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X-ray Reflection and An Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143

Keek, L. and Iwakiri, W. and Serino, M. and Ballantyne, D. R. and in 't Zand, J. J. M. and Strohmayer, T. E. (2017) X-ray Reflection and An Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143. Astrophysical Journal, 836 (1). Art. No. 111. ISSN 1538-4357. doi:10.3847/1538-4357/836/1/111.

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Thermonuclear X-ray bursts from accreting neutron stars power brief but strong irradiation of their surroundings, providing a unique way to study accretion physics. We analyze MAXI/Gas Slit Camera and Swift/XRT spectra of a day-long flash observed from IGR J17062-6143 in 2015. It is a rare case of recurring bursts at a low accretion luminosity of 0.15% Eddington. Spectra from MAXI, Chandra, and NuSTAR observations taken between the 2015 burst and the previous one in 2012 are used to determine the accretion column. We find it to be consistent with the burst ignition column of 5 × 10^(10) g cm^(−2), which indicates that it is likely powered by burning in a deep helium layer. The burst flux is observed for over a day, and decays as a straight power law: F ∝ t^(-1.15). The burst and persistent spectra are well described by thermal emission from the neutron star, Comptonization of this emission in a hot optically thin medium surrounding the star, and reflection off the photoionized accretion disk. At the burst peak, the Comptonized component disappears, when the burst may dissipate the Comptonizing gas, and it returns in the burst tail. The reflection signal suggests that the inner disk is truncated at ~102 gravitational radii before the burst, but may move closer to the star during the burst. At the end of the burst, the flux drops below the burst cooling trend for 2 days, before returning to the pre-burst level.

Item Type:Article
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URLURL TypeDescription Paper
Ballantyne, D. R.0000-0001-8128-6976
Strohmayer, T. E.0000-0001-7681-5845
Additional Information:© 2017 The American Astronomical Society. Received 2016 October 24; revised 2017 January 13; accepted 2017 January 16; published 2017 February 13. L.K. is supported by NASA under award number NNG06EO90A. L.K. thanks the International Space Science Institute in Bern, Switzerland for hosting an International Team on X-ray bursts. This work benefited from events supported by the National Science Foundation under Grant No. PHY-1430152 (JINA Center for the Evolution of the Elements). This research has made use of MAXI data provided by RIKEN, JAXA, and the MAXI team. We thank the Swift observatory for performing the observations described in this paper.
Subject Keywords:accretion, accretion disks – stars: individual (IGR J17062-6143) – stars: neutron – X-rays: binaries – X-rays: bursts
Issue or Number:1
Record Number:CaltechAUTHORS:20161026-134501476
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Official Citation:L. Keek et al 2017 ApJ 836 111
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:71505
Deposited By: Joy Painter
Deposited On:27 Oct 2016 16:15
Last Modified:11 Nov 2021 04:46

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