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http://hdl.handle.net/2289/4947
Title: | Detection of pulsating soft X-ray excess in the Magellanic Cloud pulsars with ASCA |
Authors: | Paul, Biswajit Yokogawa, J. Nishiuchi, M. Endo, T. Dotani, T. Nagase, F. |
Issue Date: | Jan-2001 |
Publisher: | Elsevier B.V. |
Citation: | Advances in Space Research, 2001, Vol. 28, p399-403 |
Abstract: | The binary X-ray pulsars which are away from the galactic plane and therefore experience less interstellar absorption, show the presence of a soft component in the spectrum which is often described as a black-body and/or thermal bremsstrahlung emission. A thermal component for the soft excess provides a satisfactory model in the Galactic sources like Her X-1 and 4U 1626-67. But for the pulsars in the Magellanic Clouds for which the distance is of the order of 60 kpc and the luminosity is close to the Eddington limit, a soft component dominating in the lower energy part of the spectrum requires emission region which is a few orders of magnitude larger than the size of a neutron star. Using ASCA observations, we show that a pulsating nature of the soft component in several bright pulsars is difficult to explain if a thermal origin is assumed for the low energy part of the spectrum. We investigate whether a two component power-law with different absorptions or an inversely broken power-law can instead explain the pulsations at low energy. A soft power-law component may also be a common feature of the binary X-ray pulsars, which is difficult to observe because most of the sources are in the galactic plane and experience large interstellar absorption. |
Description: | Restricted Access |
URI: | http://hdl.handle.net/2289/4947 |
ISSN: | 0273-1177 |
Alternative Location: | http://adsabs.harvard.edu/abs/2001AdSpR..28..399P http://dx.doi.org/10.1016/S0273-1177(01)00438-0 |
Copyright: | 2001 Elsevier B.V. |
Appears in Collections: | Research Papers (A&A) |
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