Analysis of RXTE-PCA Observations of SMC X-1

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İNAM S. Ç. , BAYKAL A., Beklen E.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, vol.403, no.1, pp.378-386, 2010 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 403 Issue: 1
  • Publication Date: 2010
  • Doi Number: 10.1111/j.1365-2966.2009.16121.x
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.378-386
  • Keywords: accretion, accretion discs, stars: neutron, pulsars: individual: SMC X-1, X-rays: binaries, X-RAY PULSAR, SMALL-MAGELLANIC-CLOUD, SPIN-UP RATE, ORBITAL PERIOD, LOW STATE, SMC-X-1, ACCRETION, DISCOVERY, HERCULES-X-1, VARIABILITY


We present timing and spectral analysis of Rossi X-ray Timing Explorer-Proportional Counter Array observations of SMCX-1 between 1996 January and 2003 December. From observations around 1996 August 30 with a time-span of similar to 6 d, we obtain a precise timing solution for the source and resolve the eccentricity as 0.00089(6). We find an orbital decay rate of (P) over dot(orb)/P(orb) = -3.402(7) x 10(-6) yr(-1) which is close to the previous results. Using our timing analysis and the previous studies, we construct a similar to 30 yr long pulse period history of the source. We show that frequency derivative shows long- (i.e. more than a few years) and short-term (i.e. order of days) fluctuations. From the spectral analysis, we found that all spectral parameters except Hydrogen column density showed no significant variation with time and X-ray flux. Hydrogen column density is found to be higher as X-ray flux gets lower. This may be due to the increase in soft absorption when the pulsar is partially obscured as in Her X-1 or may just be an artefact of the tail of a soft excess in energy spectrum.