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Spectral analysis of new black hole candidate AT2019wey observed by NuSTAR

Feng, Ye and Zhao, XueShan and Gou, LiJun and Liu, YuFeng and Steiner, James F. and García, Javier A. and Wang, Yuan and Jia, Nan and Liao, ZhenXuan and Li, HuiXian (2022) Spectral analysis of new black hole candidate AT2019wey observed by NuSTAR. Science China Physics, Mechanics and Astronomy, 65 (1). Art. No. 219512. ISSN 1674-7348. doi:10.1007/s11433-021-1790-7.

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AT2019wey is a new galactic X-ray binary that was first discovered as an optical transient by the Australia Telescope Large Area Survey (ATLAS) on December 7, 2019. AT2019wey consists of a black hole candidate as well as a low-mass companion star (M_(star) ≲ 1.0 M_⊙) and is likely to have a short orbital period (P_(orb) ≲16 h). Although AT2019wey began activation in the X-ray band during almost the entire outburst on March 8, 2020, it did not enter the soft state during the entire outburst. In this study, we present a detailed spectral analysis of AT2019wey in the low/hard state during its X-ray outburst on the basis of Nuclear Spectroscopic Telescope Array \emph observations. We obtain tight constraints on several of its important physical parameters by applying the State-of-art \texttt{relxill} relativistic reflection model family. In particular, we determine that the measured inner radius of the accretion disk is most likely to have extended to the innermost stable circular orbit (ISCO) radius, i.e., R_(in) = 1.38^(+0.23)_(−0.16) R_(ISCO). Hence, assuming R_(in) = R_(ISCO), we find the spin of AT2019wey to be a∗∼ 0.97, which is close to the extreme and an inner disk inclination angle of ~i∼ 22∘. Additionally, according to our adopted models, AT2019wey tends to have a relatively high iron abundance of A_(Fe)∼ 5 A_(Fe,⊙) and a high disk ionization state of log ξ∼ 3.4.

Item Type:Article
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URLURL TypeDescription Paper ReadCube access
Liu, YuFeng0000-0002-1686-0545
Steiner, James F.0000-0002-5872-6061
García, Javier A.0000-0003-3828-2448
Additional Information:c Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature 2021. Received August 15, 2021; accepted September 16, 2021; published online November 24, 2021. Ye Feng thanks the useful discussions with Prof. Mihoko Yukita on extracting NuSTAR spectrum. Ye Feng also thanks the useful discussions with Yunfeng Chen. The software used is provided by the High Energy Astrophysics Science Archive Research Centre (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC and the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Space Science Data Center (SSDC, Italy) and the California Institute of Technology (Caltech, USA). LiJun Gou is supported by the National Program on Key Research and Development Project (Grant No. 2016YFA0400804), the National Natural Science Foundation of China (Grant No. U1838114), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB23040100).
Group:Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
National Key Research and Development Program of China2016YFA0400804
National Natural Science Foundation of ChinaU1838114
Chinese Academy of SciencesXDB23040100
Subject Keywords:NuSTAR, black hole physics, X-rays, binaries-stars, individual, AT2019we
Issue or Number:1
Classification Code:PACS number(s): 01.55.+b, 04.70.-s, 07.85.Fv
Record Number:CaltechAUTHORS:20211208-951173000
Persistent URL:
Official Citation:Feng, Y., Zhao, X., Gou, L. et al. Spectral analysis of new black hole candidate AT2019wey observed by NuSTAR. Sci. China Phys. Mech. Astron. 65, 219512 (2022).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112308
Deposited By: George Porter
Deposited On:10 Dec 2021 19:39
Last Modified:10 Dec 2021 22:57

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