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Orbital and superorbital periods in ULX pulsars, disc-fed HMXBs, Be/X-ray binaries, and double-periodic variables

Orbital and superorbital periods in ULX pulsars, disc-fed HMXBs, Be/X-ray binaries, and double-periodic variables
Orbital and superorbital periods in ULX pulsars, disc-fed HMXBs, Be/X-ray binaries, and double-periodic variables
We present evidence for a simple linear relationship between the orbital period and superorbital period in ultra-luminous X-ray (ULX) pulsars, akin to what is seen in the population of disc-fed neutron star supergiant X-ray binary and Be/X-ray binary systems. We argue that the most likely cause of this relationship is the modulation of precessing hotspots or density waves in an accretion or circumstellar disc by the binary motion of the system, implying a physical link between ULX pulsars and high-mass X-ray binary (HMXB) pulsars. This hypothesis is supported by recent studies of Galactic and Magellanic Cloud HMXBs accreting at super-Eddington rates, and the position of ULX pulsars on the spin period–orbital period diagram of HMXBs. An interesting secondary relationship discovered in this work is the apparent connection between disc-fed HMXBs, ULXs, and a seemingly unrelated group of early-type binaries showing so-called double-periodic variability. We suggest that these systems are good candidates to be the direct progenitors of Be/X-ray binaries.
1745-3925
139-143
Townsend, L.J.
b75c3b6e-ab70-4570-b388-6f24799caf74
Charles, P.A.
0429b380-0754-4dc1-8def-885c7fa6a086
Townsend, L.J.
b75c3b6e-ab70-4570-b388-6f24799caf74
Charles, P.A.
0429b380-0754-4dc1-8def-885c7fa6a086

Townsend, L.J. and Charles, P.A. (2020) Orbital and superorbital periods in ULX pulsars, disc-fed HMXBs, Be/X-ray binaries, and double-periodic variables. Monthly Notices of the Royal Astronomical Society: Letters, 495 (1), 139-143. (doi:10.1093/mnrasl/slaa078).

Record type: Article

Abstract

We present evidence for a simple linear relationship between the orbital period and superorbital period in ultra-luminous X-ray (ULX) pulsars, akin to what is seen in the population of disc-fed neutron star supergiant X-ray binary and Be/X-ray binary systems. We argue that the most likely cause of this relationship is the modulation of precessing hotspots or density waves in an accretion or circumstellar disc by the binary motion of the system, implying a physical link between ULX pulsars and high-mass X-ray binary (HMXB) pulsars. This hypothesis is supported by recent studies of Galactic and Magellanic Cloud HMXBs accreting at super-Eddington rates, and the position of ULX pulsars on the spin period–orbital period diagram of HMXBs. An interesting secondary relationship discovered in this work is the apparent connection between disc-fed HMXBs, ULXs, and a seemingly unrelated group of early-type binaries showing so-called double-periodic variability. We suggest that these systems are good candidates to be the direct progenitors of Be/X-ray binaries.

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2004.14207 - Accepted Manuscript
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Accepted/In Press date: 26 April 2020
e-pub ahead of print date: 4 May 2020
Published date: 11 June 2020

Identifiers

Local EPrints ID: 442816
URI: http://eprints.soton.ac.uk/id/eprint/442816
ISSN: 1745-3925
PURE UUID: c2fb68f1-b86d-4682-a9f8-1096af35e232

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Date deposited: 28 Jul 2020 16:31
Last modified: 06 Oct 2020 18:41

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