High-energy characteristics of the accretion-powered millisecond pulsar IGR J17591-2342 during its 2018 outburst: XMM-Newton, NICER, NuSTAR, and INTEGRAL view of the 0.3-300 keV X-ray band

被引：0

作者：

Kuiper, L. ^{[1
]}

Tsygankov, S.S. ^{[2
,3
]}

Falanga, M. ^{[4
,5
]}

Mereminskiy, I.A. ^{[3
]}

Galloway, D.K. ^{[6
,7
]}

Poutanen, J. ^{[2
,3
,8
]}

Li, Z. ^{[9
]}

机构：

[1] SRON-Netherlands Institute for Space Research, Sorbonnelaan 2, Utrecht,CA,3584, Netherlands

[2] Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Turku,20014, Finland

[3] Space Research Institute of the Russian Academy of Sciences, Profsoyuznaya Str. 84/32, Moscow,117997, Russia

[4] International Space Science Institute (ISSI), Hallerstrasse 6, Bern,3012, Switzerland

[5] International Space Science Institute Beijing, No. 1 Nanertiao, Zhongguancun, Haidian District, Beijing,100190, China

[6] School of Physics and Astronomy, Monash University Australia, Clayton,VIC,3800, Australia

[7] Monash Centre for Astrophysics, Monash University Australia, Clayton,VIC,3800, Australia

[8] Nordita, Kth Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, Stockholm,10691, Sweden

[9] Department of Physics, Xiangtan University, Xiangtan,411105, China

来源：

Astronomy and Astrophysics | 2020年 / 641卷

关键词：

IGR J17591-2342 is an accreting millisecond X-ray pulsar; discovered with INTEGRAL; which went into outburst around July 21; 2018. To better understand the physics acting in these systems during the outburst episode; we performed detailed temporal-; timing-; and spectral analyses across the 0.3-300 keV band using data from NICER; XMM-Newton; NuSTAR; and INTEGRAL. The hard X-ray 20-60 keV outburst profile covering ∼85 days is composed of four flares. Over the course of the maximum of the last flare; we discovered a type-I thermonuclear burst in INTEGRAL JEM-X data; posing constraints on the source distance. We derived a distance of 7.6 ± 0.7 kpc; adopting Eddington-limited photospheric radius expansion and assuming anisotropic emission. In the timing analysis; using all NICER 1-10 keV monitoring data; we observed a rather complex set of behaviours starting with a spin-up period (MJD 58345-58364); followed by a frequency drop (MJD 58364-58370); an episode of constant frequency (MJD 58370-58383); concluded by irregular behaviour till the end of the outburst. The 1-50 keV phase distributions of the pulsed emission; detected up to ∼120 keV using INTEGRAL ISGRI data; was decomposed in three Fourier harmonics showing that the pulsed fraction of the fundamental increases from ∼10% to ∼17% going from ∼1.5 to ∼4 keV; while the harder photons arrive earlier than the soft photons for energies 10 keV. The total emission spectrum of IGR J17591-2342 across the 0.3-150 keV band could adequately be fitted in terms of an absorbed COMPPS model yielding as best fit parameters a column density of NH = (2.09 ± 0.05) × 1022 cm-2; a blackbody seed photon temperature kTbb; seed of 0.64 ± 0.02 keV; electron temperature kTe = 38.8 ± 1.2 keV and Thomson optical depth τT = 1.59 ± 0.04. The fit normalisation results in an emission area radius of 11.3 ± 0.5 km adopting a distance of 7.6 kpc. Finally; the results are discussed within the framework of accretion physics- and X-ray thermonuclear burst theory. © ESO 2020;

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