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The reflection component in the average and heartbeat spectra of the black hole candidate IGR J17091-3642 during the 2016 outburst

The reflection component in the average and heartbeat spectra of the black hole candidate IGR J17091-3642 during the 2016 outburst
The reflection component in the average and heartbeat spectra of the black hole candidate IGR J17091-3642 during the 2016 outburst

We present simultaneous NuSTAR and Swift observations of the black hole transient IGR J17091-3642 during its 2016 outburst. By jointly fitting six NuSTAR and four Swift spectra, we found that during this outburst the source evolves from the hard to the hard/soft intermediate and back to the hard state, similar to the 2011 outburst. Unlike in the previous outburst, in this case we observed both a broad emission and a moderately broad absorption line in our observations. Our fits favour an accretion disc with an inclination angle of ~45° with respect to the line of sight and a high iron abundance of 3.5 ± 0.3 in units of the solar abundance. We also observed heartbeat variability in one NuSTAR observation. We fitted the phase-resolved spectra of this observation and found that the reflected emission varies independently from the direct emission, whereas in the fits to the average spectra these two quantities are strongly correlated. Assuming that in IGR J17091-3642 the inner radius of the disc both in the average and the phase-resolved spectra is located at the radius of the innermost stable circular orbit, with 90 per cent confidence the spin parameter of the black hole in this system is -0.13 ≤a* ≤ 0.27.

Accretion, Accretion discs, Black hole physics, X-rays: binaries
0035-8711
4837-4850
Wang, Yanan
37b2021a-5d54-4360-ace2-4fc34e69ee90
Méndez, Mariano
5cc6f759-dae2-488a-9cc2-cff89f4eca72
Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b
Court, James
46f2d76f-29e8-49f6-96cb-bde1ad082147
Beri, Aru
69ed346a-f02a-4243-83f9-ad5ab4c4008c
Cheng, Zheng
150adaed-6ec2-4476-8896-8b38ea2a3cda
Wang, Yanan
37b2021a-5d54-4360-ace2-4fc34e69ee90
Méndez, Mariano
5cc6f759-dae2-488a-9cc2-cff89f4eca72
Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b
Court, James
46f2d76f-29e8-49f6-96cb-bde1ad082147
Beri, Aru
69ed346a-f02a-4243-83f9-ad5ab4c4008c
Cheng, Zheng
150adaed-6ec2-4476-8896-8b38ea2a3cda

Wang, Yanan, Méndez, Mariano, Altamirano, Diego, Court, James, Beri, Aru and Cheng, Zheng (2018) The reflection component in the average and heartbeat spectra of the black hole candidate IGR J17091-3642 during the 2016 outburst. Monthly Notices of the Royal Astronomical Society, 478 (4), 4837-4850. (doi:10.1093/mnras/sty1372).

Record type: Article

Abstract

We present simultaneous NuSTAR and Swift observations of the black hole transient IGR J17091-3642 during its 2016 outburst. By jointly fitting six NuSTAR and four Swift spectra, we found that during this outburst the source evolves from the hard to the hard/soft intermediate and back to the hard state, similar to the 2011 outburst. Unlike in the previous outburst, in this case we observed both a broad emission and a moderately broad absorption line in our observations. Our fits favour an accretion disc with an inclination angle of ~45° with respect to the line of sight and a high iron abundance of 3.5 ± 0.3 in units of the solar abundance. We also observed heartbeat variability in one NuSTAR observation. We fitted the phase-resolved spectra of this observation and found that the reflected emission varies independently from the direct emission, whereas in the fits to the average spectra these two quantities are strongly correlated. Assuming that in IGR J17091-3642 the inner radius of the disc both in the average and the phase-resolved spectra is located at the radius of the innermost stable circular orbit, with 90 per cent confidence the spin parameter of the black hole in this system is -0.13 ≤a* ≤ 0.27.

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More information

Accepted/In Press date: 22 May 2018
e-pub ahead of print date: 25 May 2018
Published date: 21 August 2018
Keywords: Accretion, Accretion discs, Black hole physics, X-rays: binaries

Identifiers

Local EPrints ID: 424781
URI: http://eprints.soton.ac.uk/id/eprint/424781
ISSN: 0035-8711
PURE UUID: 00394009-d06a-45e8-b020-b6f6e09bd436
ORCID for Diego Altamirano: ORCID iD orcid.org/0000-0002-3422-0074

Catalogue record

Date deposited: 05 Oct 2018 11:45
Last modified: 26 Nov 2021 03:02

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Contributors

Author: Yanan Wang
Author: Mariano Méndez
Author: James Court
Author: Aru Beri
Author: Zheng Cheng

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