Title:	BeppoSAX observations of the accretion-powered X-ray pulsar SMC X-1
Authors:	Naik, S. Paul, Biswajit
Keywords:	stars: neutron stars: pulsars individual: SMC X-1 X-rays: stars
Issue Date:	May-2004
Publisher:	EDP Sciences
Citation:	Astronomy and Astrophysics, 2004, Vol.418, p655-661
Abstract:	We present here results obtained from three BeppoSAX observations of the accretion-powered X-ray pulsar SMC X-1 carried out during the declining phases of its 40-60 days long super-orbital period. Timing analysis of the data clearly shows a continuing spin-up of the neutron star. Energy-resolved timing analysis shows that the pulse-profile of SMC X-1 is single peaked at energies less than 1.0 keV whereas an additional peak, the amplitude of which increases with energy within the MECS range, is present at higher energies. Broad-band pulse-phase-averaged spectroscopy of the BeppoSAX data, which is done for the first time since its discovery, shows that the energy spectrum in the 0.1-80 keV energy band has three components, a soft excess that can be modeled as a thermal black-body, a hard power-law component with a high-energy exponential cutoff and a narrow and weak iron emission line at 6.4 keV. Pulse-phase resolved spectroscopy indicates a pulsating nature of the soft spectral component, as seen in a few other binary X-ray pulsars, with a certain phase offset with respect to the hard power-law component. Dissimilar shape and phase of the soft and hard X-ray pulse profiles suggest a different origin of the soft and hard components.
Description:	Open Access
URI:	http://hdl.handle.net/2289/4970
ISSN:	0004-6361
Alternative Location:	http://adsabs.harvard.edu/abs/2004A%26A...418..655N http://arxiv.org/abs/astro-ph/0402096 http://dx.doi.org/10.1051/0004-6361:20040048
Copyright:	2004 EDP Sciences
Appears in Collections:	Research Papers (A&A)

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