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Modeling the light curves of ultraluminous X-ray sources as precession

Modeling the light curves of ultraluminous X-ray sources as precession
Modeling the light curves of ultraluminous X-ray sources as precession
We present a freely available xspec model for the modulations seen in the long-term light curves of multiple ultraluminous X-ray sources (ULXs). By incorporating the physics of multiple electron scatterings (ray traced with a Monte Carlo routine), we go beyond analytical predictions and show that the geometrical beaming of radiation in the conical outflow can be more than a factor of 100 for opening angles smaller than 10º. We apply our new model to the long-term, well-sampled Swift light curve of the recently confirmed ULX pulsar NGC 5907 X-1 with an established period of 78 d. Our results suggest that geometrical beaming together with a slight precession of the conical wind can describe the light curve with a consistent set of parameters for the wind. The small opening angle of roughly 10º−13º implies a highly supercritical flow and boosting factors of the order of B = 60–90 that would yield a fairly low surface magnetic field strength of 2 × 1010 G.
0035-8711
2236-2241
Dauser, T.
8f79578d-1fbc-44aa-8760-b54b5a80c6b9
Middleton, M.
f91b89d9-fd2e-42ec-aa99-1249f08a52ad
Wilms, J.
f2b198cf-f9f9-4b9e-b32d-c94011761754
Dauser, T.
8f79578d-1fbc-44aa-8760-b54b5a80c6b9
Middleton, M.
f91b89d9-fd2e-42ec-aa99-1249f08a52ad
Wilms, J.
f2b198cf-f9f9-4b9e-b32d-c94011761754

Dauser, T., Middleton, M. and Wilms, J. (2017) Modeling the light curves of ultraluminous X-ray sources as precession. Monthly Notices of the Royal Astronomical Society, 466 (2), 2236-2241. (doi:10.1093/mnras/stw3304).

Record type: Article

Abstract

We present a freely available xspec model for the modulations seen in the long-term light curves of multiple ultraluminous X-ray sources (ULXs). By incorporating the physics of multiple electron scatterings (ray traced with a Monte Carlo routine), we go beyond analytical predictions and show that the geometrical beaming of radiation in the conical outflow can be more than a factor of 100 for opening angles smaller than 10º. We apply our new model to the long-term, well-sampled Swift light curve of the recently confirmed ULX pulsar NGC 5907 X-1 with an established period of 78 d. Our results suggest that geometrical beaming together with a slight precession of the conical wind can describe the light curve with a consistent set of parameters for the wind. The small opening angle of roughly 10º−13º implies a highly supercritical flow and boosting factors of the order of B = 60–90 that would yield a fairly low surface magnetic field strength of 2 × 1010 G.

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Modeling the light curves of ultraluminous X-ray sources as - Accepted Manuscript
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Accepted/In Press date: 14 December 2016
e-pub ahead of print date: 17 December 2016
Published date: April 2017
Organisations: Astronomy Group

Identifiers

Local EPrints ID: 412029
URI: http://eprints.soton.ac.uk/id/eprint/412029
ISSN: 0035-8711
PURE UUID: 9cf623e4-c245-4771-832c-ed9f854c5384

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Date deposited: 05 Jul 2017 16:31
Last modified: 06 Oct 2020 16:40

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