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A broad-band self-consistent modelling of the X-ray spectrum of 4U 1626−67

D'Aì, A. and Cusumano, G. and Del Santo, M. and La Parola, V. and Segreto, A. (2017) A broad-band self-consistent modelling of the X-ray spectrum of 4U 1626−67. Monthly Notices of the Royal Astronomical Society, 470 (2). pp. 2457-2468. ISSN 0035-8711. https://resolver.caltech.edu/CaltechAUTHORS:20170511-100805973

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Abstract

The accretion-powered X-ray pulsar 4U 1626−67 is one of the few highly magnetized pulsars that accretes through Roche lobe overflow from a low-mass companion. The characteristics of its broad-band spectrum are similar to those of X-ray pulsars hosted in a high-mass X-ray binary system, with a broad resonant cyclotron scattering feature (CRSF) at ∼37 keV. In this work, we examine the pulse-resolved and the pulse-averaged broad-band spectrum using data from NuSTAR and Swift. We use the Becker & Wolff model of bulk+thermal Comptonization to infer key physical parameters of the accretion column flow and a broad-band model for the disc-reflected spectrum. In the softer X-ray band, we need to add a soft blackbody component with kT_(bb) ∼ 0.5 keV, whose characteristics indicate a possible origin from the neutron star surface. Residuals suggest that the shape of the cyclotron line could be more satisfactorily fitted using a narrow core and broader wings and, at higher energies, a second harmonic could be present at ∼61 keV.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/mnras/stx1146DOIArticle
https://academic.oup.com/mnras/article-abstract/470/2/2457/3815540PublisherArticle
http://arxiv.org/abs/1705.03404arXivDiscussion Paper
ORCID:
AuthorORCID
D'Aì, A.0000-0002-5042-1036
La Parola, V.0000-0002-8087-6488
Additional Information:© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 May 8. Received 2017 May 7; in original form 2016 December 28. Published: 11 May 2017. AD acknowledges contract ASI-INAF I/004/11/0.We acknowledge the NASA High Energy Astrophysics Science Archive Research Center (HEASARC) for developing and maintaining the HEASOFT software that has been used in this study.
Group:NuSTAR
Subject Keywords:line: identification – line: formation – stars: individual (4U 1626–67)—X-rays: binaries— X-rays: general
Issue or Number:2
Record Number:CaltechAUTHORS:20170511-100805973
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170511-100805973
Official Citation:A. D'Aì, G. Cusumano, M. Del Santo, V. La Parola, A. Segreto; A broad-band self-consistent modelling of the X-ray spectrum of 4U 1626−67, Monthly Notices of the Royal Astronomical Society, Volume 470, Issue 2, 11 September 2017, Pages 2457–2468, https://doi.org/10.1093/mnras/stx1146
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77370
Collection:CaltechAUTHORS
Deposited By: Joy Painter
Deposited On:11 May 2017 19:33
Last Modified:04 Mar 2020 19:11

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