ringdown. △ Less

Submitted 23 January, 2024; originally announced January 2024.

Comments: 17 pages, 10 figures

Evolved Massive Stars at Low-metallicity VI. Mass-Loss Rate of Red Supergiant Stars in the Large Magellanic Cloud

Authors: Jing Wen, Jian Gao, Ming Yang, Bingqiu Chen, Yi Ren, Tianding Wang, Biwei Jiang

Abstract: Mass loss is a crucial process that affects the observational properties, evolution path and fate of highly evolved stars. However, the mechanism of mass loss is still unclear, and the mass-loss rate (MLR) of red supergiant stars (RSGs) requires further research and precise evaluation. To address this, we utilized an updated and complete sample of RSGs in the Large Magellanic Cloud (LMC) and emplo… ▽ More Mass loss is a crucial process that affects the observational properties, evolution path and fate of highly evolved stars. However, the mechanism of mass loss is still unclear, and the mass-loss rate (MLR) of red supergiant stars (RSGs) requires further research and precise evaluation. To address this, we utilized an updated and complete sample of RSGs in the Large Magellanic Cloud (LMC) and employed the 2-DUST radiation transfer model and spectral energy distribution (SED) fitting approach to determine the dust-production rates (DPRs) and dust properties of the RSGs. We have fitted 4,714 selected RSGs with over 100,000 theoretical templates of evolved stars. Our results show that the DPR range of RSGs in the LMC is $10^{-11}\, \rm{M_{\odot}\, yr^{-1}}$ to $10^{-7}\, \rm{M_{\odot}\, yr^{-1}}$, and the total DPR of all RSGs is 1.14 $\times 10^{-6} \, \rm{M_{\odot} \, yr^{-1}}$. We find that $63.3\%$ RSGs are oxygen-rich, and they account for $97.2\%$ of the total DPR. The optically thin RSG, which comprise $30.6\%$ of our sample, contribute only $0.1\%$ of the total DPR, while carbon-rich RSGs ($6.1\%$) produce $2.7\%$ of the total DPR. Overall, 208 RSGs contributed $76.6\%$ of the total DPR. We have established a new relationship between the MLR and luminosity of RSGs in the LMC, which exhibits a positive trend and a clear turning point at $\log{L/L_{\odot}} \approx 4.4$. △ Less

Submitted 8 January, 2024; originally announced January 2024.

Comments: Accepted for publication in AJ

Coupled Dark Sector Models and Cosmological Tensions

Authors: Gang Liu, Jiaze Gao, Yufen Han, Yuhao Mu, Lixin Xu

Abstract: In this paper, we introduce two coupling models of early dark energy (EDE) and cold dark matter aimed at alleviating cosmological tensions. We utilize the EDE component in the coupling models to relieve the Hubble tension, while leveraging the interaction between dark matter and dark energy to alleviate the large-scale structure tension. The interaction is implemented in the form of pure momentum… ▽ More In this paper, we introduce two coupling models of early dark energy (EDE) and cold dark matter aimed at alleviating cosmological tensions. We utilize the EDE component in the coupling models to relieve the Hubble tension, while leveraging the interaction between dark matter and dark energy to alleviate the large-scale structure tension. The interaction is implemented in the form of pure momentum coupling and Yukawa coupling. We employed various cosmological datasets, including cosmic microwave background radiation, baryon acoustic oscillations, Type Ia supernovae, the local distance-ladder data (SH0ES), and the Dark Energy Survey Year-3 data, to analyze our models. We first exclude SH0ES data from the entire dataset to constrain the parameters of novel models. We observe that the constraints on $H_0$ from two coupling models are slightly higher than that from the $Λ$CDM model, but they exhibit a significant inconsistency with the SH0ES data, consistent with prior research findings in the EDE model. Subsequently, we incorporate SH0ES data to re-constrain the parameters of various models, our findings reveal that both coupling models yield best-fit values for $H_0$ approximately around $72.23$ km/s/Mpc, effectively mitigating the Hubble tension. Similar to the EDE model, the coupling models yield the $S_8$ values that still surpasses the result of the $Λ$CDM model. Nevertheless, the best-fit values for $S_8$ obtained with the two new models are 0.8192 and 0.8177, respectively, which are lower than the 0.8316 achieved by the EDE model. Consequently, although our coupling models fail to fully resolve the large-scale structure tension, they partially mitigate the adverse effect of the original EDE model. △ Less

Submitted 23 April, 2024; v1 submitted 3 December, 2023; originally announced December 2023.

Comments: 14 pages, 9 figures. In this replacement, we have amalgamated the original content of this manuscript with that of a previous paper [arXiv:2310.09798]. arXiv admin note: substantial text overlap with arXiv:2310.09798

Journal ref: Phys. Rev. D 109, 103531 (2024)

Detection of magnetospheric ion drift patterns at Mars

Authors: Chi Zhang, Hans Nilsson, Yusuke Ebihara, Masatoshi Yamauchi, Moa Persson, Zhaojin Rong, Jun Zhong, Chuanfei Dong, Yuxi Chen, Xuzhi Zhou, Yixin Sun, Yuki Harada, Jasper Halekas, Shaosui Xu, Yoshifumi Futaana, Zhen Shi, Chongjing Yuan, Xiaotong Yun, Song Fu, Jiawei Gao, Mats Holmström, Yong Wei, Stas Barabash

Abstract: Mars lacks a global magnetic field, and instead possesses small-scale crustal magnetic fields, making its magnetic environment fundamentally different from intrinsic magnetospheres like those of Earth or Saturn. Here we report the discovery of magnetospheric ion drift patterns, typical of intrinsic magnetospheres, at Mars usingmeasurements fromMarsAtmosphere and Volatile EvolutioNmission. Specific… ▽ More Mars lacks a global magnetic field, and instead possesses small-scale crustal magnetic fields, making its magnetic environment fundamentally different from intrinsic magnetospheres like those of Earth or Saturn. Here we report the discovery of magnetospheric ion drift patterns, typical of intrinsic magnetospheres, at Mars usingmeasurements fromMarsAtmosphere and Volatile EvolutioNmission. Specifically, we observewedge-like dispersion structures of hydrogen ions exhibiting butterfly-shaped distributions within the Martian crustal fields, a feature previously observed only in planetary-scale intrinsic magnetospheres. These dispersed structures are the results of driftmotions that fundamentally resemble those observed in intrinsic magnetospheres. Our findings indicate that the Martian magnetosphere embodies an intermediate case where both the unmagnetized and magnetized ion behaviors could be observed because of the wide range of strengths and spatial scales of the crustal magnetic fields around Mars. △ Less

Submitted 10 November, 2023; originally announced November 2023.

Comments: 10 pages, 6 figures

Mitigating Cosmological Tensions via Momentum-Coupled Dark Sector Model

Authors: Gang Liu, Jiaze Gao, Yufen Han, Yuhao Mu, Lixin Xu

Abstract: In this paper, we investigate the momentum coupling between early dark energy (EDE) and cold dark matter to alleviate cosmological tensions. EDE has exhibited promising efficacy in addressing the Hubble tension, but it exacerbates the large-scale structure tension. We consider the interaction between EDE and cold dark matter, introducing a pure momentum exchange between them to alleviate the large… ▽ More In this paper, we investigate the momentum coupling between early dark energy (EDE) and cold dark matter to alleviate cosmological tensions. EDE has exhibited promising efficacy in addressing the Hubble tension, but it exacerbates the large-scale structure tension. We consider the interaction between EDE and cold dark matter, introducing a pure momentum exchange between them to alleviate the large-scale structure tension introduced by the EDE model. We find that this coupling model is consistent with the EDE model, yielding a higher value for $H_0$, which can resolve the Hubble tension. Additionally, the new model exhibits a suppressive effect on structure growth, contributing to the alleviation of the large-scale structure tension. By utilizing the Markov Chain Monte Carlo method and incorporating various cosmological data, the coupling model constrains the best-fit values for $H_0$ to be $72.23$ km/s/Mpc and for $S_8$ to be 0.8192. Compared to the $Λ$CDM model, the new models have not fully resolved the large-scale structure tension. However, in contrast to the best-fit value of 0.8316 for $S_8$ obtained from the EDE model, the new model alleviates the negative impact of the EDE model. △ Less

Submitted 24 April, 2024; v1 submitted 15 October, 2023; originally announced October 2023.

Comments: This paper has been merged into the latest version of another paper, [arXiv:2312.01410]

Compact Metasurface Terahertz Spectrometer

Authors: Wenye Ji, Jin Chang, Behnam Mirzaei, Marcel Ridder, Willem Jellema, Wilt Kao, Alan Lee, Jian Rong Gao, Paul Urbach, Aurele J. L. Adam

Abstract: The electromagnetic spectrum in the terahertz frequency region is of significant importance for understanding the formation and evolution of galaxies and stars throughout the history of the universe and the process of planet formation. Within the star forming clouds the constituent atoms and molecules are excited to produce characteristic emission and absorption lines, many of which happen at the… ▽ More The electromagnetic spectrum in the terahertz frequency region is of significant importance for understanding the formation and evolution of galaxies and stars throughout the history of the universe and the process of planet formation. Within the star forming clouds the constituent atoms and molecules are excited to produce characteristic emission and absorption lines, many of which happen at the terahertz frequencies. Thus, detecting the spectral signatures as unique fingerprints of molecules and atoms require terahertz spectrometers, which need to be operated in a space observatory because of the water vapor absorption in the earth atmosphere. However, current terahertz spectrometers face several challenges that limit their performances and applications, including a low resolution, limited bandwidth, large volume, and complexity. In this paper, we address the last two issues by demonstrating a concept of a compact terahertz spectrometer using metasurface. We start by modelling, designing, and fabricating a metasurface, aiming to optimize its performance within a band from 1.7 to 2.5 THz. Next, we make use of an array of quantum cascade lasers that operate at slightly different frequencies around 2.1 THz to validate the performance of the spectrometer. Finally, we apply the spectrum inversion method to analyse the measured data to confirm a resolution R of at least 273. Our results demonstrated a miniaturized terahertz spectrometer concept successfully. △ Less

Submitted 5 September, 2023; originally announced September 2023.

Astrometric mass measurement of compact companions in binary systems with Gaia

Authors: Yilun Wang, Shilong Liao, Nicola Giacobbo, Aleksandra Olejak, Jian Gao, Jifeng Liu

Abstract: For binary systems with an unseen primary and a luminous secondary, the astrometric wobble of the secondary could be used to study the primary. With Gaia, it is possible to measure the mass of the black hole or neutron star with a luminous companion (hereafter BH/NS-LC). Our aim is to provide a method for predicting Gaia's ability in measuring the mass of BH/NS-LCs. We also tried to estimate the n… ▽ More For binary systems with an unseen primary and a luminous secondary, the astrometric wobble of the secondary could be used to study the primary. With Gaia, it is possible to measure the mass of the black hole or neutron star with a luminous companion (hereafter BH/NS-LC). Our aim is to provide a method for predicting Gaia's ability in measuring the mass of BH/NS-LCs. We also tried to estimate the number of solvable BH/NS-LCs using Gaia. We used a realistic Markov chain Monte Carlo simulation of mock Gaia observations to obtain a relation between the uncertainty of mass measurement of the primary in BH/NS-LCs with the observable variables of the secondary astrometric orbit. Furthermore, we used the MOBSE code to evolve a Galactic BH/NS-LC sample with a combined Milky Way model. Our relation is applied to this sample to estimate the number of solvable BH/NS-LCs. We derived a good relation between the mass uncertainty and the binary parameters. For the first time, we show the quantitive influence of the period P, inclination i, eccentricity e, and ecliptic latitude $β$ to the mass measurement. Our results suggest that $48^{+7}_{-7}$ BH-LCs and $102^{+11}_{10}$ NS-LCs are solvable during a 5 yr Gaia mission. We also give the distribution of the distance and apparent magnitude of the Gaia solvable BH/NS-LCs. This solvable sample would be increased by additional spectroscopic data or a prolonged Gaia mission. The mass uncertainty relation could be used in future simulations of BH/NS-LCs observed by Gaia. The prediction of the solvable BH/NS-LCs is not only influenced by the process in generating the Galactic BH/NS-LC sample, but is also affected by our uncertainty relation. In particular, the relations of parameters such as $[P, e, i, β]$ are very useful to correct the selection effect in the statistic results of the future BH/NS-LC sample observed by Gaia. △ Less

Submitted 24 July, 2023; originally announced July 2023.

Journal ref: A&A, 665 (2022) A111

A Measurement of Hubble Constant Using Cosmographic Approach from Fast Radio Bursts and SNe Ia

Authors: Jiaze Gao, Zhihuan Zhou, Minghui Du, Rui Zou, Jianping Hu, Lixin Xu

Abstract: The Hubble constant ${H}_0$ is a crucial parameter in cosmology. However, different cosmic observations have resulted in varying posterior results for ${H}_0$, leading to what is known as the ${H}_0$ tension. In order to address this issue, it is beneficial to use other dataset to constrain ${H}_0$. In this paper, via the cosmographic approach based on the Friedman-Lemaitre-Robertson-Walker (FLRW)… ▽ More The Hubble constant ${H}_0$ is a crucial parameter in cosmology. However, different cosmic observations have resulted in varying posterior results for ${H}_0$, leading to what is known as the ${H}_0$ tension. In order to address this issue, it is beneficial to use other dataset to constrain ${H}_0$. In this paper, via the cosmographic approach based on the Friedman-Lemaitre-Robertson-Walker (FLRW) metric to the dispersion measure of the intergalactic medium ${\rm{DM}}_{\rm{IGM}}(z)$ of Fast Radio Bursts (FRBs), we obtain the Taylor expansion of $\langle{\rm{DM}}_{\rm{IGM}}(z)\rangle$ in terms redshift $z$. The result for Hubble constant $H_0=65.5^{+6.4}_{-5.4}$ ${\rm{km~s^{-1}~Mpc^{-1}}}$ $(68$$\%$ ${\rm{C.L.}}) $, cosmological deceleration parameter $q_0=-0.50\pm 0.20 $ and the jerk parameter $j_0=-0.1^{+2.0}_{-2.5}$ using uncalibrated Supernova Ia (SNe Ia) Pantheon dataset combined with 18 localized FRBs are obtained. To demonstrate the impact of parameter degeneracies on our analysis methods, we compare the results using three different forms of $f_{\rm{IGM}}(z)$ and two different prior distributions for $Ω_{\rm{b,0}}$. Then we find that the uncertainty in $H_0$ is not significantly affected by the prior range of $f_{\rm{IGM}}(z)$ and $Ω_{\rm{b,0}}$, but the mean value is influenced by the priors for $f_{\rm{IGM}}(z)$ and $Ω_{\rm{b,0}}$ due to parameter degeneracies with $H_0$. Employing $f_{\rm{IGM}}(z)$ that evolves with redshift, we obtain the constraints for $H_0=69.0^{+6.7}_{-5.7}$ ${\rm{km~s^{-1}~Mpc^{-1}}}$. Furthermore, the mock analyses give a posterior estimation of $H_0$ with an accuracy of 4.6\% and higher precision for $q_0$ and $j_0$ in the near future. △ Less

Submitted 17 July, 2023; originally announced July 2023.

Search for astrophysical electron antineutrinos in Super-Kamiokande with 0.01wt% gadolinium-loaded water

Authors: M. Harada, K. Abe, C. Bronner, Y. Hayato, K. Hiraide, K. Hosokawa, K. Ieki, M. Ikeda, J. Kameda, Y. Kanemura, R. Kaneshima, Y. Kashiwagi, Y. Kataoka, S. Miki, S. Mine, M. Miura, S. Moriyama, Y. Nakano, M. Nakahata, S. Nakayama, Y. Noguchi, K. Okamoto, K. Sato, H. Sekiya, H. Shiba , et al. (216 additional authors not shown)

Abstract: We report the first search result for the flux of astrophysical electron antineutrinos for energies O(10) MeV in the gadolinium-loaded Super-Kamiokande (SK) detector. In June 2020, gadolinium was introduced to the ultra-pure water of the SK detector in order to detect neutrons more efficiently. In this new experimental phase, SK-Gd, we can search for electron antineutrinos via inverse beta decay w… ▽ More We report the first search result for the flux of astrophysical electron antineutrinos for energies O(10) MeV in the gadolinium-loaded Super-Kamiokande (SK) detector. In June 2020, gadolinium was introduced to the ultra-pure water of the SK detector in order to detect neutrons more efficiently. In this new experimental phase, SK-Gd, we can search for electron antineutrinos via inverse beta decay with efficient background rejection and higher signal efficiency thanks to the high efficiency of the neutron tagging technique. In this paper, we report the result for the initial stage of SK-Gd with a $22.5\times552$ $\rm kton\cdot day$ exposure at 0.01% Gd mass concentration. No significant excess over the expected background in the observed events is found for the neutrino energies below 31.3 MeV. Thus, the flux upper limits are placed at the 90% confidence level. The limits and sensitivities are already comparable with the previous SK result with pure-water ($22.5 \times 2970 \rm kton\cdot day$) owing to the enhanced neutron tagging. △ Less

Submitted 30 May, 2023; v1 submitted 8 May, 2023; originally announced May 2023.

Bayesian Inference of Supernova Neutrino Spectra with Multiple Detectors

Authors: Xu-Run Huang, Chuan-Le Sun, Lie-Wen Chen, Jun Gao

Abstract: We implement the Bayesian inference to retrieve energy spectra of all neutrinos from a galactic core-collapse supernova (CCSN). To achieve high statistics and full sensitivity to all flavours of neutrinos, we adopt a combination of several reaction channels from different large-scale neutrino observatories, namely inverse beta decay on proton and elastic scattering on electron from Hyper-Kamiokand… ▽ More We implement the Bayesian inference to retrieve energy spectra of all neutrinos from a galactic core-collapse supernova (CCSN). To achieve high statistics and full sensitivity to all flavours of neutrinos, we adopt a combination of several reaction channels from different large-scale neutrino observatories, namely inverse beta decay on proton and elastic scattering on electron from Hyper-Kamiokande (Hyper-K), charged current absorption on Argon from Deep Underground Neutrino Experiment (DUNE) and coherent elastic scattering on Lead from RES-NOVA. Assuming no neutrino oscillation or specific oscillation models, we obtain mock data for each channel through Poisson processes with the predictions, for a typical source distance of 10 kpc in our Galaxy, and then evaluate the probability distributions for all spectral parameters of theoretical neutrino spectrum model with Bayes' theorem. Although the results for either the electron-neutrinos or electron-antineutrinos reserve relatively large uncertainties (according to the neutrino mass hierarchy), a precision of a few percent (i.e., $\pm 1 \% \sim \pm 4 \%$ at a credible interval of $2 σ$) is achieved for primary spectral parameters (e.g., mean energy and total emitted energy) of other neutrino species. Moreover, the correlation coefficients between different parameters are computed as well and interesting patterns are found. Especially, the mixing-induced correlations are sensitive to the neutrino mass hierarchy, which potentially makes it a brand new probe to determine the neutrino mass hierarchy in the detection of galactic supernova neutrinos. Finally, we discuss the origin of such correlation patterns and perspectives for further improvement on our results. △ Less

Submitted 24 September, 2023; v1 submitted 30 April, 2023; originally announced May 2023.

Comments: 25 pages, 7 figures, 4 tables, published version

Journal ref: JCAP09(2023)040

Evolved Massive Stars at Low-metallicity V. Mass-Loss Rate of Red Supergiant Stars in the Small Magellanic Cloud

Authors: Ming Yang, Alceste Z. Bonanos, Biwei Jiang, Emmanouil Zapartas, Jian Gao, Yi Ren, Man I Lam, Tianding Wang, Grigoris Maravelias, Panagiotis Gavras, Shu Wang, Xiaodian Chen, Frank Tramper, Stephan de Wit, Bingqiu Chen, Jing Wen, Jiaming Liu, Hao Tian, Konstantinos Antoniadis, Changqing Luo

Abstract: We assemble the most complete and clean red supergiant (RSG) sample (2,121 targets) so far in the Small Magellanic Cloud (SMC) with 53 different bands of data to study the MLR of RSGs. In order to match the observed spectral energy distributions (SEDs), a theoretical grid of 17,820 Oxygen-rich models (``normal'' and ``dusty'' grids are half-and-half) is created by the radiatively-driven wind model… ▽ More We assemble the most complete and clean red supergiant (RSG) sample (2,121 targets) so far in the Small Magellanic Cloud (SMC) with 53 different bands of data to study the MLR of RSGs. In order to match the observed spectral energy distributions (SEDs), a theoretical grid of 17,820 Oxygen-rich models (``normal'' and ``dusty'' grids are half-and-half) is created by the radiatively-driven wind model of the DUSTY code, covering a wide range of dust parameters. We select the best model for each target by calculating the minimal modified chi-square and visual inspection. The resulting MLRs from DUSTY are converted to real MLRs based on the scaling relation, for which a total MLR of $6.16\times10^{-3}$ $M_\odot$ yr$^{-1}$ is measured (corresponding to a dust-production rate of $\sim6\times10^{-6}$ $M_\odot$ yr$^{-1}$), with a typical MLR of $\sim10^{-6}$ $M_\odot$ yr$^{-1}$ for the general population of the RSGs. The complexity of mass-loss estimation based on the SED is fully discussed for the first time, indicating large uncertainties based on the photometric data (potentially up to one order of magnitude or more). The Hertzsprung-Russell and luminosity versus median absolute deviation diagrams of the sample indicate the positive relation between luminosity and MLR. Meanwhile, the luminosity versus MLR diagrams show a ``knee-like'' shape with enhanced mass-loss occurring above $\log_{10}(L/L_\odot)\approx4.6$, which may be due to the degeneracy of luminosity, pulsation, low surface gravity, convection, and other factors. We derive our MLR relation by using a third-order polynomial to fit the sample and compare our result with previous empirical MLR prescriptions. Given that our MLR prescription is based on a much larger sample than previous determinations, it provides a more accurate relation at the cool and luminous region of the H-R diagram at low-metallicity compared to previous studies. △ Less

Submitted 4 April, 2023; originally announced April 2023.

Comments: 16 pages, 19 figures, accepted by A&A

Journal ref: A&A 676, A84 (2023)

Improved microwave SQUID multiplexer readout using a kinetic-inductance traveling-wave parametric amplifier

Authors: M. Malnou, J. A. B. Mates, M. R. Vissers, L. R. Vale, D. R. Schmidt, D. A. Bennett, J. Gao, J. N. Ullom

Abstract: We report on the use of a kinetic-inductance traveling-wave parametric amplifier (KITWPA) as the first amplifier in the readout chain of a microwave superconducting quantum interference device (SQUID) multiplexer (umux). This umux is designed to multiplex signals from arrays of low temperature detectors such as superconducting transition-edge sensor microcalorimeters. When modulated with a periodi… ▽ More We report on the use of a kinetic-inductance traveling-wave parametric amplifier (KITWPA) as the first amplifier in the readout chain of a microwave superconducting quantum interference device (SQUID) multiplexer (umux). This umux is designed to multiplex signals from arrays of low temperature detectors such as superconducting transition-edge sensor microcalorimeters. When modulated with a periodic flux-ramp to linearize the SQUID response, the flux noise improves, on average, from $1.6$ $μΦ_0/\sqrt{\mathrm{Hz}}$ with the KITWPA off, to $0.77$ $μΦ_0/\sqrt{\mathrm{Hz}}$ with the KITWPA on. When statically biasing the umux to the maximally flux-sensitive point, the flux noise drops from $0.45$ $μΦ_0/\sqrt{\mathrm{Hz}}$ to $0.2$ $μΦ_0/\sqrt{\mathrm{Hz}}$. We validate this new readout scheme by coupling a transition-edge sensor microcalorimeter to the umux and detecting background radiation. The combination of umux and KITWPA provides a variety of new capabilities including improved detector sensitivity and more efficient bandwidth utilization. △ Less

Submitted 7 March, 2023; originally announced March 2023.