Temperature Profiles of Accretion Disks around Rapidly Rotating Neutron Stars in General Relativity and Implications for Cygnus X-2

Bhattacharyya, Sudip and Thampan, Arun V and Misra, Ranjeev and Datta, Bhaskar (2000) Temperature Profiles of Accretion Disks around Rapidly Rotating Neutron Stars in General Relativity and Implications for Cygnus X-2. In: Astrophysical Journal, 542 (01). pp. 473-483.

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Abstract

We calculate the temperature profiles of (thin) accretion disks around rapidly rotating neutron stars (with low surface magnetic fields), taking into account the full effects of general relativity. We then consider a model for the spectrum of the X-ray emission from the disk that is parameterized by the mass accretion rate, the color temperature, and the rotation rate of the neutron star. We derive constraints on these parameters for the X-ray source Cygnus X-2 using the estimates of the maximum temperature in the disk along with the disk and boundary layer luminosities, using the spectrum inferred from the EXOSAT data. Our calculations suggest that the neutron star in Cygnus X-2 rotates close to the centrifugal mass-shed limit. Possible constraints on the neutron star equation of state are also discussed.

Item Type:	Journal Article
Publication:	Astrophysical Journal
Publisher:	University of Chicago Press
Additional Information:	Copyright of this article belongs to University of Chicago Press.
Department/Centre:	Division of Physical & Mathematical Sciences > Joint Astronomy Programme
Date Deposited:	19 Nov 2009 05:48
Last Modified:	19 Sep 2010 05:00
URI:	http://eprints.iisc.ac.in/id/eprint/18268

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