The Glitches of the Anomalous X‐Ray Pulsar 1RXS J170849.0−400910

Abstract

We report on a timing analysis of archival observations of the anomalous X-ray pulsar 1RXS J170849.0À400910 made with the RXTE Proportional Counter Array. We detect a new large glitch (D= ' 3 Â 10 À6 ) that occurred between 2001 March 27 and May 6, with an associated large increase in the spin-down rate (D _ = _ ' 0:3). The short time (1.5 yr) elapsed from the previously detected glitch and the large amplitude of the new spin-up place this source among the most frequent glitchers, with large average glitch amplitudes, similar to those of the Vela pulsar. The source shows different recoveries after the glitches: in the first one it is well described by a long-term linear trend similar to those seen in Vela-like glitches; in the second case the recovery is considerably faster and is better described by an exponential plus a fractional change in the long-term spin-down rate of the order of 1%. No recovery of the latter is detected, but additional observations are necessary to confirm this result. We find minor but significant changes in the average pulse profile after both glitches. No bursts were detected in any light curve, but our search was limited in sensitivity with respect to short (t < 60 ms) bursts. Observed glitch properties are compared to those of radio pulsar glitches; current models are discussed in light of our results. It appears that glitches may represent yet another peculiarity of anomalous X-ray pulsars. Starquake-based models appear to be preferred on qualitative grounds. Alternative models can be applied to individual glitches but fail in explaining both. Thus the two events may as well arise from two different mechanisms.

X-ray intensity-hardness correlation and deep IR observations of the anomalous X-ray pulsar 1RXS J170849-400910

“…A period search led to a clear detection of the neutron star spin period at P = 11.0027 ± 0.0003 s, derived with a phase fitting techniques. This period is consistent with the extrapolation from known ephemerides at a constant period derivative Dall'Osso et al 2003). We found a PF of 31 ± 2%, 39 ± 3%, 29 ± 4% and 35 ± 7% in the 0.2-10 keV, 0.2-2 keV, 2-4 keV and 4-10 keV energy bands, respectively.…”

A Comprehensive Study of the X‐Ray Bursts from the Magnetar Candidate 1E 2259+586

“…We make the admittedly speculative assumption that all such outbursts are accompanied by comparably sized glitches. A comparable glitch in the AXP 1RXS 1708À4009 was recently detected in 5.4 yr of monitoring without evidence of radiative outburst; however, the sparse observations could have missed one Dall'Osso et al 2003). Two small bursts have been seen in 6.8 yr of timing of the AXP 1E 1048.1À5937 ; all the measured properties of these two bursts fall within the range of burst properties found for 1E 2259+586.…”

Bayesian timing analysis of giant flare of SGR 180620 by RXTE PCA

“…We estimated frequency centroids and full widths at half maximums. For significant detections they are presented in Table 1 For those significant detections, we also fitted folded light curves with a template function, ψ(t) = n i=1 A i sin[iω 0 (t − ψ i )], truncating the series at the highest harmonic that was statistically significant after performing an F-test (see Dall'Osso et al 2003, for details). It turned out that oscillations at 16.9 Hz and 36.8 Hz, adding the second harmonic does not improve the fit of the phase-folded light curve (signifcance levels, accordingly are 0.71 and 0.16), while in the case of 21.3 Hz it significantly improves it (significance level of 0.0006.…”