On the magnetic fields of Be/X-ray pulsars in the Small Magellanic Cloud

Journal
Date Issued
2015
Author(s)
Ikhsanov, N. R.
•
DOI
Description
We would like to thank anonymous referee for very useful and stimulating comments. NRI thanks INAF at Milano for kind hospitality and acknowledges support of the Russian Scientific Foundation under the grant no. 14-50-00043. This work has been partially supported through financial contribution from the agreement ASI/INAF I/037/12/0 and from PRIN INAF 2014.
Abstract
We explore the possibility of explaining the properties of the Be/X-ray pulsars observed in the Small Magellanic Cloud (SMC) within the magnetic levitation accretion scenario. This implies that their X-ray emission is powered by a wind-fed accretion on to a neutron star (NS) which captures matter from a magnetized stellar wind. The NS in this case is accreting matter from a non-Keplerian magnetically levitating disc which is surrounding its magnetosphere. This allows us to explain the observed periods of the pulsars in terms of spin equilibrium without the need of invoking dipole magnetic fields outside the usual range ̃1011-1013 G inferred from cyclotron features of Galactic high-mass X-ray binaries. We find that the equilibrium period of a NS, under certain conditions, depends strongly on the magnetization of the stellar wind of its massive companion and, correspondingly, on the magnetic field of the massive companion itself. This may help to explain why similar NSs in binaries with similar properties rotate with different periods yielding a large scatter of periods of the accretion-powered pulsar observed in SMC and our galaxy.
Volume
454
Issue
4
Start page
3760
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2015MNRAS.454.3760I
Rights
open.access
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