학술논문
Observational properties of accreting neutron stars with an optically thick envelope.
Document Type
Article
Author
Source
Subject
*X-ray spectra
*ACCRETION (Astrophysics)
*EDDINGTON mass limit
*SOFT X rays
*NEUTRON stars
*RADIATIVE transfer
*X-ray binaries
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Language
ISSN
0035-8711
Abstract
Pulsating ultraluminous X-ray sources are thought to be X-ray bright, accreting, magnetized neutron stars. Their measured soft (<20 keV) X-ray luminosity can exceed the Eddington luminosity for a neutron star by a few orders of magnitude. Although several scenarios have been proposed to explain the different components observed in the X-ray spectrum and the characteristics of the X-ray pulse profile of these systems, detailed quantitative calculations are still missing. In particular, the observed soft X-ray pulse profiles are almost sinusoidal and show an increase in the pulsed fraction (from 8 up to even 30 per cent) with increasing energy. In this work, we discuss how emission originating from an optically thick envelope, expected to be formed during super-Eddington accretion, can match the observed spectra and pulse profiles. [ABSTRACT FROM AUTHOR]