Search Publications
Extracting the X-Ray Reverberation Response Functions from the Active Galactic Nucleus Light Curves Using an Autoencoder
Chainakun, Poemwai; Jiang, Jiachen; Young, Andrew J. +5 more
We study the X-ray reverberation in active galactic nuclei (AGN) using the variational autoencoder (VAE), which is a machine learning algorithm widely used for signal processing and feature reconstruction. While the X-ray reverberation signatures that contain the information of the accretion disk and the X-ray-emitting corona are commonly analyzed…
Milky Way Dark Matter Distribution or MOND Test from Vertical Stellar Kinematics with Gaia DR3
López-Corredoira, Martín
Vertical stellar kinematics+density can be used to trace the dark matter distribution (or the equivalent phantom mass in a Modified Newtonian Dynamics (MOND) scenario) through the Jeans equations. In this paper, we want to improve this type of analysis by making use of the recent data of the 6D information from the Gaia DR3 survey in the anticente…
Stellar Streams Reveal the Mass Loss of Globular Clusters
Li, Hui; Chen, Yingtian; Gnedin, Oleg Y.
Globular cluster (GC) streams, debris of stars tidally stripped from their progenitor GCs, have densities that correlate positively with the GC mass-loss rate. In this work, we employ a novel particle spray algorithm that can accurately reproduce the morphology of streams of various orbital types, enabling us to uncover the relationship between th…
ALMA Observations of Solar Spicules in a Polar Coronal Hole
Nindos, A.; White, S. M.; Shimojo, M. +2 more
We report observations of solar spicules at millimeter wavelengths (mm-λ) using the Atacama Large Millimeter/submillimeter Array (ALMA). These are supplemented by observations in optical, ultraviolet (UV), and extreme ultraviolet (EUV) wavelengths. The observations were made on 2018 December 25 of the northern polar coronal hole. ALMA obtained tim…
A UV to X-Ray View of Soft Excess in Type 1 Active Galactic Nuclei. I. Sample Selection and Spectral Profile
Kang, Jia-Lai; Cai, Zhen-Yi; Wang, Jun-Xian +5 more
A core sample of 59 unobscured type 1 active galactic nuclei (AGNs) with simultaneous XMM-Newton X-ray and UV observations is compiled from the archives to probe the nature of soft X-ray excess (SE). In the first paper of this series, our focus centers on scrutinizing the spectral profile of the soft excess. Of the sources, ≈71% (42/59) exhibit po…
Can Alfvénic Fluctuations Affect the Correlation and Complexity of Magnetic Field of Magnetic Ejecta? A Case Study Based on Multi-spacecraft Measurements at 1 au
Lugaz, Noé; Zhuang, Bin; Scolini, Camilla +4 more
We investigate whether Alfvénic fluctuations (AFs) can affect the structure of magnetic ejecta (ME) within interplanetary coronal mass ejections (ICMEs). We study an ICME observed on 2001 December 29 at 1 au by the Advanced Composition Explorer (ACE) and Wind, at a total angular separation of ~0
The Magnetically Induced Radial Velocity Variation of Gliese 341 and an Upper Limit to the Mass of Its Transiting Earth-sized Planet
Lustig-Yaeger, Jacob; Fu, Guangwei; Peacock, Sarah +5 more
The Transiting Exoplanet Survey Satellite (TESS) mission identified a potential 0.88R⊕ planet with a period of 7.577 days, orbiting the nearby M1V star GJ 341 (TOI 741.01). This system has already been observed by the James Webb Space Telescope (JWST) to search for presence of an atmosphere on this planet. Here, we present an in-depth a…
Prediction of Star Formation Rates Using an Artificial Neural Network
Woo, Jong-Hak; Ayubinia, Ashraf; Kim, Changseok +2 more
In this study we develop an artificial neural network to estimate the infrared (IR) luminosity and star formation rates (SFR) of galaxies. Our network is trained using "true" IR luminosity values derived from modeling the IR spectral energy distributions of FIR-detected galaxies. We explore five different sets of input features, each incorporating…
Simultaneous NICER and NuSTAR Observations of the Neutron Star Low-mass X-Ray Binary Serpens X-1
Fabian, A. C.; Miller, J. M.; Tomsick, J. A. +5 more
We present the first contemporaneous NICER and NuSTAR analysis of the low-mass X-ray binary Serpens X-1 obtained in 2023 June, performing broadband X-ray spectral analysis modeling of the reprocessed emission with RELXILLNS from 0.4 to 30 keV. We test various continuum and background estimation models to ensure that our results do not hinge on the…
Sloan Digital Sky Survey IV MaStar: Quantification and Abatement of Interstellar Absorption in the Largest Empirical Stellar Spectral Library
Law, David R.; Howk, J. Christopher; Thomas, Daniel +6 more
We assess the impact of Ca II λ λ3934, 3969 and Na I λ λ5891, 5897 absorption arising in the interstellar medium (ISM) on the Sloan Digital Sky Survey-IV MaNGA Stellar Library (MaStar) and produce corrected spectroscopy for 80% of the 24,162-star catalog. We model the absorption strength of these transitions as a function of the stellar distance, …