Timing and X-ray Spectral Features of Swift J1626.6-5156

In this paper, we extend timing analysis of Baykal et al. (2010) of \src using RXTE-PCA observations between MJD 53724 and MJD 55113 together with a Chandra-ACIS observation on MJD 54897 with a 20 ks exposure. We also present X-ray spectral analysis of these RXTE and Chandra observations. We find that the spin-up rate of the source is correlated with the X-ray flux. Using this correlation, we estimate the distance and surface magnetic field of the source as $\sim 15$kpc and $\sim 9\times 10^{11}$Gauss respectively. From the spectral analysis, we found that power law index increases and Hydrogen column density decreases with decreasing flux.Comment: Revised version; 12 pages, 4 figures, accepted for publication in MNRA

Pulse Profiles of Swift J1626.6+5156

In this paper, we analyzed pulse profiles of Swift J1626.6+5156 using the lightcurves from RXTE-PCA observations between MJD 53724 (just after the outburst) and MJD 55113 and a Chandra-ACIS dataset on MJD 54897 with a 20 ks exposure. We found that pulse profiles show morphological variations and pulsations do not cease even $\sim 1200$ days after the outburst. Despite these variations, we did not find any significant variation in the pulsed fraction with decreasing X-ray flux.Comment: 4 pages, 2 figures, Conference proceeding of "Astrophysics of Neutron Stars 2010 -- a conference in honor of M. Ali Alpar", 2-6 August 2010, Cesme, Izmir, Turke

RXTE timing analysis of the anomalous X-ray pulsar 1E 2259+586

We present a pulse-timing analysis of Rossi X-ray Timing Explorer (RXTE) observations of the anomalous X-ray pulsar 1E 2259+586 from its 2002 outburst to 2010 October. We have the following objectives: to extend the work on the recovery stage after the 2002 glitch; to investigate the variations caused by the second glitch that occurred in 2007; to look for other unusual events, if any, that arise in the regular spin-down trend of the source. We find that the fractional change in the spin frequency derivative after the 2002 glitch is not stable as it decreased by an order of magnitude, from -2.2 x 10(-2) to -1.278(3) x 10-3, in about 2.5 yr. Using a pulse-timing analysis, we discover two small frequency shifts with fractional changes Delta v/v= 3.08(32) x 10(-8) and Delta v/v=-1.39(11) x 10(-8). While the first of these shifts is not found to have a fractional frequency derivative change, the second has . We interpret these frequency changes as positive and negative microglitches, similar to those seen in radio pulsars