Title:	Torque reversals and pulse profile of the pulsar 4U 1626-67
Authors:	Beri, Aru Jain, Chetana Paul, Biswajit Raichur, Harsha
Keywords:	accretion discs
Issue Date:	1-Apr-2014
Publisher:	Oxford University Press
Citation:	Monthly Notices of the Royal Astronomical Society, 2014, Vol. 439, p1940-1947
Abstract:	We review the pulse profile evolution of the unique accretion powered X-ray pulsar 4U 1626−67 over the last 40 yr since its discovery. This pulsar showed two distinct eras of steady spin-up separated by a steady spin-down episode for about 18 yr. In this work, using data from different observatories active during each phase of spin-up and spin-down, we establish a clear correlation between the accretion torque acting on this pulsar and its pulse profile. The energy-resolved pulse profiles are identical in both the spin-up eras and quite different in the spin-down era, especially in the low-energy band. This correlation, along with the already known feature of strong quasi-periodic oscillations (QPO) that was present only in the spin-down era, clearly establishes two different accretion modes on to the neutron star which produce different pulse profiles and only one of which produces the QPOs.
Description:	Open Access
URI:	http://hdl.handle.net/2289/5959
ISSN:	0035-8711 1365-2966 - (online)
Alternative Location:	http://adsabs.harvard.edu/abs/2014MNRAS.439.1940B http://arxiv.org/abs/1401.2936 http://dx.doi.org/10.1093/mnras/stu087
Copyright:	2014 The authors & the Royal Astronomical Society.
Appears in Collections:	Research Papers (A&A)

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