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Study of the X-ray properties of the neutron star binary 4U 1728–34 from the soft-to-hard state

Study of the X-ray properties of the neutron star binary 4U 1728–34 from the soft-to-hard state
Study of the X-ray properties of the neutron star binary 4U 1728–34 from the soft-to-hard state
We studied five XMM–Newton observations of the neutron star binary 4U 1728–34 covering the hard, intermediate and soft spectral states. By jointly fitting the spectra with several reflection models, we obtained an inclination angle of 25º–53º and an iron abundance up to 10 times the solar. From the fits with reflection models, we found that the fluxes of the reflection and the Comptonized components vary inconsistently; since the latter is assumed to be the illuminating source, this result possibly indicates the contribution of the neutron star surface/boundary layer to the disc reflection. As the source evolved from the relatively soft to the intermediate state, the disc inner radius decreased, opposite to the prediction of the standard accretion disc model. We also explore the possible reasons why the supersolar iron abundance is required by the data and found that this high value is probably caused by the absence of the hard photons in the XMM–Newton data.
0035-8711
3004-3016
Wang, Yanan
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Méndez, Mariano
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Altamirano, Diego
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Zhang, Guobao
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Belloni, T. M.
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Ribeiro, Evandro M
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Linares, M.
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Sanna, Andrea
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Motta, S. E.
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Tomsick, John A.
96b2e8cc-70c1-424a-8380-2551a5077ff5
Wang, Yanan
b412bbe8-8159-4b94-b485-ef154731aa85
Méndez, Mariano
5cc6f759-dae2-488a-9cc2-cff89f4eca72
Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b
Zhang, Guobao
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Belloni, T. M.
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Ribeiro, Evandro M
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Linares, M.
cea3a79a-1831-4a7f-be41-3bf3b7b25383
Sanna, Andrea
2c05dccc-d674-4ca7-b324-730eb73d6a36
Motta, S. E.
b6813310-4162-4bb5-985e-c6daaa33f2e1
Tomsick, John A.
96b2e8cc-70c1-424a-8380-2551a5077ff5

Wang, Yanan, Méndez, Mariano, Altamirano, Diego, Zhang, Guobao, Belloni, T. M., Ribeiro, Evandro M, Linares, M., Sanna, Andrea, Motta, S. E. and Tomsick, John A. (2019) Study of the X-ray properties of the neutron star binary 4U 1728–34 from the soft-to-hard state. Monthly Notices of the Royal Astronomical Society, 484 (3), 3004-3016. (doi:10.1093/mnras/stz169).

Record type: Article

Abstract

We studied five XMM–Newton observations of the neutron star binary 4U 1728–34 covering the hard, intermediate and soft spectral states. By jointly fitting the spectra with several reflection models, we obtained an inclination angle of 25º–53º and an iron abundance up to 10 times the solar. From the fits with reflection models, we found that the fluxes of the reflection and the Comptonized components vary inconsistently; since the latter is assumed to be the illuminating source, this result possibly indicates the contribution of the neutron star surface/boundary layer to the disc reflection. As the source evolved from the relatively soft to the intermediate state, the disc inner radius decreased, opposite to the prediction of the standard accretion disc model. We also explore the possible reasons why the supersolar iron abundance is required by the data and found that this high value is probably caused by the absence of the hard photons in the XMM–Newton data.

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Accepted/In Press date: 14 January 2019
e-pub ahead of print date: 16 January 2019
Published date: 11 April 2019

Identifiers

Local EPrints ID: 430175
URI: http://eprints.soton.ac.uk/id/eprint/430175
ISSN: 0035-8711
PURE UUID: f567f416-f71a-4bca-9ece-f816cd5b9fbc
ORCID for Diego Altamirano: ORCID iD orcid.org/0000-0002-3422-0074

Catalogue record

Date deposited: 16 Apr 2019 16:30
Last modified: 26 Nov 2021 03:02

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Contributors

Author: Yanan Wang
Author: Mariano Méndez
Author: Guobao Zhang
Author: T. M. Belloni
Author: Evandro M Ribeiro
Author: M. Linares
Author: Andrea Sanna
Author: S. E. Motta
Author: John A. Tomsick

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