A comprehensive study of RXTE and INTEGRAL observations of the X-ray pulsar 4U 1907+09

Sahiner, S.
Baykal, Altan
We analyse observations of the accretion-powered pulsar 4U 1907+09 from the International Gamma-Ray Astrophysics Laboratory (INTEGRAL; between 2005 October and 2007 November) and from the Rossi X-ray Timing Explorer (RXTE; between 2007 June and 2011 March). Using observations from the Imager on-board the INTEGRAL satellite (IBIS), the INTEGRAL Soft Gamma-Ray Imager (ISGRI) and the RXTE Proportional Counter Array (PCA), we update the pulse period history of the source. We construct power spectrum density of pulse frequencies, and we find that fluctuations in the pulse frequency derivatives are consistent with the random walk model with a noise strength of 1.27 x 10(-21) Hz s-2. From the X-ray spectral analysis of RXTE/PCA observations, we find that the hydrogen column density is variable over the binary orbit, and that it tends to increase just after the periastron passage. We also show that the X-ray spectrum becomes hardened with decreasing X-ray flux. We discuss the pulse-to-pulse variability of the source near dipping ingress and egress. We find that the source is more likely to undergo dipping states after apastron until periastron when the accretion from clumpy wind might dominate. Thus, occasional transitions to a temporary propeller state might occur.


A study of temeporal characteristics of selected Cataclysmic Variables: The broad-band noise structure between 2-20 kev
Balman, Şölen; Kulebi, B; Beklen, E (2005-09-30)
We present the preliminary analysis of the band-limited noise structure of Cataclysmic Variables (CVs) in the 220 keV energy band. We have currently analyzed Rossi X-ray Timing Explorer (RXTE) PCA data and derived time series from 30 CVs using the RXTE archive. In general, CVs of different types all show broad band noise which can be fitted with power laws, using exponential cut-offs, and Lorenzians in a similar way to power spectral (noise) characteristics of X-ray Binaries (XRBs). In general terms the pow...
Discovery of a glitch in the accretion- powered pulsar SXP 1062
Serim, Muhammed Miraç; Sahiner, S.; Cerri-Serim, D.; İNAM, SITKI ÇAĞDAŞ; Baykal, Altan (2017-11-01)
We present timing analysis of the accretion-powered pulsar SXP 1062, based on the observations of Swift, XMM-Newton and Chandra satellites covering a time span of about 2 yr. We obtain a phase coherent timing solution that shows that SXP 1062 has been steadily spinning down with a rate-4.29(7) x10(-14) Hz s(-1) leading to a surface magnetic field estimate of about 1.5 x 10(14) G. We also resolve the binary orbital motion of the system from X-ray data that confirms an orbital period of 656(2) d. On MJD 56834...
A study of selected low-mass X-ray binary dip sources observed with INTEGRAL
Balman, Şölen (2007-08-17)
I present archival data of the dipping LMXB systems, XB 1916-053, XB 1323-619, X1624-490, and 4U 1746-371obtained by the ISGRI and JEM-X detectors on-board the INTEGRAL Observatory. The spectral parameters derived from the fits to the data are consistent with hot coronal regions in these systems where the electron temperatures are in a range 4.9-18.8 keV with the exception of XB 1323-62 having an unbounded temperature. The optical depth to Compton scattering, tau is low and consistent with electron densitie...
Recent torque reversal of 4U 1907+09
İnam, S. Ç.; Şahiner, Ş.; Baykal, Altan (Oxford University Press (OUP), 2009-5-11)
We present timing and spectral analysis of RXTE-PCA ( Proportional Counter Array) observations of the accretion powered pulsar 4U 1907+09 between 2007 June and 2008 August. 4U 1907+09 had been in a spin-down episode with a spin-down rate of -3.54 x 10(-14) Hz s(-1) before 1999. From RXTE observations after 2001 March, the source showed a similar to 60 per cent decrease in spin-down magnitude, and INTEGRAL observations after 2003 March showed that source started to spin-up. We found that the source recently ...
Short-term pulse frequency fluctuations of OAO 1657-415 from RXTE observations
Baykal, Altan (2000-04-11)
We present new X-ray observations of the high-mass X-ray binary (HMXRB) pulsar OAO 1657-415, obtained during one orbital period (10.44 d) with the Rossi X-Ray Timing Explorer (RXTE). Using the binary orbital parameters, obtained from Burst and Transient Source Experiment (BATSE) observations, we resolve the fluctuations in the pulse frequency at time-scales on the order of 1 d for the first time. Recent BATSE results by Baykal showed that OAO 1657-415 has spin-up/down trends in its pulse frequency time seri...
Citation Formats
S. Sahiner, S. Ç. İNAM, and A. Baykal, “A comprehensive study of RXTE and INTEGRAL observations of the X-ray pulsar 4U 1907+09,” MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, pp. 2079–2087, 2012, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/45937.