Propeller states in locally supercritical ULXs
Propeller states in locally supercritical ULXs
An expected signature of the presence of neutron stars in the population of ultraluminous X-ray sources (ULXs) are large scale changes in X-ray luminosity, as systems reach spin equilibrium and a propeller state ensues. We explore the predicted luminosity changes when the disc is locally supercritical, finding that a significant parameter space in dipole field strength, and accretion rate (at large radius) can be accompanied by changes of less than an order of magnitude in luminosity. We discuss the spectral signature and locate three ULXs (IC 342 X-1, Cir ULX-5, and NGC 1313 X-1), which appear to show changes consistent with the super-Eddington systems entering a propeller state, and place rough constraints on the dipole field strength of NGC 1313 X-1 of < 1010 G. This work implies that the most reliable means by which to search for putative propeller states will be to search for changes in hardness ratio and at high energies.
astro-ph.HE
2224–2234
Middleton, M.
f307c8d1-778f-499d-aa6f-70d19c2f16ab
Gurpide, A.
97591ff3-cd37-41e9-8dd1-a818fa382092
Walton, D.J.
69b75b0b-39a3-49d9-955a-715629ca9bec
1 February 2023
Middleton, M.
f307c8d1-778f-499d-aa6f-70d19c2f16ab
Gurpide, A.
97591ff3-cd37-41e9-8dd1-a818fa382092
Walton, D.J.
69b75b0b-39a3-49d9-955a-715629ca9bec
Middleton, M., Gurpide, A. and Walton, D.J.
(2023)
Propeller states in locally supercritical ULXs.
Monthly Notices of the Royal Astronomical Society, 519 (2), .
(doi:10.48550/arXiv.2211.13758).
Abstract
An expected signature of the presence of neutron stars in the population of ultraluminous X-ray sources (ULXs) are large scale changes in X-ray luminosity, as systems reach spin equilibrium and a propeller state ensues. We explore the predicted luminosity changes when the disc is locally supercritical, finding that a significant parameter space in dipole field strength, and accretion rate (at large radius) can be accompanied by changes of less than an order of magnitude in luminosity. We discuss the spectral signature and locate three ULXs (IC 342 X-1, Cir ULX-5, and NGC 1313 X-1), which appear to show changes consistent with the super-Eddington systems entering a propeller state, and place rough constraints on the dipole field strength of NGC 1313 X-1 of < 1010 G. This work implies that the most reliable means by which to search for putative propeller states will be to search for changes in hardness ratio and at high energies.
Text
2211.13758v1
- Author's Original
Text
Propeller states in locally super critical ULXs
- Accepted Manuscript
More information
Accepted/In Press date: 15 November 2022
e-pub ahead of print date: 21 December 2022
Published date: 1 February 2023
Additional Information:
Funding: MM and AG acknowledge support via STFC Consolidated grant (ST/V001000/1).
Keywords:
astro-ph.HE
Identifiers
Local EPrints ID: 474326
URI: http://eprints.soton.ac.uk/id/eprint/474326
ISSN: 1365-2966
PURE UUID: 3247d085-710d-4a85-a2d8-65fef54edc9e
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Date deposited: 20 Feb 2023 17:40
Last modified: 17 Mar 2024 00:58
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Author:
M. Middleton
Author:
A. Gurpide
Author:
D.J. Walton
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