Phase Variation in the Pulse Profile of SMC X-1
arXiv:astro-ph/0410495 · doi:10.1086/426890
Abstract
We present the results of timing and spectral analysis of X-ray high state observations of the high-mass X-ray pulsar SMC X-1 with Chandra, XMM-Newton, and ROSAT, taken between 1991 and 2001. The source has L_X ~ 3-5 x 10^38 ergs/s, and the spectra can be modeled as a power law plus blackbody with kT_BB \~ 0.18 keV and reprocessed emission radius R_BB ~ 2 x 10^8 cm, assuming a distance of 60 kpc to the source. Energy-resolved pulse profiles show several distinct forms, more than half of which include a second pulse in the soft profile, previously documented only in hard energies. We also detect significant variation in the phase shift between hard and soft pulses, as has recently been reported in Her X-1. We suggest an explanation for the observed characteristics of the soft pulses in terms of precession of the accretion disk.
4 pages, 4 figures, accepted for publication in ApJL; v2 minor corrections, as will appear in ApJL
References in corpus (5)
- Origin of the Soft Excess in X-ray Pulsars
- Long-term Properties of Accretion Disks in X-ray Binaries: I. the variable third period in SMC X-1
- XMM-Newton EPIC observations of Her X-1
- BeppoSAX observations of the accretion-powered X-ray pulsar SMC X-1
- XMM-Newton EPIC & OM observations of Her X-1 over the 35 day beat period
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- A New Possible Accretion Scenario for Ultra-Luminous X-ray Sources
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- Monitoring Observations of SMC X-1's Excursions (MOOSE) I: Program Description and Initial High-State Spectral Results
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