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Photospheric Radius Expansion and a Double-peaked Type-I X-Ray Burst from GRS 1741.9–2853

Pike, Sean N. and Harrison, Fiona A. and Tomsick, John A. and Bachetti, Matteo and Buisson, Douglas J. K. and García, Javier A. and Jiang, Jiachen and Ludlam, R. M. and Madsen, Kristin K. (2021) Photospheric Radius Expansion and a Double-peaked Type-I X-Ray Burst from GRS 1741.9–2853. Astrophysical Journal, 918 (1). Art. No. 9. ISSN 0004-637X. doi:10.3847/1538-4357/ac0ef9.

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We present an analysis of two type-I X-ray bursts observed by NuSTAR originating from the very faint transient neutron star (NS) low-mass X-ray binary GRS 1741.9–2853 during a period of outburst in 2020 May. We show that the persistent emission can be modeled as an absorbed, Comptonized blackbody in addition to Fe Kα emission, which can be attributed to relativistic disk reflection. We measure a persistent bolometric, unabsorbed luminosity of L_(bol) = 7.03_(-0.05)^(+0.04) x 10³⁶ erg s⁻¹, assuming a distance of 7 kpc, corresponding to an Eddington ratio of 4.5%. This persistent luminosity combined with light-curve analysis leads us to infer that the bursts were the result of pure He burning rather than mixed H/He burning. Time-resolved spectroscopy reveals that the bolometric flux of the first burst exhibits a double-peaked structure, placing the source within a small population of accreting NSs that exhibit multiple-peaked type-I X-ray bursts. We find that the second, brighter burst shows evidence for photospheric radius expansion (PRE) and that at its peak, this PRE event had an unabsorbed bolometric flux of F_(peak) = 2.94_(-0.26)^(+0.28) x 10⁻⁸ erg cm⁻² s⁻¹. This yields a new distance estimate of d = 9.0 ± 0.5 kpc, assuming that this corresponds to the Eddington limit for pure He burning on the surface of a canonical NS. Additionally, we performed a detailed timing analysis that failed to find evidence for quasi-periodic oscillations or burst oscillations, and we place an upper limit of 16% on the rms variability around 589 Hz, the frequency at which oscillations have previously been reported.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Pike, Sean N.0000-0002-8403-0041
Harrison, Fiona A.0000-0003-2992-8024
Tomsick, John A.0000-0001-5506-9855
Bachetti, Matteo0000-0002-4576-9337
García, Javier A.0000-0003-3828-2448
Jiang, Jiachen0000-0002-9639-4352
Ludlam, R. M.0000-0002-8961-939X
Madsen, Kristin K.0000-0003-1252-4891
Additional Information:© 2021. The American Astronomical Society. Received 2021 March 15; revised 2021 June 16; accepted 2021 June 24; published 2021 August 30. J.J. acknowledges support by the Tsinghua Astrophysics Outstanding (TAO) Fellowship and the Tsinghua Shuimu Scholar Programme. R.M.L. acknowledges the support of NASA through Hubble Fellowship Program grant HST-HF2-51440.001. D.J.K.B. acknowledges support from the Royal Society. J.A.G. acknowledges support from NASA ATP grant 80NSSC20K0540 and from the Alexander von Humboldt Foundation. This work was partially supported under NASA contract No. NNG08FD60C and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS), jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). We would also like to acknowledge the insightful feedback provided by the reviewer, which significantly improved the quality of this work. Software: Astropy, DS9, Scipy, Stingray, XSpec.
Group:Astronomy Department, Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Tsinghua UniversityUNSPECIFIED
NASA Hubble FellowshipHST-HF2-51440.001
Alexander von Humboldt FoundationUNSPECIFIED
Subject Keywords:Neutron stars; Low-mass x-ray binary stars; X-ray bursts; X-ray sources
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Neutron stars (1108); Low-mass x-ray binary stars (939); X-ray bursts (1814); X-ray sources (1822)
Record Number:CaltechAUTHORS:20210914-225403760
Persistent URL:
Official Citation:Sean N. Pike et al 2021 ApJ 918 9
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110897
Deposited By: George Porter
Deposited On:16 Sep 2021 21:47
Last Modified:16 Sep 2021 21:47

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