Showing 1–50 of 185 results for author: Yu, C

The Simons Observatory: forecasted constraints on primordial gravitational waves with the expanded array of Small Aperture Telescopes

Authors: The Simons Observatory Collaboration, I. Abril-Cabezas, S. Adachi, P. Ade, A. E. Adler, P. Agrawal, J. Aguirre, S. Aiola, T. Alford, A. Ali, D. Alonso, M. A. Alvarez, R. An, M. Aravena, K. Arnold, P. Ashton, F. Astori, Z. Atkins, J. Austermann, S. Azzoni, C. Baccigalupi, D. Baker, R. Balafendiev, A. Baleato Lizancos, D. Barron , et al. (457 additional authors not shown)

Abstract: We present updated forecasts for the scientific performance of the degree-scale (0.5 deg FWHM at 93 GHz), deep-field survey to be conducted by the Simons Observatory (SO). By 2027, the SO Small Aperture Telescope (SAT) complement will be doubled from three to six telescopes, including a doubling of the detector count in the 93 GHz and 145 GHz channels to 48,160 detectors. Combined with a planned e… ▽ More We present updated forecasts for the scientific performance of the degree-scale (0.5 deg FWHM at 93 GHz), deep-field survey to be conducted by the Simons Observatory (SO). By 2027, the SO Small Aperture Telescope (SAT) complement will be doubled from three to six telescopes, including a doubling of the detector count in the 93 GHz and 145 GHz channels to 48,160 detectors. Combined with a planned extension of the survey duration to 2035, this expansion will significantly enhance SO's search for a $B$-mode signal in the polarisation of the cosmic microwave background, a potential signature of gravitational waves produced in the very early Universe. Assuming a $1/f$ noise model with knee multipole $\ell_{\rm knee} = 50$ and a moderately complex model for Galactic foregrounds, we forecast a $1σ$ (or 68% confidence level) constraint on the tensor-to-scalar ratio $r$ of $σ_r = 1.2\times10^{-3}$, assuming no primordial $B$-modes are present. This forecast assumes that 70% of the $B$-mode lensing signal can ultimately be removed using high resolution observations from the SO Large Aperture Telescope (LAT) and overlapping large-scale structure surveys. For more optimistic assumptions regarding foregrounds and noise, and assuming the same level of delensing, this forecast constraint improves to $σ_r = 7\times10^{-4}$. These forecasts represent a major improvement in SO's constraining power, being a factor of around 2.5 times better than what could be achieved with the originally planned campaign, which assumed the existing three SATs would conduct a five-year survey. △ Less

Submitted 17 December, 2025; originally announced December 2025.

Comments: 15 pages (excluding front matter), 4 figures, for submission to JCAP

TDLight: A Framework for Incremental Light Curve Management and Smart Classification

Authors: Xinghang Yu, Ce Yu, Zeguang Shao, Bin Yang

Abstract: With the exponential growth of time-domain surveys, the volume of light curves has increased rapidly. However, many survey projects, such as Gaia, still rely on offline batch-processing workflows in which data are calibrated, merged, and released only after an observing phase is completed. This latency delays scientific analysis and causes many high-value transient events to be buried in archival… ▽ More With the exponential growth of time-domain surveys, the volume of light curves has increased rapidly. However, many survey projects, such as Gaia, still rely on offline batch-processing workflows in which data are calibrated, merged, and released only after an observing phase is completed. This latency delays scientific analysis and causes many high-value transient events to be buried in archival data, missing the window for timely follow-up. While existing alert brokers handle heterogeneous data streams, it remains difficult to deploy a unified framework that combines high-performance incremental storage with real-time classification on local infrastructure. To address this challenge, we propose TDLight, a scalable system that adapts the time-series database TDengine (a high-performance IoT database) for astronomical data using a one-table-per-source schema. This architecture supports high-throughput ingestion, achieving 954,000 rows s^-1 for archived data and 541,000 rows s^-1 for incremental streams, while Hierarchical Equal Area isoLatitude Pixelization (HEALPix) indexing enables efficient cone-search queries. Building on this storage layer, we integrate the pre-trained hierarchical Random Forest classifier from the LEAVES framework to construct an incremental classification pipeline. Using the LEAVES dataset, we simulate data accumulation and evaluate a trigger-based strategy that performs early classification at specific observational milestones. In addition, by monitoring the evolution of classification probabilities, the system identifies "high-value candidates" -- sources that show high early confidence but later undergo significant label shifts. TDLight is released as an open-source Dockerized environment, providing a deployable infrastructure for next-generation time-domain surveys. △ Less

Submitted 24 November, 2025; originally announced November 2025.

Comments: 8 pages, 6 figures

The Dynamical Interaction between Low-mass Planets and Dust Coagulation

Authors: Qiang Hou, Cong Yu, Shu-ichiro Inutsuka

Abstract: We investigate the impact of a low-mass planet on dust coagulation, and its consequent feedback on planetary migration, using a linear analysis of the coupled dust-gas hydrodynamic equations. Dust coagulation is incorporated via a single-size approximation. In the co-orbital region of the planet, we find that the growth of dust size is significantly suppressed by planet-induced coagulation modes (… ▽ More We investigate the impact of a low-mass planet on dust coagulation, and its consequent feedback on planetary migration, using a linear analysis of the coupled dust-gas hydrodynamic equations. Dust coagulation is incorporated via a single-size approximation. In the co-orbital region of the planet, we find that the growth of dust size is significantly suppressed by planet-induced coagulation modes (CMs). This effect are less pronounced with smaller stopping times, stronger gaseous turbulence or imperfect sticking. Regarding planetary migration, we find that CMs make outward migration require $τ\gtrsim 0.3$ ($τ$ is dimensionless stopping time) with typical turbulent strength and dust coagulation efficiency. We demonstrate that the torque variations are reasonable and arise from phase shifts between the density and stopping time perturbations in the coagulation modes. △ Less

Submitted 24 November, 2025; originally announced November 2025.

Comments: Accepted for publication in ApJ Letters

Irradiated Atmospheres IV: Effect of Mixing Heat Flux on Chemistry

Authors: Zhen-Tai Zhang, Wei Zhong, Wei Wang, Jianheng Guo, Xianyu Tan, Bo Ma, Ruyi Wei, Cong Yu

Abstract: Vertical mixing disrupts the thermochemical equilibrium and introduces additional heat flux that alters exoplanetary atmospheric temperatures. We investigate how this mixing-induced heat flux affects atmospheric chemistry. Temperature increase in the lower atmosphere by the mixing-induced heat flux alters species abundances there and modifies those in the upper atmosphere through vertical transpor… ▽ More Vertical mixing disrupts the thermochemical equilibrium and introduces additional heat flux that alters exoplanetary atmospheric temperatures. We investigate how this mixing-induced heat flux affects atmospheric chemistry. Temperature increase in the lower atmosphere by the mixing-induced heat flux alters species abundances there and modifies those in the upper atmosphere through vertical transport. In the lower atmosphere, most species follow thermodynamic equilibrium with temperature changes. In the upper layers, species mixing ratios depend on the positions of quenching levels relative to the regions exhibiting significant mixing-induced temperature variations. When the quenching level resides within such region (e.g. CO, $\rm CH_4$, and $\rm H_2O$ with strong mixing), the mixing ratios in the upper atmosphere are modified due to changes in the quenched ratios affected by the temperature variation in the lower atmosphere. This alters the mixing ratio of other species (e.g. NO and $\rm CO_2$) through the chemical reaction network, whose quenching occurs in the region without much temperature change. The mixing ratios of $\rm CH_4$, $\rm H_2O$, and $\rm NH_3$ decrease in the lower atmosphere with increasing mixing heat flux, similarly reducing these ratios in the upper atmosphere. Conversely, the mixing ratios of CO, $\rm CO_2$, and NO rise in the lower atmosphere, with CO and $\rm CO_2$ also increasing in the upper levels, although NO decreases. Weaker host star irradiation lowers the overall temperature of the planet, allowing a smaller mixing to have a similar effect. We conclude that understanding the vertical mixing heat flux is essential for accurate atmospheric chemistry modeling and retrieval. △ Less

Submitted 24 October, 2025; originally announced October 2025.

Comments: 11 pages, 3 figures. APJ accepted

An On-Sky Atmospheric Calibration of SPT-SLIM

Authors: K. R. Dibert, M. Adamic, A. J. Anderson, P. S. Barry, B. A. Benson, C. S. Benson, E. Brooks, J. E. Carlstrom, T. Cecil, C. L. Chang, M. Dobbs, K. Fichman, K. S. Karkare, G. K. Keating, A. M. Lapuente, M. Lisovenko, D. P. Marrone, J. Montgomery, T. Natoli, Z. Pan, A. Rahlin, G. Robson, M. Rouble, G. Smecher, V. Yefremenko , et al. (4 additional authors not shown)

Abstract: We present the methodology and results of the on-sky responsivity calibration of the South Pole Telescope Shirokoff Line Intensity Mapper (SPT-SLIM). SPT-SLIM is a pathfinder line intensity mapping experiment utilizing the on-chip spectrometer technology, and was first deployed during the 2024-2025 Austral Summer season on the South Pole Telescope. During the two-week on-sky operation of SPT-SLIM,… ▽ More We present the methodology and results of the on-sky responsivity calibration of the South Pole Telescope Shirokoff Line Intensity Mapper (SPT-SLIM). SPT-SLIM is a pathfinder line intensity mapping experiment utilizing the on-chip spectrometer technology, and was first deployed during the 2024-2025 Austral Summer season on the South Pole Telescope. During the two-week on-sky operation of SPT-SLIM, we performed periodic measurements of the detector response as a function of the telescope elevation angle. Combining these data with atmospheric opacity measurements from an on-site atmospheric tipping radiometer, simulated South Pole atmospheric spectra, and measured detector spectral responses, we construct estimates for the responsivity of SPT-SLIM detectors to sky loading. We then use this model to calibrate observations of the moon taken by SPT-SLIM, cross-checking the result against the known brightness temperature of the Moon as a function of its phase. △ Less

Submitted 15 October, 2025; originally announced October 2025.

Comments: 7 pages, 7 figures, submitted to the 2025 International Workshop on Low Temperature Detectors (LTD 2025) proceedings

Design and Performance of the SPT-SLIM Receiver Cryostat

Authors: M. R. Young, M. Adamic, A. J. Anderson, P. S. Barry, B. A. Benson, C. S. Benson, E. Brooks, J. E. Carlstrom, T. Cecil, C. L. Chang, K. R. Dibert, M. Dobbs, K. Fichman, M. Hollister, K. S. Karkare, G. K. Keating, A. M. Lapuente, M. Lisovenko, D. P. Marrone, D. Mitchell, J. Montgomery, T. Natoli, Z. Pan, A. Rahlin, G. Robson , et al. (6 additional authors not shown)

Abstract: The South Pole Telescope Shirokoff Line Intensity Mapper (SPT-SLIM) is a millimeter-wavelength line-intensity mapping experiment, which was deployed on the South Pole Telescope (SPT) during the 2024-2025 Austral summer season. This pathfinder experiment serves to demonstrate the on-sky operation of multi-pixel on-chip spectrometer technology. We report on the cryogenic performance of the SPT-SLIM… ▽ More The South Pole Telescope Shirokoff Line Intensity Mapper (SPT-SLIM) is a millimeter-wavelength line-intensity mapping experiment, which was deployed on the South Pole Telescope (SPT) during the 2024-2025 Austral summer season. This pathfinder experiment serves to demonstrate the on-sky operation of multi-pixel on-chip spectrometer technology. We report on the cryogenic performance of the SPT-SLIM receiver for the first year of commissioning observations. The SPT-SLIM receiver utilizes an Adiabatic Demagnetization Refrigerator (ADR) for cooling the focal plane of superconducting filterbank spectrometers to a temperature of 150 mK. We demonstrate stable thermal performance of the focal plane module during observations consistent with thermal modeling, enabling a cryogenic operating efficiency above 80%. We also report on the receiver control system design utilizing the Observatory Control System (OCS) platform for automated cryogenic operation on the SPT. △ Less

Submitted 15 October, 2025; originally announced October 2025.

Comments: 6 pages, 6 figures, 1 table. Submitted to IEEE Transactions on Applied Superconductivity (Proceedings of the 21st International Conference on Low Temperature Detectors)

Improved Absolute Polarization Calibrator for BICEP CMB Polarimeters

Authors: A. R. Polish, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, H. Boenish, V. Buza, B. Cantrall, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, L. Duband, M. Echter, M. Eiben, B. D. Elwood, S. Fatigoni, J. P. Filippini, A. Fortes , et al. (67 additional authors not shown)

Abstract: Cosmic birefringence is a hypothesized parity violation in electromagnetism that predicts a frequency-independent polarization rotation as light propagates. This would rotate the light from the Cosmic Microwave Background, producing an unexpected EB correlation. However, cosmic birefringence angle is degenerate with instrument polarization angle, and breaking this degeneracy requires an absolute p… ▽ More Cosmic birefringence is a hypothesized parity violation in electromagnetism that predicts a frequency-independent polarization rotation as light propagates. This would rotate the light from the Cosmic Microwave Background, producing an unexpected EB correlation. However, cosmic birefringence angle is degenerate with instrument polarization angle, and breaking this degeneracy requires an absolute polarization calibration. We calibrate the BICEP3 telescope (a 95GHz CMB polarimeter) by observing a rotating polarized source (RPS) with both the telescope and a small test receiver called the In-Situ Absolute Angle Calibrator (ISAAC). △ Less

Submitted 14 October, 2025; originally announced October 2025.

Comments: As submitted to the proceedings of the mm Universe conference, 2025

BICEP/Keck XX: Component-separated maps of polarized CMB and thermal dust emission using Planck and BICEP/Keck Observations through the 2018 Observing Season

Authors: BICEP/Keck Collaboration, :, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, H. Boenish, V. Buza, B. Cantrall, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, L. Duband, M. Echter, M. Eiben, B. D. Elwood, S. Fatigoni, J. P. Filippini , et al. (73 additional authors not shown)

Abstract: We present component-separated polarization maps of the cosmic microwave background (CMB) and Galactic thermal dust emission, derived using data from the BICEP/Keck experiments through the 2018 observing season and Planck. By employing a maximum-likelihood method that utilizes observing matrices, we produce unbiased maps of the CMB and dust signals. We outline the computational challenges and demo… ▽ More We present component-separated polarization maps of the cosmic microwave background (CMB) and Galactic thermal dust emission, derived using data from the BICEP/Keck experiments through the 2018 observing season and Planck. By employing a maximum-likelihood method that utilizes observing matrices, we produce unbiased maps of the CMB and dust signals. We outline the computational challenges and demonstrate an efficient implementation of the component map estimator. We show methods to compute and characterize power spectra of these maps, opening up an alternative way to infer the tensor-to-scalar ratio from our data. We compare the results of this map-based separation method with the baseline BICEP/Keck analysis. Our analysis demonstrates consistency between the two methods, finding an 84% correlation between the pipelines. △ Less

Submitted 25 September, 2025; originally announced September 2025.

Comments: 16 pages, 20 figures, comments welcome

Integrated effect of the cosmic space magnetic field on the acceleration noise of the TQ gravitational wave detection program

Authors: Cheng-Long Yu, Jin Yan, Lin Ji, Wen-Ke Shi, Yi Zhang, Run-Qiu Liu, Hong-Qing Huo

Abstract: The TianQin(TQ) program is to deploy three satellites that can form an equilateral triangle in about 100,000 km Earth orbit to capture gravitational wave signals in the low-frequency band. In order to ensure accurate capture, noise needs to be analyzed and compensated. In this paper, we model and analyze the acceleration noise generated by the test mass affected by the magnetic field in space. In… ▽ More The TianQin(TQ) program is to deploy three satellites that can form an equilateral triangle in about 100,000 km Earth orbit to capture gravitational wave signals in the low-frequency band. In order to ensure accurate capture, noise needs to be analyzed and compensated. In this paper, we model and analyze the acceleration noise generated by the test mass affected by the magnetic field in space. In this paper, we use the Tsyganenko model as the background magnetic field of the TQ orbit, calculate the magnetic field and magnetic field gradient of the satellite orbit from 1997 to 2023, analyze the acceleration noise due to the coupling of the residual magnetic moment, the induced magnetic moment with the magnetic field in space and the acceleration noise due to the Lorentz force, and calculate the acceleration integrated noise of the influence of the magnetic field on the test mass from the power spectral densities of the modeled magnetic field and the magnetic field gradient. The acceleration integrated noise of the magnetic field influence on the test mass is calculated from the power spectral density of the magnetic field and the magnetic field gradient obtained by the model. Through the simulation study, the acceleration of the test mass induced by the magnetic field in the space of the TQ orbit reaches the magnitude of $10^{-16}ms^{-1}Hz^{-1/2}$, which is an important source of the influencing noise. The acceleration noise induced by the magnetic field and the Lorentz force is relatively higher than that induced by the magnetic field gradient. △ Less

Submitted 3 September, 2025; originally announced September 2025.

Spectral characterization and performance of SPT-SLIM on-chip filterbank spectrometers

Authors: C. S. Benson, K. Fichman, M. Adamic, A. J. Anderson, P. S. Barry, B. A. Benson, E. Brooks, J. E. Carlstrom, T. Cecil, C. L. Chang, K. R. Dibert, M. Dobbs, K. S. Karkare, G. K. Keating, A. M. Lapuente, M. Lisovenko, D. P. Marrone, J. Montgomery, T. Natoli, Z. Pan, A. Rahlin, G. Robson, M. Rouble, G. Smecher, V. Yefremenko , et al. (4 additional authors not shown)

Abstract: The South Pole Telescope Shirokoff Line Intensity Mapper (SPT-SLIM) experiment is a pathfinder for demonstrating the use of on-chip spectrometers for millimeter Line Intensity Mapping. We present spectral bandpass measurements of the SLIM spectrometer channels made on site using a Fourier Transform Spectrometer during SPT-SLIMs first deployment the 2024-2025 austral summer observing season. Throug… ▽ More The South Pole Telescope Shirokoff Line Intensity Mapper (SPT-SLIM) experiment is a pathfinder for demonstrating the use of on-chip spectrometers for millimeter Line Intensity Mapping. We present spectral bandpass measurements of the SLIM spectrometer channels made on site using a Fourier Transform Spectrometer during SPT-SLIMs first deployment the 2024-2025 austral summer observing season. Through this we demonstrate a technique for measuring the narrow band passes of the SPT-SLIM filterbanks that improves beyond the intrinsic resolution of a Fourier Transform Spectrometer. △ Less

Submitted 8 October, 2025; v1 submitted 2 September, 2025; originally announced September 2025.

Demonstration of a 1820 channel multiplexer for transition-edge sensor bolometers

Authors: J. C. Groh, Z. Ahmed, J. Austermann, J. Beall, D. Daniel, S. M. Duff, S. W. Henderson, J. Hubmayr, R. Lew, M. Link, T. J. Lucas, J. A. B. Mates, M. Silva-Feaver, R. Singh, J. Ullom, L. Vale, J. Van Lanen, M. Vissers, C. Yu

Abstract: The scalability of most transition-edge sensor arrays is limited by the multiplexing technology which combines their signals over a reduced number of wires and amplifiers. In this Letter, we present and demonstrate a multiplexer design optimized for transition-edge sensor bolometers with 1820 sensors per readout unit, a factor of two more than the previous state-of-the-art. The design is optimized… ▽ More The scalability of most transition-edge sensor arrays is limited by the multiplexing technology which combines their signals over a reduced number of wires and amplifiers. In this Letter, we present and demonstrate a multiplexer design optimized for transition-edge sensor bolometers with 1820 sensors per readout unit, a factor of two more than the previous state-of-the-art. The design is optimized for cosmic microwave background imaging applications, and it builds on previous microwave superconducting quantum interference device multiplexers by doubling the available readout bandwidth to the full 4-8 GHz octave. Evaluating the key performance metrics of yield, sensitivity, and crosstalk through laboratory testing, we find an end-to-end operable detector yield of 78%, a typical nearest-neighbor crosstalk amplitude of ~0.4%, and a median white noise level of 83 pA/rtHz due to the multiplexer, corresponding to an estimated contribution of 4% to the total system noise for a ground-based cosmic microwave background telescope. Additionally, we identify a possible path toward reducing resonator loss for future designs with reduced noise. We expect these developments to alleviate the system complexity, cryogenic requirements, and cost of future large arrays of low temperature detectors. △ Less

Submitted 17 October, 2025; v1 submitted 14 July, 2025; originally announced July 2025.

Journal ref: Appl. Phys. Lett. 127, 152602 (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

Exoplanet Ephemerides Change Observations (ExoEcho). II. Transit timing variation analysis of Brown Dwarfs around Solar-type Stars

Authors: Wenqin Wang, Xinyue Ma, Zhangliang Chen, Cong Yu, Shangfei Liu, Bo Ma

Abstract: Transit timing variation (TTV) is a useful tool for studying the orbital properties of transiting objects. However, few TTV studies have been done on transiting brown dwarfs (BDs) around solar-type stars. Here we study the long-term TTV of a population of close BD companions around solar-type stars using TESS data. We use the measured orbital period change rate to constrain the tidal interaction s… ▽ More Transit timing variation (TTV) is a useful tool for studying the orbital properties of transiting objects. However, few TTV studies have been done on transiting brown dwarfs (BDs) around solar-type stars. Here we study the long-term TTV of a population of close BD companions around solar-type stars using TESS data. We use the measured orbital period change rate to constrain the tidal interaction strength between the host star and the BD companion and put limits on the destruction timescale of these transiting BDs. However, we find no statistically significant evidence of orbital decay or expansion in our sample based on the current data. This may be due to either poor observational data or inherently weak tidal dissipation. We then perform simulations to investigate future observation strategies for detecting orbital decay of transiting BDs, which show NGTS-7A b, TOI-263~b and LP 261-75 b are the most promising targets in the next few years. Our study demonstrates the potential of TTV technique to probe the formation and evolution of close BD companions around solar-type stars. △ Less

Submitted 27 May, 2025; originally announced May 2025.

Comments: 13 pages, 8 figures, 4 tables. Accepted by ApJ

Dust Growth in ALMA Rings: II. Dusty Rossby Wave Instability

Authors: Can Cui, Konstantin Gerbig, Ya-Ping Li, Ziyan Xu, Rixin Li, Cong Yu, Min-Kai Lin, Feng Yuan

Abstract: Annular substructures serve as ideal venues for planetesimal formation. In this series, we investigate the linear stage of dust growth within rings. The first paper examines the global streaming instability, while this study focuses on the dusty Rossby wave instability (DRWI). We perform a linear analysis of the two-fluid equations on a background pressure bump, representing annular substructures.… ▽ More Annular substructures serve as ideal venues for planetesimal formation. In this series, we investigate the linear stage of dust growth within rings. The first paper examines the global streaming instability, while this study focuses on the dusty Rossby wave instability (DRWI). We perform a linear analysis of the two-fluid equations on a background pressure bump, representing annular substructures. The spectral code \textsc{Dedalus} is used to solve the linear eigenvalue problem. We identify two distinct DRWI modes: Type I, which originates from dust-modified gas RWI, and Type II, which results from dust-gas coupling. These modes never coexist for a given azimuthal wavenumber $\ky$, but transition between each other as $\ky$ varies. Type I modes are driven by the advection of background vorticity, whereas Type II modes involve two primary waves: Rossby waves, driven by advection, and thin waves, driven by dust-gas drag. Finally, we assess the relevance of DRWI in ALMA rings using DSHARP sources. Our findings suggest that Type I modes could explain the absence of azimuthal asymmetries in many ALMA disks, whereas Type II modes are entirely absent in all eight observed rings, implying that unresolved narrow rings or alternative mechanisms may play a role in dust growth within annular substructures. △ Less

Submitted 30 April, 2025; v1 submitted 7 April, 2025; originally announced April 2025.

Comments: 24 pages, 15 figures, accepted to ApJ, DOI: 10.3847/1538-4357/add146

Irradiated Atmospheres III : Radiative-Convective-Mixing Equilibrium for Non-Grey Picket-Fence Model

Authors: Wei Zhong, Zhen-Tai Zhang, Bo Ma, Xianyu Tan, Dong-Dong Ni, Cong Yu

Abstract: The non-grey picket-fence model predicts more accurately the temperatures in low-density regions compared to semi-grey models. This study investigates how the vertical mixing and convection fluxes modify the picket-fence model. The usual radiative-convective-equilibrium (RCE) is now extended to radiative-convective-mixing-equilibrium (RCME). The temperature profile, characterized by an increase wi… ▽ More The non-grey picket-fence model predicts more accurately the temperatures in low-density regions compared to semi-grey models. This study investigates how the vertical mixing and convection fluxes modify the picket-fence model. The usual radiative-convective-equilibrium (RCE) is now extended to radiative-convective-mixing-equilibrium (RCME). The temperature profile, characterized by an increase with pressure in the upper region and an inversion in the lower, is influenced by Rosseland opacity, spectral bands, and chemical composition. The atmosphere consists of five distinct layers: a pseudo-adiabatic zone shaped by mixing flux, two convective layers driven by convective flux with a smaller adiabatic gradient, and two radiative layers. In scenarios with lower Rosseland opacity, vertical mixing significantly reduces the width of temperature inversion, counteracting the cooling effect of the convective layers and driving the deep convective layer inward. The convective flux lowers the upper temperature and expands the upper convective layer. In the low-Rosseland-opacity five-band model, these fluxes significantly cool the mid-atmosphere when temperature increases with pressure, enlarging the pseudo-adiabatic region. Without TiO/VO, the pseudo-adiabatic region shrinks, indicating that TiO/VO enhances the mixing effect. Moreover, less mixing intensity is essential to maintain a stable five-layer structure. Therefore, future studies of chemical equilibrium with multi-frequency atmospheric opacity should clearly define the constraints on vertical mixing. △ Less

Submitted 27 March, 2025; originally announced March 2025.

Comments: 15 pages, 7 figures, ApJ accepted

Irradiated Atmospheres II: Interplay Between Scattering and Vertical-Mixing induced Energy Transport

Authors: Zhen-Tai Zhang, Wei Zhong, Xianyu Tan, Bo Ma, Ruyi Wei, Cong Yu

Abstract: The scattering is crucial for the atmospheric thermal profiles. The energy transport by the vertical mixing plays an essential role for the greenhouse or anti-greenhouse effect. This work explores the interaction between scattering and vertical mixing, specifically whether these processes enhance or mitigate each other's effects on atmospheric temperature. The interaction between mixing flux and s… ▽ More The scattering is crucial for the atmospheric thermal profiles. The energy transport by the vertical mixing plays an essential role for the greenhouse or anti-greenhouse effect. This work explores the interaction between scattering and vertical mixing, specifically whether these processes enhance or mitigate each other's effects on atmospheric temperature. The interaction between mixing flux and scattering is nonlinear. Our calculations indicate that thermal scattering intensifies the greenhouse effects caused by vertical mixing in the middle atmosphere but reduces it in the lower layers. In the middle atmosphere, increased vertical mixing enhances the warming effect of the thermal scattering while diminishing the cooling effect of visible scattering. In the lower atmosphere, it enhances the anti-greenhouse effect linked to visible scattering and diminishes the greenhouse effect produced by thermal scattering. The combined influence of thermal scattering and vertical mixing on the lower atmosphere's greenhouse effect is weaker than their separate impacts, akin to $1+1<2$. It is also interesting to note that the joint effect may also influence chemistry and cloud formation, altering the thermal structure. △ Less

Submitted 24 March, 2025; originally announced March 2025.

Comments: 13 pages, 7 figures. APJ accepted

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

Solving Online Resource-Constrained Scheduling for Follow-Up Observation in Astronomy: a Reinforcement Learning Approach

Authors: Yajie Zhang, Ce Yu, Chao Sun, Jizeng Wei, Junhan Ju, Shanjiang Tang

Abstract: In the astronomical observation field, determining the allocation of observation resources of the telescope array and planning follow-up observations for targets of opportunity (ToOs) are indispensable components of astronomical scientific discovery. This problem is computationally challenging, given the online observation setting and the abundance of time-varying factors that can affect whether a… ▽ More In the astronomical observation field, determining the allocation of observation resources of the telescope array and planning follow-up observations for targets of opportunity (ToOs) are indispensable components of astronomical scientific discovery. This problem is computationally challenging, given the online observation setting and the abundance of time-varying factors that can affect whether an observation can be conducted. This paper presents ROARS, a reinforcement learning approach for online astronomical resource-constrained scheduling. To capture the structure of the astronomical observation scheduling, we depict every schedule using a directed acyclic graph (DAG), illustrating the dependency of timing between different observation tasks within the schedule. Deep reinforcement learning is used to learn a policy that can improve the feasible solution by iteratively local rewriting until convergence. It can solve the challenge of obtaining a complete solution directly from scratch in astronomical observation scenarios, due to the high computational complexity resulting from numerous spatial and temporal constraints. A simulation environment is developed based on real-world scenarios for experiments, to evaluate the effectiveness of our proposed scheduling approach. The experimental results show that ROARS surpasses 5 popular heuristics, adapts to various observation scenarios and learns effective strategies with hindsight. △ Less

Submitted 16 February, 2025; originally announced February 2025.

Sun-as-a-star analysis of simulated solar flares

Authors: H. C. Yu, J. Hong, M. D. Ding

Abstract: Context: Stellar flares have an impact on habitable planets. To relate the observations of the Sun with those of stars, one needs to use a Sun-as-a-star analysis, that is, to degrade the resolution of the Sun to a single point. With the data of the Sun-as-a-star observations, a simulation of solar flares is required to provide a systemic clue for the Sun-as-a-star study. Aims: We aim to explore… ▽ More Context: Stellar flares have an impact on habitable planets. To relate the observations of the Sun with those of stars, one needs to use a Sun-as-a-star analysis, that is, to degrade the resolution of the Sun to a single point. With the data of the Sun-as-a-star observations, a simulation of solar flares is required to provide a systemic clue for the Sun-as-a-star study. Aims: We aim to explore how the Sun-as-a-star spectrum varies with the flare magnitude and location based on a grid of solar flare models. Methods: Using 1D radiative hydrodynamics modeling and multi-thread flare assumption, we obtained the spectrum of a typical flare with an enhancement of chromospheric lines. Result: The Sun-as-a-star spectrum of the H$α$ line shows enhanced and shifted components, which are highly dependent on the flare magnitude and location. The equivalent width $Δ\mathrm{EW}$ is a good indicator of energy release. The bisector method can be used to diagnose the sign of the line-of-sight velocity in the flaring atmosphere. For both H$α$ and H$β$ lines, the Sun-as-a-star spectrum of a limb flare tends to be wider and shows a dip in the line center. In particular, we propose two quantities to diagnose the magnitude and location of the stellar flares. Besides this, caution must be taken when calculating the radiation energy, since the astrophysical flux-to-energy conversion ratio is dependent on the flare location. △ Less

Submitted 1 February, 2025; originally announced February 2025.

Comments: 14 pages, 20 figures

Exoplanet Ephemerides Change Observations (ExoEcho). I. Transit Timing Analysis of Thirty-Seven Exoplanets using HST/WFC3 Data

Authors: Xinyue Ma, Wenqin Wang, Zixin Zhang, Cong Yu, Dichang Chen, Jiwei Xie, Shangfei Liu, Li Zhou, Bo Ma

Abstract: The ExoEcho project is designed to study the photodynamics of exoplanets by leveraging high-precision transit timing data from ground- and space-based telescopes. Some exoplanets are experiencing orbital decay, and transit timing variation (TTV) is a useful technique to study their orbital period variations. In this study, we have obtained transit middle-time data from the Hubble Space Telescope (… ▽ More The ExoEcho project is designed to study the photodynamics of exoplanets by leveraging high-precision transit timing data from ground- and space-based telescopes. Some exoplanets are experiencing orbital decay, and transit timing variation (TTV) is a useful technique to study their orbital period variations. In this study, we have obtained transit middle-time data from the Hubble Space Telescope (HST) observations for 37 short-period exoplanets, most of which are hot Jupiters. To search for potential long- and short-term orbital period variations within the sample, we conduct TTV model fitting using both linear and quadratic ephemeris models. Our analysis identifies two hot Jupiters experiencing strong periodic decays. Given the old age of the host stars of the hot Jupiter population, our findings call for a scenario where HJs are continuously being destructed and created. Our study demonstrates the importance of incorporating high-precision transit timing data to TTV study in the future. △ Less

Submitted 9 January, 2025; originally announced January 2025.

Superradiance in acoustic black hole

Authors: Chengye Yu, Xiaolin Zhang, Sobhan Kazempour, Sichun Sun

Abstract: Rotating superradiance in cylinders has recently been observed experimentally using acoustic waves to shed light on the understanding of the superradiant phenomenon in black holes. In this paper, for the first time, we study superradiance in acoustic black holes through theoretical analysis and numerical simulation using COMSOL multiphysics. We find that superradiance can occur in acoustic black h… ▽ More Rotating superradiance in cylinders has recently been observed experimentally using acoustic waves to shed light on the understanding of the superradiant phenomenon in black holes. In this paper, for the first time, we study superradiance in acoustic black holes through theoretical analysis and numerical simulation using COMSOL multiphysics. We find that superradiance can occur in acoustic black holes when the general superradiance condition is met. We also find the amplification effect is significantly weaker in acoustic black holes than in regular cylinders, due to the absorption in such structure. △ Less

Submitted 30 December, 2024; originally announced December 2024.

Comments: 6 pages, 9 figures

Streaming Torque with Turbulent Diffusion

Authors: Qiang Hou, Cong Yu

Abstract: Fast type-I migration of (proto)planets poses a challenging problem for the core accretion formation scenario. We found that the dust-induced ``Streaming Torque (ST)'' may slow down or even reverse the planet migration in \cite{Hou2024}. But in realistic protoplanetary disks, dust diffusion induced by gas turbulence may have important influences on ST. We perform linear analysis to investigate the… ▽ More Fast type-I migration of (proto)planets poses a challenging problem for the core accretion formation scenario. We found that the dust-induced ``Streaming Torque (ST)'' may slow down or even reverse the planet migration in \cite{Hou2024}. But in realistic protoplanetary disks, dust diffusion induced by gas turbulence may have important influences on ST. We perform linear analysis to investigate the effects of dust diffusion on ST. The dependence of ST on the dust diffusion may provide better constraints on the turbulence strength and the stopping time $τ$. We derive the dispersion relation for all the wave modes in the two-fluid system. The dust diffusion will smooth the short-wavelength structure of the the quasi-drift mode and split it into two predominant D-drift modes with opposite directions. The outgoing D-drift mode will contribute to a negative torque on planets, particularly when $τ\sim 0.1$, which slightly shifts the zero-torque turning point. We explore how ST depends on the regimes of aerodynamic drag, dust mass fraction and disk scale height. We compare the radial wavenumbers of D-drift modes under different formulations of dust diffusion and find qualitative agreement. In all cases, $τ$ at the zero-torque turning point, which determines the direction of planetary migration, consistently remains on the order of $\sim 0.1$, corresponding to large pebble-sized dust grains. This suggests that rapid dust coagulation can inhibit the inward migration of planets, implying that weak gas turbulence may enhance the survival of protoplanets. △ Less

Submitted 17 December, 2024; originally announced December 2024.

Comments: Accepted for publication in ApJ

Vortex-Induced Rings and Gaps within Protoplanetary Disks

Authors: Xiaoyi Ma, Pinghui Huang, Cong Yu, Ruobing Dong

Abstract: Observations of protoplanetary disks have revealed the presence of both crescent-shaped and ring-like structures in dust continuum emission. These crescents are thought to arise from dust-trapping vortices generated by the Rossby Wave Instability (RWI), which induces density waves akin to those caused by planets. These vortices have the potential to create gaps and rings within the disk, resulting… ▽ More Observations of protoplanetary disks have revealed the presence of both crescent-shaped and ring-like structures in dust continuum emission. These crescents are thought to arise from dust-trapping vortices generated by the Rossby Wave Instability (RWI), which induces density waves akin to those caused by planets. These vortices have the potential to create gaps and rings within the disk, resulting from the dissipation of their density waves. We carry out 2D hydrodynamic simulations in the shearing box to investigate vortex-disk interaction. We find that long-lived vortices can produce dust rings and gaps in inviscid discs detectable by ALMA, and a more elongated vortex produces rings at larger separations. Vortex-induced density waves carry over two orders of magnitude higher angular momentum flux compared to planet-induced ones that shock at the same location, making the former much more effective at producing dust gaps and rings far away. △ Less

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

Comments: 15 pages, 11 figures; Accepted to ApJ

Development of an MKID frequency-to-pixel LED mapper for SPT-3G+

Authors: E. S. Martsen, P. S. Barry, B. A. Benson, K. R. Dibert, K. N. Fichman, T. Natoli, M. Rouble, C. Yu

Abstract: SPT-3G+ is the next-generation camera for the South Pole Telescope (SPT). SPT is designed to measure the cosmic microwave background (CMB) and the mm/sub-mm sky. The planned focal plane consists of 34,000 microwave kinetic inductance detectors (MKIDs), divided among three observing bands centered at 220, 285, and 345 GHz. Each readout line is designed to measure 800 MKIDs over a 500 MHz bandwidth,… ▽ More SPT-3G+ is the next-generation camera for the South Pole Telescope (SPT). SPT is designed to measure the cosmic microwave background (CMB) and the mm/sub-mm sky. The planned focal plane consists of 34,000 microwave kinetic inductance detectors (MKIDs), divided among three observing bands centered at 220, 285, and 345 GHz. Each readout line is designed to measure 800 MKIDs over a 500 MHz bandwidth, which places stringent constraints on the accuracy of the frequency placement required to limit resonator collisions that reduce the overall detector yield. To meet this constraint, we are developing a two-step process that first optically maps the resonance to a physical pixel location, and then next trims the interdigitated capacitor (IDC) to adjust the resonator frequency. We present a cryogenic LED apparatus operable at 300 mK for the optical illumination of SPT-3G+ detector arrays. We demonstrate integration of the LED controls with the GHz readout electronics (RF-ICE) to take data on an array of prototype SPT-3G+ detectors. We show that this technique is useful for characterizing defects in the resonator frequency across the detector array and will allow for improvements in the detector yield. △ Less

Submitted 21 March, 2025; v1 submitted 26 November, 2024; originally announced November 2024.

Comments: 5 pages, 10 figures, Applied Superconductivity Conference (ASC 2024) proceedings, Accepted for publication in the ASC 2024 Special Issue of the IEEE Transactions on Applied Superconductivity (IEEE TAS)( Volume: 35, Issue: 5, pp: 1-4, Art no: 2500104, August 2025)

Irradiated Atmospheres I: Heating by Vertical-Mixing Induced Energy Transport

Authors: Wei Zhong, Zhen-Tai Zhang, Hui-Sheng Zhong, Bo Ma, Xianyu Tan, Cong Yu

Abstract: Observations have revealed unique temperature profiles in hot Jupiter atmospheres. We propose that the energy transport by vertical mixing could lead to such thermal features. In our new scenario, strong absorbers, TiO and VO are not necessary. Vertical mixing could be naturally excited by atmospheric circulation or internal gravity wave breaking. We perform radiative transfer calculations by taki… ▽ More Observations have revealed unique temperature profiles in hot Jupiter atmospheres. We propose that the energy transport by vertical mixing could lead to such thermal features. In our new scenario, strong absorbers, TiO and VO are not necessary. Vertical mixing could be naturally excited by atmospheric circulation or internal gravity wave breaking. We perform radiative transfer calculations by taking into account the vertical mixing driven energy transport. The radiative equilibrium (RE) is replaced by radiative-mixing equilibrium (RME). We investigate how the mixing strength, $K_{\rm zz}$, affects the atmospheric temperature-pressure profile. Strong mixing can heat the lower atmosphere and cool the upper atmosphere. This effect has important effects on the atmosphere thermal features that would form without mixing. In certain circumstances, it can induce temperature inversions in scenarios where the temperature monotonically increases with increasing pressure under conditions of lower thermal band opacity. Temperature inversions show up as $K_{\rm zz}$ increases with altitude due to shear interaction with the convection layer. The atmospheric thermal structure of HD~209458b can be well fitted with $K_{\rm zz} \propto (P/1\ {\rm bar})^{-1/2}\ {\rm cm}^{2} \ {\rm s}^{-1}$. Our findings suggest vertical mixing promotes temperature inversions and lowers $K_{\rm zz}$ estimates compared to prior studies. Incorporating chemical species into vertical mixing will significantly affect the thermal profile due to their temperature sensitivity. △ Less

Submitted 24 November, 2024; v1 submitted 19 November, 2024; originally announced November 2024.

Comments: 12 pages, 6 figure. Accepted in ApJ

BICEP/Keck XIX: Extremely Thin Composite Polymer Vacuum Windows for BICEP and Other High Throughput Millimeter Wave Telescopes

Authors: BICEP/Keck Collaboration, :, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, H. Boenish, V. Buza, K. Carter, J. R. Cheshire IV, J. Connors, J. Cornelison, L. Corrigan, M. Crumrine, S. Crystian, A. J. Cukierman, E. Denison, L. Duband, M. Echter, M. Eiben, B. D. Elwood , et al. (69 additional authors not shown)

Abstract: Millimeter-wave refracting telescopes targeting the degree-scale structure of the cosmic microwave background (CMB) have recently grown to diffraction-limited apertures of over 0.5 meters. These instruments are entirely housed in vacuum cryostats to support their sub-kelvin bolometric detectors and to minimize radiative loading from thermal emission due to absorption loss in their transmissive opt… ▽ More Millimeter-wave refracting telescopes targeting the degree-scale structure of the cosmic microwave background (CMB) have recently grown to diffraction-limited apertures of over 0.5 meters. These instruments are entirely housed in vacuum cryostats to support their sub-kelvin bolometric detectors and to minimize radiative loading from thermal emission due to absorption loss in their transmissive optical elements. The large vacuum window is the only optical element in the system at ambient temperature, and therefore minimizing loss in the window is crucial for maximizing detector sensitivity. This motivates the use of low-loss polymer materials and a window as thin as practicable. However, the window must simultaneously meet the requirement to keep sufficient vacuum, and therefore must limit gas permeation and remain mechanically robust against catastrophic failure under pressure. We report on the development of extremely thin composite polyethylene window technology that meets these goals. Two windows have been deployed for two full observing seasons on the BICEP3 and BA150 CMB telescopes at the South Pole. On BICEP3, the window has demonstrated a 6% improvement in detector sensitivity. △ Less

Submitted 15 November, 2024; originally announced November 2024.

Comments: 20 pages, 12 figures, 4 tables

Cosmology of Quasi-Dilaton Massive Gravity with Non-minimal Kinetic Coupling

Authors: Sobhan Kazempour, Amin Rezaei Akbarieh, Sichun Sun, Chengye Yu

Abstract: In this study, we introduce an extension of the quasi-dilaton massive gravity theory and derive the field equations by varying the action with respect to the metric. This extension elucidates the dynamics of the system and demonstrates how it can encompass and recover previous cosmological models through different parameter values. We present the cosmological background equations to analyze self-a… ▽ More In this study, we introduce an extension of the quasi-dilaton massive gravity theory and derive the field equations by varying the action with respect to the metric. This extension elucidates the dynamics of the system and demonstrates how it can encompass and recover previous cosmological models through different parameter values. We present the cosmological background equations to analyze self-accelerating solutions that can explain the late-time accelerated expansion of the Universe, driven by an effective cosmological constant arising from massive gravity. Besides, we apply the quasi-dilaton massive gravity theory with non-minimal kinetic coupling to a Type Ia Supernovae (SNIa) data set to test its viability. Our findings indicate that the theory is able to account for the observed acceleration of the expansion of the universe without invoking dark energy. In addition, we carry out a comprehensive perturbation analysis examining tensor, vector, and scalar perturbations independently. We derive the dispersion relation of gravitational waves in a Friedman-Lemaitre-Robertson-Walker (FLRW) cosmology and determine the stability conditions of the system. Such an analysis results in a sharper quasi-dilaton massive gravity theory with non-minimal kinetic coupling by ensuring the stability conditions of the system are maintained and that strong constraints on theory parameters are provided. △ Less

Submitted 25 May, 2025; v1 submitted 23 October, 2024; originally announced October 2024.

Journal ref: Nuclear Physics B, Volume 1017, August 2025, 116952

BICEP/Keck XVIII: Measurement of BICEP3 polarization angles and consequences for constraining cosmic birefringence and inflation

Authors: BICEP/Keck Collaboration, :, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, H. Boenish, V. Buza, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, L. Duband, M. Eiben, B. D. Elwood, S. Fatigoni, J. P. Filippini, A. Fortes, M. Gao , et al. (62 additional authors not shown)

Abstract: We use a custom-made calibrator to measure individual detectors' polarization angles of BICEP3, a small aperture telescope observing the cosmic microwave background (CMB) at 95GHz from the South Pole. We describe our calibration strategy and the statistical and systematic uncertainties associated with the measurement. We reach an unprecedented precision for such measurement on a CMB experiment, wi… ▽ More We use a custom-made calibrator to measure individual detectors' polarization angles of BICEP3, a small aperture telescope observing the cosmic microwave background (CMB) at 95GHz from the South Pole. We describe our calibration strategy and the statistical and systematic uncertainties associated with the measurement. We reach an unprecedented precision for such measurement on a CMB experiment, with a repeatability for each detector pair of $0.02°$. We show that the relative angles measured using this method are in excellent agreement with those extracted from CMB data. Because the absolute measurement is currently limited by a systematic uncertainty, we do not derive cosmic birefringence constraints from BICEP3 data in this work. Rather, we forecast the sensitivity of BICEP3 sky maps for such analysis. We investigate the relative contributions of instrument noise, lensing, and dust, as well as astrophysical and instrumental systematics. We also explore the constraining power of different angle estimators, depending on analysis choices. We establish that the BICEP3 2-year dataset (2017--2018) has an on-sky sensitivity to the cosmic birefringence angle of $σ= 0.078°$, which could be improved to $σ= 0.055°$ by adding all of the existing BICEP3 data (through 2023). Furthermore, we emphasize the possibility of using the BICEP3 sky patch as a polarization calibration source for CMB experiments, which with the present data could reach a precision of $0.035°$. Finally, in the context of inflation searches, we investigate the impact of detector-to-detector variations in polarization angles as they may bias the tensor-to-scalar ratio r. We show that while the effect is expected to remain subdominant to other sources of systematic uncertainty, it can be reliably calibrated using polarization angle measurements such as the ones we present in this paper. △ Less

Submitted 17 February, 2025; v1 submitted 15 October, 2024; originally announced October 2024.

Comments: 29 Pages, 17 Figures, 6 Tables, as submitted to PRD. Visit bicepkeck.org for figure pdfs/pngs

GRRIS: a real-time intra-site observation scheduling scheme for distributed survey telescope arrays

Authors: Yajie Zhang, Ce Yu, Chao Sun, Yi Hu, Zhaohui Shang, Jizeng Wei, Xu Yang

Abstract: The distributed telescope array offers promise for conducting large-sky-area, high-frequency time domain surveys. Multiple telescopes can be deployed at each observation site, so intra-site observation task scheduling is crucial for enhancing observation efficiency and quality. Efficient use of observable time and rapid response to special situations are critical to maximize scientific discovery i… ▽ More The distributed telescope array offers promise for conducting large-sky-area, high-frequency time domain surveys. Multiple telescopes can be deployed at each observation site, so intra-site observation task scheduling is crucial for enhancing observation efficiency and quality. Efficient use of observable time and rapid response to special situations are critical to maximize scientific discovery in time domain surveys. Besides, the competing scientific priorities, time-varying observation conditions, and capabilities of observation equipment, lead to a vast search space of the scheduling. So with the increasing number of telescopes and observation fields, balancing computational time with solution quality in observation scheduling poses a significant challenge. Informed by the seminal contributions of earlier studies on a multilevel scheduling model and global scheduler for time domain telescope array, this study is devoted to further exploring the site scheduler. Formulating the observation scheduling of multiple telescopes at the site as a cooperative decision-making problem, this paper proposes GRRIS, a real-time intra-site observation scheduling scheme for telescope array using graph and reinforcement learning. It employs a graph neural network to learn node features that can embed the spatial structure of the observation scheduling. An algorithm based on multi-agent reinforcement learning is designed to efficiently learn the optimum allocation policy of telescope agents to field nodes. Through numerical simulations with real-world scenarios, GRRIS can achieve up to a 22% solution improvement over the most competitive scheme. It offers better scalability and sub-second decision speed, meeting the needs of observation scheduling control for future distributed telescope arrays. △ Less

Submitted 19 October, 2024; v1 submitted 13 October, 2024; originally announced October 2024.

Comments: Astronomical Journal

Journal ref: AJ 168 214 (2024)

Constraining the Presence of Companion Planets in Hot Jupiter Planetary System Using TTV Observation from TESS

Authors: Zixin Zhang, Wenqin Wang, Xinyue Ma, Zhangliang Chen, Yonghao Wang, Cong Yu, Shangfei Liu, Yang Gao, Baitian Tang, Bo Ma

Abstract: The presence of another planetary companion in a transiting exoplanet system can impact its transit light curve, leading to sinusoidal transit timing variations (TTV). By utilizing both $χ^2$ and RMS analysis, we have combined the TESS observation data with an N-body simulation to investigate the existence of an additional planet in the system and put a limit on its mass. We have developed CMAT, a… ▽ More The presence of another planetary companion in a transiting exoplanet system can impact its transit light curve, leading to sinusoidal transit timing variations (TTV). By utilizing both $χ^2$ and RMS analysis, we have combined the TESS observation data with an N-body simulation to investigate the existence of an additional planet in the system and put a limit on its mass. We have developed CMAT, an efficient and user-friendly tool for fitting transit light curves and calculating TTV with a theoretical period, based on which we can give a limit on its hidden companion's mass. We use 260 hot Jupiter systems from the complete TESS data set to demonstrate the use of CMAT. Our findings indicate that, for most systems, the upper mass limit of a companion planet can be restricted to several Jupiter masses. This constraint becomes stronger near resonance orbits, such as the 1:2, 2:1, 3:1, and 4:1 mean motion resonance, where the limit is reduced to several Earth masses. These findings align with previous studies suggesting that a lack of companion planets with resonance in hot Jupiter systems could potentially support the high eccentricity migration theory. Additionally, we observed that the choice between $χ^2$ or {root mean square (RMS)} method does not significantly affect the upper limit on companion mass; however, $χ^2$ analysis may result in weaker restrictions but is statistically more robust compared to RMS analysis in most cases. △ Less

Submitted 3 October, 2024; originally announced October 2024.

Comments: Accepted for publication in ApJS

Calibration Measurements of the BICEP3 and BICEP Array CMB Polarimeters from 2017 to 2024

Authors: Christos Giannakopoulos, Clara Vergès, P. A. R. Ade, Zeeshan Ahmed, Mandana Amiri, Denis Barkats, Ritoban Basu Thakur, Colin A. Bischoff, Dominic Beck, James J. Bock, Hans Boenish, Victor Buza, James R. Cheshire IV, Jake Connors, James Cornelison, Michael Crumrine, Ari Jozef Cukierman, Edward Denison, Marion Dierickx, Lionel Duband, Miranda Eiben, Brodi D. Elwood, Sofia Fatigoni, Jeff P. Filippini, Antonio Fortes , et al. (61 additional authors not shown)

Abstract: The BICEP3 and BICEP Array polarimeters are small-aperture refracting telescopes located at the South Pole designed to measure primordial gravitational wave signatures in the Cosmic Microwave Background (CMB) polarization, predicted by inflation. Constraining the inflationary signal requires not only excellent sensitivity, but also careful control of instrumental systematics. Both instruments use… ▽ More The BICEP3 and BICEP Array polarimeters are small-aperture refracting telescopes located at the South Pole designed to measure primordial gravitational wave signatures in the Cosmic Microwave Background (CMB) polarization, predicted by inflation. Constraining the inflationary signal requires not only excellent sensitivity, but also careful control of instrumental systematics. Both instruments use antenna-coupled orthogonally polarized detector pairs, and the polarized sky signal is reconstructed by taking the difference in each detector pair. As a result, the differential response between detectors within a pair becomes an important systematic effect we must control. Additionally, mapping the intensity and polarization response in regions away from the main beam can inform how sidelobe levels affect CMB measurements. Extensive calibration measurements are taken in situ every austral summer for control of instrumental systematics and instrument characterisation. In this work, we detail the set of beam calibration measurements that we conduct on the BICEP receivers, from deep measurements of main beam response to polarized beam response and sidelobe mapping. We discuss the impact of these measurements for instrumental systematics studies and design choices for future CMB receivers. △ Less

Submitted 24 September, 2024; originally announced September 2024.

Comments: 13 pages, 7 figures, 1 table, Proceedings paper SPIE 2024

Vertical Shear Instability with Partially Reflecting Boundary Conditions

Authors: Yuzi Wu, Cong Yu, Can Cui

Abstract: The vertical shear instability (VSI) is widely believed to be effective in driving turbulence in protoplanetary disks. Prior studies on VSI exclusively exploit the reflecting boundary conditions (BCs) at the disk surfaces. VSI depends critically on the boundary behaviors of waves at the disk surfaces. We extend earlier studies by performing a comprehensive numerical analysis of VSI with partially… ▽ More The vertical shear instability (VSI) is widely believed to be effective in driving turbulence in protoplanetary disks. Prior studies on VSI exclusively exploit the reflecting boundary conditions (BCs) at the disk surfaces. VSI depends critically on the boundary behaviors of waves at the disk surfaces. We extend earlier studies by performing a comprehensive numerical analysis of VSI with partially reflecting BCs for both the axisymmetric and non-axisymmetric unstable VSI modes. We find that the growth rates of the unstable modes diminish when the outgoing component of the flow is greater than the incoming one for high-order body modes. When the outgoing wave component dominates, the growth of VSI is notably suppressed. We find that the non-axisymmetric modes are unstable and they grow at a rate that decreases with the azimuthal wavenumber. The different BCs at the lower and upper disk surfaces naturally lead to non-symmetric modes relative to the disk midplane. The potential implications of our studies for further understanding planetary formation and evolution in protoplanetary disks (PPDs) are also briefly discussed. △ Less

Submitted 12 September, 2024; originally announced September 2024.

Comments: Accepted for publication in MNRAS

Development of the 220/270 GHz Receiver of BICEP Array

Authors: The BICEP/Keck Collaboration, :, Y. Nakato, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, V. Buza, B. Cantrall, J. R. Cheshire IV, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, M. Dierickx, L. Duband, M. Eiben, B. D. Elwood, S. Fatigoni, J. P. Filippini, A. Fortes , et al. (61 additional authors not shown)

Abstract: Measurements of B-mode polarization in the CMB sourced from primordial gravitational waves would provide information on the energy scale of inflation and its potential form. To achieve these goals, one must carefully characterize the Galactic foregrounds, which can be distinguished from the CMB by conducting measurements at multiple frequencies. BICEP Array is the latest-generation multi-frequency… ▽ More Measurements of B-mode polarization in the CMB sourced from primordial gravitational waves would provide information on the energy scale of inflation and its potential form. To achieve these goals, one must carefully characterize the Galactic foregrounds, which can be distinguished from the CMB by conducting measurements at multiple frequencies. BICEP Array is the latest-generation multi-frequency instrument of the BICEP/Keck program, which specifically targets degree-scale primordial B-modes in the CMB. In its final configuration, this telescope will consist of four small-aperture receivers, spanning frequency bands from 30 to 270 GHz. The 220/270 GHz receiver designed to characterize Galactic dust is currently undergoing commissioning at Stanford University and is scheduled to deploy to the South Pole during the 2024--2025 austral summer. Here, we will provide an overview of this high-frequency receiver and discuss the integration status and test results as it is being commissioned. △ Less

Submitted 3 September, 2024; originally announced September 2024.

Boundary Layers of Circumplanetary Disks around Spinning Planets II. Global Modes with Azimuthal Magnetic Fields

Authors: Zhihao Fu, Shunquan Huang, Cong Yu

Abstract: The accretion of material from disks onto weakly magnetized objects invariably involves its traversal through a material surface, known as the boundary layer (BL). Our prior studies have revealed two distinct global wave modes for circumplanetary disks (CPDs) with BLs exhibit opposite behaviors in spin modulation.We perform a detailed analysis about the effect of magnetic fields on these global mo… ▽ More The accretion of material from disks onto weakly magnetized objects invariably involves its traversal through a material surface, known as the boundary layer (BL). Our prior studies have revealed two distinct global wave modes for circumplanetary disks (CPDs) with BLs exhibit opposite behaviors in spin modulation.We perform a detailed analysis about the effect of magnetic fields on these global modes, highlighting how magnetic resonances and turning points could complicate the wave dynamics. The angular momentum flux becomes positive near the BL with increasing magnetic field strength. We also examine the perturbation profile to demonstrate the amplification of magnetic fields within the BL. The dependence of growth rates on the magnetic field strength, and the spin rate are systematically investigated. We find that stronger magnetic fields tend to result in lower terminal spin rates. We stress the potential possibility for the formation of angular momentum belts and pressure bumps. The implication for the spin evolution and quasi-period oscillations observed in compact objects are also briefly discussed. Our calculations advance the understanding of magnetohydrodynamical (MHD) accretion processes and lays a foundation for observational studies and numerical simulations. △ Less

Submitted 29 August, 2024; originally announced August 2024.

Comments: 20 pages, 13 figures, accepted for publication in the Astrophysical Journal (APJ)

A Series of (Net) Spin-down Glitches in PSR J1522-5735: Insights from the Vortex Creep and Vortex Bending Models

Authors: S. Q. Zhou, W. T. Ye, M. Y. Ge, E. GügercinoğLu, S. J. Zheng, C. Yu, J. P. Yuan, J. Zhang

Abstract: Through a detailed timing analysis of $\textit{Fermi}$-LAT data, the rotational behavior of the $γ$-ray pulsar PSR J1522$-$5735 was tracked from August 2008 (MJD 54692) to January 2024 (MJD 60320). During this 15.4-year period, two over-recovery glitches and four anti-glitches were identified, marking a rare occurrence in rotation-powered pulsars (RPPs). The magnitudes of these (net) spin-down gli… ▽ More Through a detailed timing analysis of $\textit{Fermi}$-LAT data, the rotational behavior of the $γ$-ray pulsar PSR J1522$-$5735 was tracked from August 2008 (MJD 54692) to January 2024 (MJD 60320). During this 15.4-year period, two over-recovery glitches and four anti-glitches were identified, marking a rare occurrence in rotation-powered pulsars (RPPs). The magnitudes of these (net) spin-down glitches were determined to be $|Δν_{\rm g}/ν| \sim 10^{-8}$, well above the estimated detectability limit. For the two over-recovery glitches, the respective recovery fractions $Q$ are $2.1(7)$ and $1.4(2)$. Further analysis showed no substantial variations in either the flux or pulse profile shape in any of these events, suggesting that small (net) spin-down glitches, unlike large events observed in magnetars and magnetar-like RPPs, may occur without leaving an impact on the magnetosphere. Within the framework of the vortex creep and vortex bending models, anti-glitches and over-recoveries indicate the recoupling of vortex lines that moved inward as a result of a crustquake; meanwhile, the apparent fluctuations in the spin-down rate after the glitches occur as a result of the coupling of the oscillations of bent vortex lines to the magnetosphere. △ Less

Submitted 11 December, 2024; v1 submitted 17 August, 2024; originally announced August 2024.

Comments: 8 pages, 3 figures, 2 tables, Accepted for Publication in ApJ. Comments Welcome!

Streaming Torque in Dust-Gas Coupled Protoplanetary Disks

Authors: Qiang Hou, Cong Yu

Abstract: We investigate the migration of low-mass protoplanets embedded in dust-gas coupled protoplanetary disks. Linear calculations are performed with respect to the NSH (Nakagawa-Sekiya-Hayashi 1986) equilibrium within a shearing sheet. We find that the dusty quasi-drift mode dominates the dynamical behaviors in close proximity to the protoplanet. This mode exhibits an extremely short radial wavelength,… ▽ More We investigate the migration of low-mass protoplanets embedded in dust-gas coupled protoplanetary disks. Linear calculations are performed with respect to the NSH (Nakagawa-Sekiya-Hayashi 1986) equilibrium within a shearing sheet. We find that the dusty quasi-drift mode dominates the dynamical behaviors in close proximity to the protoplanet. This mode exhibits an extremely short radial wavelength, characterized by a dispersion relation of $ \tildeω = \left( 1 + μ\right) \boldsymbol{W}_s \cdot \boldsymbol{k}$. The emergence of this mode leads to a wake with a short radial length-scale ahead of protoplanets, contributing to a positive torque, termed as ``Streaming Torque (ST)''. Furthermore, both Lindblad torque and corotation torque are affected by the NSH velocity. The total torque and planetary migration are contingent upon the coupling strength between dust and gas. In most scenarios, ST predominates, inducing outward migration for planets, thereby addressing the issue of rapid inward migration in their formation paradigm. △ Less

Submitted 3 August, 2024; originally announced August 2024.

Comments: Accepted to ApJ

First Indication of Solar $^8$B Neutrino Flux through Coherent Elastic Neutrino-Nucleus Scattering in PandaX-4T

Authors: PandaX Collaboration, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Zhaokan Cheng, Xiangyi Cui, Yingjie Fan, Deqing Fang, Zhixing Gao, Lisheng Geng, Karl Giboni, Xunan Guo, Xuyuan Guo, Zichao Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Di Huang, Houqi Huang, Junting Huang, Ruquan Hou, Yu Hou, Xiangdong Ji , et al. (77 additional authors not shown)

Abstract: The PandaX-4T liquid xenon detector at the China Jinping Underground Laboratory is used to measure the solar $^8$B neutrino flux by detecting neutrinos through coherent scattering with xenon nuclei. Data samples requiring the coincidence of scintillation and ionization signals (paired), as well as unpaired ionization-only signals (US2), are selected with energy threshold of approximately 1.1 keV (… ▽ More The PandaX-4T liquid xenon detector at the China Jinping Underground Laboratory is used to measure the solar $^8$B neutrino flux by detecting neutrinos through coherent scattering with xenon nuclei. Data samples requiring the coincidence of scintillation and ionization signals (paired), as well as unpaired ionization-only signals (US2), are selected with energy threshold of approximately 1.1 keV (0.33 keV) nuclear recoil energy. Combining the commissioning run and the first science run of PandaX-4T, a total exposure of 1.20 and 1.04 tonne$\cdot$year are collected for the paired and US2, respectively. After unblinding, 3 and 332 events are observed with an expectation of 2.8$\pm$0.5 and 251$\pm$32 background events, for the paired and US2 data, respectively. A combined analysis yields a best-fit $^8$B neutrino signal of 3.5 (75) events from the paired (US2) data sample, with $\sim$37\% uncertainty, and the background-only hypothesis is disfavored at 2.64$σ$ significance. This gives a solar $^8$B neutrino flux of ($8.4\pm3.1$)$\times$10$^6$ cm$^{-2}$s$^{-1}$, consistent with the standard solar model prediction. It is also the first indication of solar $^8$B neutrino ``fog'' in a dark matter direct detection experiment. △ Less

Submitted 13 September, 2024; v1 submitted 15 July, 2024; originally announced July 2024.

Comments: Accepted by Physical Review Letters

Light Dark Matter Constraints from SuperCDMS HVeV Detectors Operated Underground with an Anticoincidence Event Selection

Authors: SuperCDMS Collaboration, M. F. Albakry, I. Alkhatib, D. Alonso-González, D. W. P. Amaral, J. Anczarski, T. Aralis, T. Aramaki, I. J. Arnquist, I. Ataee Langroudy, E. Azadbakht, C. Bathurst, R. Bhattacharyya, A. J. Biffl, P. L. Brink, M. Buchanan, R. Bunker, B. Cabrera, R. Calkins, R. A. Cameron, C. Cartaro, D. G. Cerdeño, Y. -Y. Chang, M. Chaudhuri, J. -H. Chen , et al. (117 additional authors not shown)

Abstract: This article presents constraints on dark-matter-electron interactions obtained from the first underground data-taking campaign with multiple SuperCDMS HVeV detectors operated in the same housing. An exposure of 7.63 g-days is used to set upper limits on the dark-matter-electron scattering cross section for dark matter masses between 0.5 and 1000 MeV/$c^2$, as well as upper limits on dark photon k… ▽ More This article presents constraints on dark-matter-electron interactions obtained from the first underground data-taking campaign with multiple SuperCDMS HVeV detectors operated in the same housing. An exposure of 7.63 g-days is used to set upper limits on the dark-matter-electron scattering cross section for dark matter masses between 0.5 and 1000 MeV/$c^2$, as well as upper limits on dark photon kinetic mixing and axion-like particle axioelectric coupling for masses between 1.2 and 23.3 eV/$c^2$. Compared to an earlier HVeV search, sensitivity was improved as a result of an increased overburden of 225 meters of water equivalent, an anticoincidence event selection, and better pile-up rejection. In the case of dark-matter-electron scattering via a heavy mediator, an improvement by up to a factor of 25 in cross-section sensitivity was achieved. △ Less

Submitted 5 September, 2024; v1 submitted 10 July, 2024; originally announced July 2024.

Comments: 7 pages + title and references, 4 figures, and 1 table

Journal ref: Phys. Rev. D, 111 012006 (2025)

Rossby wave instability in weakly ionized protoplanetary disks. I. azimuthal or vertical B-fields

Authors: Can Cui, Ashutosh Tripathi, Cong Yu, Min-Kai Lin, Andrew Youdin

Abstract: Rossby wave instability (RWI) is considered the underlying mechanism to crescent-shaped azimuthal asymmetries, discovered in (sub-)millimeter dust continuum of many protoplanetary disks. Previous works on linear theory were conducted in the hydrodynamic limit. Nevertheless, protoplanetary disks are likely magnetized and weakly ionized. We examine the influence of magnetic fields and non-ideal magn… ▽ More Rossby wave instability (RWI) is considered the underlying mechanism to crescent-shaped azimuthal asymmetries, discovered in (sub-)millimeter dust continuum of many protoplanetary disks. Previous works on linear theory were conducted in the hydrodynamic limit. Nevertheless, protoplanetary disks are likely magnetized and weakly ionized. We examine the influence of magnetic fields and non-ideal magnetohydrodynamic (MHD) effects - namely, Ohmic resistivity, Hall drift, and ambipolar diffusion - on the RWI unstable modes. We perform radially global linear analyses, employing constant azimuthal ($B_φ$) or vertical ($B_z$) background magnetic fields. It is found that, in the ideal MHD regime, magnetism can either enhance or diminish RWI growth. Strong non-ideal MHD effects cause RWI growth rates to recover hydrodynamic results. The sign of Hall Elsässer number subtly complicates the results, and vertical wavenumbers generically diminish growth rates. △ Less

Submitted 12 January, 2025; v1 submitted 2 July, 2024; originally announced July 2024.

Comments: 13 pages, 4 figures, accepted for publication in MNRAS

A comprehensive comparison of spin-up and spin-down episodes of 4U 1538-522 observed with NuSTAR

Authors: Y. F. Hu, L. Ji, C. Yu

Abstract: 4U 1538-522 is a persistent high mass X-ray binary which exhibits secular spin evolution. In 2019, it underwent a torque reversal from spinning up to spinning down. We performed an extensive study using four NuSATR observations to compare temporal and spectral properties during different states. We observed no abrupt change in luminosity associated with the torque reversal. In addition, the pulse… ▽ More 4U 1538-522 is a persistent high mass X-ray binary which exhibits secular spin evolution. In 2019, it underwent a torque reversal from spinning up to spinning down. We performed an extensive study using four NuSATR observations to compare temporal and spectral properties during different states. We observed no abrupt change in luminosity associated with the torque reversal. In addition, the pulse profile, the spectral shape and the power spectrum remained unchanged before and after the torque reversal. The orbital and super-orbital modulation profiles also showed no significant changes. We discuss possible mechanisms for the torque reversal and conclude that it is unlikely to be caused by interactions between the accretion disk and the magnetosphere. Instead, the transition of accretion modes in spherical accretion may be a plausible explanation. △ Less

Submitted 17 June, 2024; originally announced June 2024.

Comments: 12 pages, 6 figures, 3 tables. Accepted by ApJ

Constraining Inflation with the BICEP/Keck CMB Polarization Experiments

Authors: The BICEP/Keck Collaboration, :, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, H. Boenish, V. Buza, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. Cukierman, E. V. Denison, M. Dierickx, L. Duband, M. Eiben, B. Elwood, S. Fatigoni, J. P. Filippini, M. Gao , et al. (63 additional authors not shown)

Abstract: The BICEP/$\textit{Keck}$ (BK) series of cosmic microwave background (CMB) polarization experiments has, over the past decade and a half, produced a series of field-leading constraints on cosmic inflation via measurements of the "B-mode" polarization of the CMB. Primordial B modes are directly tied to the amplitude of primordial gravitational waves (PGW), their strength parameterized by the tensor… ▽ More The BICEP/$\textit{Keck}$ (BK) series of cosmic microwave background (CMB) polarization experiments has, over the past decade and a half, produced a series of field-leading constraints on cosmic inflation via measurements of the "B-mode" polarization of the CMB. Primordial B modes are directly tied to the amplitude of primordial gravitational waves (PGW), their strength parameterized by the tensor-to-scalar ratio, $r$, and thus the energy scale of inflation. Having set the most sensitive constraints to-date on $r$, $σ(r)=0.009$ ($r_{0.05}<0.036, 95\%$ C.L.) using data through the 2018 observing season ("BK18"), the BICEP/$\textit{Keck}$ program has continued to improve its dataset in the years since. We give a brief overview of the BK program and the "BK18" result before discussing the program's ongoing efforts, including the deployment and performance of the $\textit{Keck Array}$'s successor instrument, BICEP Array, improvements to data processing and internal consistency testing, new techniques such as delensing, and how those will ultimately serve to allow BK reach $σ(r) \lesssim 0.003$ using data through the 2027 observing season. △ Less

Submitted 11 July, 2024; v1 submitted 29 May, 2024; originally announced May 2024.

Comments: 9 pages, 5 figures. Contribution to the 2024 Cosmology session of the 58th Rencontres de Moriond

Hall effect on the joint cascades of magnetic energy and helicity in helical magnetohydrodynamic turbulence

Authors: Running Hu, Jin-Han Xie, Xinliang Li, Changping Yu, Yuan Hu, Jianchun Wang, Shiyi Chen

Abstract: Helical magnetohydrodynamic turbulence with Hall effects is ubiquitous in heliophysics and plasma physics, such as star formation and solar activities, and its intrinsic mechanisms are still not clearly explained. Direct numerical simulations reveal that when the forcing scale is comparable to the ion inertial scale, Hall effects induce remarkable cross helicity. It then suppresses the inverse cas… ▽ More Helical magnetohydrodynamic turbulence with Hall effects is ubiquitous in heliophysics and plasma physics, such as star formation and solar activities, and its intrinsic mechanisms are still not clearly explained. Direct numerical simulations reveal that when the forcing scale is comparable to the ion inertial scale, Hall effects induce remarkable cross helicity. It then suppresses the inverse cascade efficiency, leading to the accumulation of large-scale magnetic energy and helicity. The process is accompanied by the breaking of current sheets via filaments along magnetic fields. Using the Ulysses data, the numerical findings are separately confirmed. These results suggest a novel mechanism wherein small-scale Hall effects could strongly affect large-scale magnetic fields through cross helicity. △ Less

Submitted 6 May, 2024; originally announced May 2024.

Comments: 5 figures, 6 pages

Accreting Black Holes in Dark Matter Halos

Authors: Sobhan Kazempour, Sichun Sun, Chengye Yu

Abstract: We examine the thin accretion disk behaviors surrounding black holes embedded in cold dark matter halos and scalar field dark matter halos. We first calculate the event horizons and derive the equations of motion and effective potential in black hole geometries with different dark matter halos. We then compute the specific energy, specific angular momentum, and angular velocity of particles moving… ▽ More We examine the thin accretion disk behaviors surrounding black holes embedded in cold dark matter halos and scalar field dark matter halos. We first calculate the event horizons and derive the equations of motion and effective potential in black hole geometries with different dark matter halos. We then compute the specific energy, specific angular momentum, and angular velocity of particles moving along circular orbits. We also derive the effective potentials to find the locations of the innermost stable circular orbit (ISCO) and compare them to the Schwarzschild and Kerr black holes without the dark matter haloes. We also use the observed ISCO of the supermassive black hole at the Galactic Center of the Milky Way, Sagittarius A*, to constrain the dark matter halos. △ Less

Submitted 30 August, 2024; v1 submitted 17 April, 2024; originally announced April 2024.

Comments: The published version of the paper in the Physical Review D journal

Journal ref: Phys. Rev. D 110, 043034 - Published 26 August 2024

The Impact-driven Atmospheric Loss of Super-Earths around Different Spectral Type Host Stars

Authors: Wei Zhong, Cong Yu, Shi Jia, Shang-Fei Liu

Abstract: The planet's mass loss is important for the planet's formation and evolution. The radius valley (RV) is believed to be triggered by evaporation-induced mass loss. As an alternative mechanism for the RV, the mass loss of post-impact planets is thoroughly investigated in this work. The impact energy is converted to the planet's internal energy, enhancing its core energy and accelerating mass loss an… ▽ More The planet's mass loss is important for the planet's formation and evolution. The radius valley (RV) is believed to be triggered by evaporation-induced mass loss. As an alternative mechanism for the RV, the mass loss of post-impact planets is thoroughly investigated in this work. The impact energy is converted to the planet's internal energy, enhancing its core energy and accelerating mass loss and orbital migration. As the host star changes from K-type to F-type, the planet's mass loss and orbital migration increase. When the initial gas-to-core mass ratio (GCR) is small, the migration efficiency for planets around K-type stars will increase, which helps to suppress mass loss and retain the planet's mass and radius within a specific range. On the contrary, planets around more massive F-type stars experience more substantial mass loss, potentially leading to complete mass loss, and migrate to orbits with longer periods. Our calculation shows that planets around different spectral types of host stars give rise to an RV ranging from 1.3-2.0 $R_{\oplus}$, consistent with the observed range of 1.3-2.6 $R_{\oplus}$. Despite the presence of uncertain parameters, the planetesimal impact can promote the RV establishment for planets around host stars of different spectral types. △ Less

Submitted 4 April, 2024; originally announced April 2024.

Comments: 19 pages, 12 figures; ApJ Accepted

PandaX-xT: a Multi-ten-tonne Liquid Xenon Observatory at the China Jinping Underground Laboratory

Authors: PandaX Collaboration, Abdusalam Abdukerim, Zihao Bo, Wei Chen, Xun Chen, Chen Cheng, Zhaokan Cheng, Xiangyi Cui, Yingjie Fan, Deqing Fang, Lisheng Geng, Karl Giboni, Linhui Gu, Xunan Guo, Xuyuan Guo, Zhichao Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Di Huang, Junting Huang, Zhou Huang, Ruquan Hou, Yu Hou , et al. (68 additional authors not shown)

Abstract: We propose a major upgrade to the existing PandaX-4T experiment in the China Jinping Underground Laboratory. The new experiment, PandaX-xT, will be a multi-ten-tonne liquid xenon, ultra-low background, and general-purpose observatory. The full-scaled PandaX-xT contains a 43-tonne liquid xenon active target. Such an experiment will significantly advance our fundamental understanding of particle phy… ▽ More We propose a major upgrade to the existing PandaX-4T experiment in the China Jinping Underground Laboratory. The new experiment, PandaX-xT, will be a multi-ten-tonne liquid xenon, ultra-low background, and general-purpose observatory. The full-scaled PandaX-xT contains a 43-tonne liquid xenon active target. Such an experiment will significantly advance our fundamental understanding of particle physics and astrophysics. The sensitivity of dark matter direct detection will be improved by nearly two orders of magnitude compared to the current best limits, approaching the so-called "neutrino floor" for a dark matter mass above 10 GeV/$c^2$, providing a decisive test to the Weakly Interacting Massive Particle paradigm. By searching for the neutrinoless double beta decay of $^{136}$Xe isotope in the detector, the effective Majorana neutrino mass can be measured to a [10 -- 41] meV/$c^2$ sensitivity, providing a key test to the Dirac/Majorana nature of neutrino s. Astrophysical neutrinos and other ultra-rare interactions can also be measured and searched for with an unprecedented background level, opening up new windows of discovery. Depending on the findings, PandaX-xT will seek the next stage upgrade utilizing isotopic separation on natural xenon. △ Less

Submitted 6 December, 2024; v1 submitted 5 February, 2024; originally announced February 2024.

Comments: version as published on SCPMA

Pulsar Kick by the Chiral Anisotropy Conversion

Authors: Kenji Fukushima, Chengpeng Yu

Abstract: We discuss a novel mechanism for the proto-neutron star acceleration assisted by the chiral separation effect which induces an axial vector current in a dense medium. We consider the process of neutrinos scattering off the background axial vector current of electrons. We show that anisotropy of either magnetic field or density in momentum space is essential for nonzero recoil and we call this mech… ▽ More We discuss a novel mechanism for the proto-neutron star acceleration assisted by the chiral separation effect which induces an axial vector current in a dense medium. We consider the process of neutrinos scattering off the background axial vector current of electrons. We show that anisotropy of either magnetic field or density in momentum space is essential for nonzero recoil and we call this mechanism the chiral anisotropy conversion. Assuming a strong magnetic field $B \simeq 10^{12}$ T and anisotropy by $\sim 10\%$, we find that the chiral anisotropy conversion can yield the velocity of order of typical pulsar kicks, i.e., $v_{\mathrm{kick}} \gtrsim 1000$ km/s. △ Less

Submitted 9 January, 2024; originally announced January 2024.

Comments: 6 pages, 4 figures

Crosstalk effects in microwave SQUID multiplexed TES bolometer readout

Authors: John C. Groh, Zeeshan Ahmed, Shawn W. Henderson, Johannes Hubmayr, John A. B. Mates, Maximiliano Silva-Feaver, Joel Ullom, Cyndia Yu

Abstract: Transition-edge sensor (TES) bolometers are broadly used for background-limited astrophysical measurements from the far-infrared to mm-waves. Many planned future instruments require increasingly large detector arrays, but their scalability is limited by their cryogenic readout electronics. Microwave SQUID multiplexing offers a highly capable scaling solution through the use of inherently broadband… ▽ More Transition-edge sensor (TES) bolometers are broadly used for background-limited astrophysical measurements from the far-infrared to mm-waves. Many planned future instruments require increasingly large detector arrays, but their scalability is limited by their cryogenic readout electronics. Microwave SQUID multiplexing offers a highly capable scaling solution through the use of inherently broadband circuitry, enabling readout of hundreds to thousands of channels per microwave line. As with any multiplexing technique, the channelization mechanism gives rise to electrical crosstalk which must be understood and controlled so as to not degrade the instrument sensitivity. Here, we explore implications relevant for TES bolometer array applications, focusing in particular on upcoming mm-wave observatories such as the Simons Observatory and AliCPT. We model the relative contributions of the various underlying crosstalk mechanisms, evaluate the difference between fixed-tone and tone-tracking readout systems, and discuss ways in which crosstalk nonlinearity will complicate on-sky measurements. △ Less

Submitted 8 April, 2024; v1 submitted 9 November, 2023; originally announced November 2023.

Comments: Accepted for publication in the Journal of Low Temperature Physics

Long-term Orbital Period Variation of Hot Jupiters from Transiting Time Analysis using TESS Survey Data

Authors: Wenqin Wang, Zixin Zhang, Zhangliang Chen, Yonghao Wang, Cong Yu, Bo Ma

Abstract: Many hot Jupiters may experience orbital decays, which are manifested as long-term transit timing variations. We have analyzed 7068 transits from the Transiting Exoplanet Survey Satellite (TESS) for a sample of 326 hot Jupiters. These new mid-transit time data allow us to update ephemerides for these systems. By combining the new TESS transit timing data with archival data, we search for possible… ▽ More Many hot Jupiters may experience orbital decays, which are manifested as long-term transit timing variations. We have analyzed 7068 transits from the Transiting Exoplanet Survey Satellite (TESS) for a sample of 326 hot Jupiters. These new mid-transit time data allow us to update ephemerides for these systems. By combining the new TESS transit timing data with archival data, we search for possible long-term orbital period variations in these hot Jupiters using a linear and a quadratic ephemeris model. We identified 26 candidates that exhibit possible long-term orbital period variations, including 18 candidates with decreasing orbital periods and 8 candidates with increasing orbital periods. Among them, 12 candidates have failed in our leave-one-out cross-validation (LOOCV) test and thus should be considered as marginal candidates. In addition to tidal interaction, alternative mechanisms such as apsidal precession, Rømer effect, and Applegate effect could also contribute to the observed period variations. The ephemerides derived in this work are useful for scheduling follow-up observations for these hot Jupiters in the future. The Python code used to generate the ephemerides is made available online. △ Less

Submitted 31 October, 2023; v1 submitted 26 October, 2023; originally announced October 2023.

Comments: Accepted for publication in ApJS

Results and Limits of Time Division Multiplexing for the BICEP Array High Frequency Receivers

Authors: S. Fatigoni, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, V. Buza, J. Cheshire, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. V. Denison, M. I. Dierickx, L. Duband, M. Eiben, J. P. Filippini, A. Fortes, M. Gao, C. Giannakopoulos, N. Goeckner-Wald, D. C. Goldfinger , et al. (62 additional authors not shown)

Abstract: Time-Division Multiplexing is the readout architecture of choice for many ground and space experiments, as it is a very mature technology with proven outstanding low-frequency noise stability, which represents a central challenge in multiplexing. Once fully populated, each of the two BICEP Array high frequency receivers, observing at 150GHz and 220/270GHz, will have 7776 TES detectors tiled on the… ▽ More Time-Division Multiplexing is the readout architecture of choice for many ground and space experiments, as it is a very mature technology with proven outstanding low-frequency noise stability, which represents a central challenge in multiplexing. Once fully populated, each of the two BICEP Array high frequency receivers, observing at 150GHz and 220/270GHz, will have 7776 TES detectors tiled on the focal plane. The constraints set by these two receivers required a redesign of the warm readout electronics. The new version of the standard Multi Channel Electronics, developed and built at the University of British Columbia, is presented here for the first time. BICEP Array operates Time Division Multiplexing readout technology to the limits of its capabilities in terms of multiplexing rate, noise and crosstalk, and applies them in rigorously demanding scientific application requiring extreme noise performance and systematic error control. Future experiments like CMB-S4 plan to use TES bolometers with Time Division/SQUID-based readout for an even larger number of detectors. △ Less

Submitted 24 October, 2023; v1 submitted 16 October, 2023; originally announced October 2023.

Comments: 10 pages, 7 figures, Submitted to Journal of Low Temperature Physics

Journal ref: Journal of Low Temperature Physics (2024)

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Authors: Angel Abusleme, Thomas Adam, Shakeel Ahmad, Rizwan Ahmed, Sebastiano Aiello, Muhammad Akram, Abid Aleem, Fengpeng An, Qi An, Giuseppe Andronico, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, Burin Asavapibhop, João Pedro Athayde Marcondes de André, Didier Auguste, Weidong Bai, Nikita Balashov, Wander Baldini, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Bellato, Marco Beretta, Antonio Bergnoli , et al. (606 additional authors not shown)

Abstract: The core-collapse supernova (CCSN) is considered one of the most energetic astrophysical events in the universe. The early and prompt detection of neutrinos before (pre-SN) and during the supernova (SN) burst presents a unique opportunity for multi-messenger observations of CCSN events. In this study, we describe the monitoring concept and present the sensitivity of the system to pre-SN and SN neu… ▽ More The core-collapse supernova (CCSN) is considered one of the most energetic astrophysical events in the universe. The early and prompt detection of neutrinos before (pre-SN) and during the supernova (SN) burst presents a unique opportunity for multi-messenger observations of CCSN events. In this study, we describe the monitoring concept and present the sensitivity of the system to pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton liquid scintillator detector currently under construction in South China. The real-time monitoring system is designed to ensure both prompt alert speed and comprehensive coverage of progenitor stars. It incorporates prompt monitors on the electronic board as well as online monitors at the data acquisition stage. Assuming a false alert rate of 1 per year, this monitoring system exhibits sensitivity to pre-SN neutrinos up to a distance of approximately 1.6 (0.9) kiloparsecs and SN neutrinos up to about 370 (360) kiloparsecs for a progenitor mass of 30 solar masses, considering both normal and inverted mass ordering scenarios. The pointing ability of the CCSN is evaluated by analyzing the accumulated event anisotropy of inverse beta decay interactions from pre-SN or SN neutrinos. This, along with the early alert, can play a crucial role in facilitating follow-up multi-messenger observations of the next galactic or nearby extragalactic CCSN. △ Less

Submitted 4 December, 2023; v1 submitted 13 September, 2023; originally announced September 2023.

Comments: 24 pages, 9 figures, accepted for the publication at JCAP