A Comprehensive X-Ray Report on AT2019wey

Yao Y, Kulkarni SR, Gendreau KC, Jaisawal GK, Enoto T, Grefenstette BW, Marshall HL, Garcia JA, Ludlam RM, Pike SN, Ng M, Zhang L, Altamirano D, Jaodand A, Cenko SB, Remillard RA, Steiner JF, Negoro H, Brightman M, Lien A, Wolff MT, Ray PS, Mukai K, Wadiasingh Z, Arzoumanian Z, Kawai N, Mihara T, Strohmayer TE (2021)

Publication Type: Journal article

Publication year: 2021


Book Volume: 920

Article Number: 121

Journal Issue: 2

DOI: 10.3847/1538-4357/ac15f8


Here, we present MAXI, Swift, NICER, NuSTAR, and Chandra observations of the X-ray transient AT2019wey (SRGA J043520.9+552226, SRGE J043523.3+552234). From spectral and timing analyses we classify it as a Galactic low-mass X-ray binary (LMXB) with a black hole (BH) or neutron star (NS) accretor. AT2019wey stayed in the low/hard state (LHS) from 2019 December to 2020 August 21, and the hard-intermediate state (HIMS) from 2020 August 21 to 2020 November. For the first six months of the LHS, AT2019wey had a flux of ∼1 mCrab, and displayed a power-law X-ray spectrum with photon index Γ = 1.8. From 2020 June to August, it brightened to ∼20 mCrab. Spectral features characteristic of relativistic reflection became prominent. On 2020 August 21, the source left the "hard line"on the rms-intensity diagram, and transitioned from LHS to HIMS. The thermal disk component became comparable to the power-law component. A low-frequency quasi-periodic oscillation (QPO) was observed. The QPO central frequency increased as the spectrum softened. No evidence of pulsation was detected. We are not able to decisively determine the nature of the accretor (BH or NS). However, the BH option is favored by the position of this source on the Γ-L X, L radio-L X, and L opt-L X diagrams. We find the BH candidate XTE J1752-223 to be an analog of AT2019wey. Both systems display outbursts with long plateau phases in the hard states. We conclude by noting the potential of SRG in finding new members of this emerging class of low luminosity and long-duration LMXB outbursts.

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How to cite


Yao, Y., Kulkarni, S.R., Gendreau, K.C., Jaisawal, G.K., Enoto, T., Grefenstette, B.W.,... Strohmayer, T.E. (2021). A Comprehensive X-Ray Report on AT2019wey. Astrophysical Journal, 920(2). https://doi.org/10.3847/1538-4357/ac15f8


Yao, Yuhan, et al. "A Comprehensive X-Ray Report on AT2019wey." Astrophysical Journal 920.2 (2021).

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