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Title: X-Ray Reflection and an Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143

Abstract

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{sup 10} g cm{sup −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 {sup −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 suggestsmore » that the inner disk is truncated at ∼10{sup 2} 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.« less

Authors:
;  [1]; ;  [2];  [3];  [4]
  1. X-ray Astrophysics Laboratory, Astrophysics Science Division, NASA/GSFC, Greenbelt, MD 20771 (United States)
  2. MAXI team, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
  3. Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430 (United States)
  4. SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands)
Publication Date:
OSTI Identifier:
22663811
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 836; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; COSMIC X-RAY BURSTS; DECAY; EMISSION; HELIUM; IRRADIATION; LUMINOSITY; NEUTRON STARS; PHOTOIONIZATION; REFLECTION; SPECTRA; THERMONUCLEAR REACTIONS; X RADIATION

Citation Formats

Keek, L., Strohmayer, T. E., Iwakiri, W., Serino, M., Ballantyne, D. R., and Zand, J. J. M. in’t, E-mail: laurens.keek@nasa.gov. X-Ray Reflection and an Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143. United States: N. p., 2017. Web. doi:10.3847/1538-4357/836/1/111.
Keek, L., Strohmayer, T. E., Iwakiri, W., Serino, M., Ballantyne, D. R., & Zand, J. J. M. in’t, E-mail: laurens.keek@nasa.gov. X-Ray Reflection and an Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143. United States. doi:10.3847/1538-4357/836/1/111.
Keek, L., Strohmayer, T. E., Iwakiri, W., Serino, M., Ballantyne, D. R., and Zand, J. J. M. in’t, E-mail: laurens.keek@nasa.gov. Fri . "X-Ray Reflection and an Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143". United States. doi:10.3847/1538-4357/836/1/111.
@article{osti_22663811,
title = {X-Ray Reflection and an Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143},
author = {Keek, L. and Strohmayer, T. E. and Iwakiri, W. and Serino, M. and Ballantyne, D. R. and Zand, J. J. M. in’t, E-mail: laurens.keek@nasa.gov},
abstractNote = {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{sup 10} g cm{sup −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 {sup −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 ∼10{sup 2} 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.},
doi = {10.3847/1538-4357/836/1/111},
journal = {Astrophysical Journal},
number = 1,
volume = 836,
place = {United States},
year = {Fri Feb 10 00:00:00 EST 2017},
month = {Fri Feb 10 00:00:00 EST 2017}
}