Discovery of a soft spectral component and transient 22.7 second quasi-periodic oscillations of SAX J2103.5+4545

Inam, SC
Baykal, Altan
Swank, J
Stark, MJ
XMM-Newton observed SAX J2103.5+4545 on 2003 January 6, while the Rossi X-Ray Timing Explorer (RXTE) was also monitoring the source. Using the RXTE Proportional Counter Array data set between 2002 December 3 and 2003 January 29, the spin period and average spin-up rate during the XMM-Newton observations were found to be 354.7940+/-0.0008 s and (7.4+/-0.9)x10(-13) Hz s(-1), respectively. In the power spectrum of the 0.9-11 keV EPIC PN light curve, we found quasi-periodic oscillations (QPOs) around 0.044 Hz (22.7 s) with an rms fractional amplitude of similar to6.6%. We interpreted this QPO feature as the Keplerian motion of inhomogeneities through the inner disk. In the X-ray spectrum, in addition to the power-law component with high-energy cutoff and the similar to6.4 keV fluorescent iron emission line, we discovered a soft component consistent with blackbody emission with kTsimilar to1.9 keV. The pulse phase spectroscopy of the source revealed that the blackbody flux peaked at the peak of the pulse with an emission radius of similar to0.3 km, suggesting the polar cap on the neutron star surface as the source of the blackbody emission. The flux of the iron emission line at similar to6.42 keV was shown to peak at the off-pulse phase, supporting the idea that this feature arises from fluorescent emission of the circumstellar material around the neutron star rather than the hot region in the vicinity of the neutron star polar cap.


Discovery of a transient magnetar: XTE J1810-197
Ibrahim, AI; Markwardt, CB; Swank, JH; Ransom, S; Roberts, M; Kaspi, V; Woods, PM; Safi-Harb, S; Balman, Şölen; Parke, WC; Kouveliotou, C; Hurley, K; Cline, T (IOP Publishing, 2004-07-01)
We report the discovery of a new X-ray pulsar, XTE J1810 - 197, that was serendipitously discovered on 2003 July 15 by the Rossi X-Ray Timing Explorer (RXTE) while observing the soft gamma repeater SGR 1806 - 20. The pulsar has a 5.54 s spin period, a soft X-ray spectrum ( with a photon index of approximate to 4), and is detectable in earlier RXTE observations back to 2003 January but not before. These show that a transient outburst began between 2002 November 17 and 2003 January 23 and that the source's pe...
Discovery of the orbit of the transient X-ray pulsar SAX J2103.5+4545
Baykal, Altan; Swank, J (IOP Publishing, 2000-12-01)
Using X-ray data from the Rossi X-Ray Timing Explorer (RXTE), we carried out a pulse-timing analysis of the transient X-ray pulsar SAX J2103.5+4545. An outburst was detected by the All-Sky Monitor (ASM) in 1999 October 25 and reached a peak X-ray brightness of 27 mcrab on October 28. Between November 19 and December 27, the RXTE Proportional Counter Array (PCA) carried out pointed observations that provided us with pulse arrival times. These yield an eccentric orbit (e = 0.4 +/- 0.2) with an orbital period ...
Analysis of RXTE-PCA Observations of SMC X-1
İNAM, SITKI ÇAĞDAŞ; Baykal, Altan; Beklen, E. (Oxford University Press (OUP), 2010-03-21)
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...
X-ray flux related timing and spectral features of 2S 1417-62
Inam, SC; Baykal, Altan; Scott, DM; Finger, M; Swank, J (Oxford University Press (OUP), 2004-03-21)
Rossi X-ray Timing Explorer (RXTE) observations of the X-ray transient pulsar 2S 1417-62 between 1999 November and 2000 August with a total exposure of similar to394 ks have been analysed. Observations include a main outburst followed by a series of mini outbursts. Changes in pulse morphology and pulse fraction were found to be related to the changes in X-ray flux. Particularly low X-ray flux regions were found to have significantly lower pulse fractions with different pulse morphologies. The 3-60 keV Propo...
Recent X-ray measurements of the accretion-powered pulsar 4U 1907+09
in't Zand, JJM; Baykal, Altan; Strohmayer, TE (IOP Publishing, 1998-03-20)
X-ray observations of the accreting X-ray pulsar 4U 1907 + 09 obtained during 1996 February with the Proportional Counter Array onboard the Rossi X-Ray Timing Explorer (RXTE) have made possible the first measurement of the intrinsic pulse period (P-pulse) since 1984: P-pulse = 440.341(-0.017)(+0.012) s. 4U pulse 1907 + 09 is in a binary system with a blue supergiant. The orbital parameters have been solved, which enables us to correct a measurement of P-pulse obtained in 1990 with Ginga for orbital delay ef...
Citation Formats
S. Inam, A. Baykal, J. Swank, and M. Stark, “Discovery of a soft spectral component and transient 22.7 second quasi-periodic oscillations of SAX J2103.5+4545,” ASTROPHYSICAL JOURNAL, pp. 463–468, 2004, Accessed: 00, 2020. [Online]. Available: