Timing studies on RXTE observations of SAX J2103.5+4545


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Baykal A. , Inam S. C. , Stark M. J. , Heffner C. M. , Erkoca A. E. , Swank J. H.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, vol.374, no.3, pp.1108-1114, 2007 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 374 Issue: 3
  • Publication Date: 2007
  • Doi Number: 10.1111/j.1365-2966.2006.11231.x
  • Title of Journal : MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
  • Page Numbers: pp.1108-1114
  • Keywords: accretion, accretion discs, stars : neutron, pulsars : individual : SAX J2103.5+4545, X-rays : binaries, X-RAY SOURCES, MAGNETIZED NEUTRON-STARS, PULSAR SAX-J2103.5+4545, LUMINOSITY DEPENDENCE, ACCRETING PULSARS, DISCOVERY, TORQUE, ORBIT, EXO-2030+375, SPECTRA

Abstract

SAX J2103.5+4545 has been continuously monitored for similar to 900 d by the Rossi X-ray Timing Explorer (RXTE) since its outburst in 2002 July. Using these observations and previous archival RXTE observations of SAX J2103.5+4545, we refined the binary orbital parameters and find the new orbital period as P = (12.665 36 +/- 0.000 88) d and the eccentricity as 0.4055 +/- 0.0032. With these new orbital parameters, we constructed the pulse frequency and pulse frequency derivative histories of the pulsar and confirmed the correlation between X-ray flux and pulse frequency derivative presented by Baykal, Stark & Swank. We constructed the power spectra for the fluctuations of pulse frequency derivatives and found that the power-law index of the noise spectra is 2.13 +/- 0.6. The power-law index is consistent with random walk in pulse frequency derivative and is the steepest among the HMXRBs. X-ray spectra analysis confirmed the inverse correlation trend between power-law index and X-ray flux found by Baykal et al.