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X-ray Bursts from the Transient Magnetar Candidate XTE J1810-197

P. M. Woods·C. Kouveliotou·F. P. Gavriil·V. M. Kaspi·M. S. E. Roberts·A. Ibrahim·C. B. Markwardt·J. H. Swank·M. H. Finger
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Abstract

We have discovered four X-ray bursts, recorded with the Rossi X-ray Timing Explorer Proportional Counter Array between 2003 September and 2004 April, that we show to originate from the transient magnetar candidate XTE J1810-197. The burst morphologies consist of a short spike or multiple spikes lasting ~1 s each followed by extended tails of emission where the pulsed flux from XTE J1810-197 is significantly higher. The burst spikes are likely correlated with the pulse maxima, having a chance probability of a random phase distribution of 0.4%. The burst spectra are best fit to a blackbody with temperatures 4-8 keV, considerably harder than the persistent X-ray emission. During the X-ray tails following these bursts, the temperature rapidly cools as the flux declines, maintaining a constant emitting radius after the initial burst peak. During the brightest X-ray tail, we detect a narrow emission line at 12.6 keV with an equivalent width of 1.4 keV and a probability of chance occurrence less than 4 x 10^-6. The temporal and spectral characteristics of these bursts closely resemble the bursts seen from 1E 1048.1-5937 and a subset of the bursts detected from 1E 2259+586, thus establishing XTE J1810-197 as a magnetar candidate. The bursts detected from these three objects are sufficiently similar to one another, yet significantly different from those seen from soft gamma repeaters, that they likely represent a new class of bursts from magnetar candidates exclusive (thus far) to the anomalous X-ray pulsar-like sources.

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P. M. Woods, C. Kouveliotou, F. P. Gavriil, V. M. Kaspi, M. S. E. Roberts, A. Ibrahim, C. B. Markwardt, J. H. Swank, M. H. Finger. 2005-05-02. X-ray Bursts from the Transient Magnetar Candidate XTE J1810-197. https://doi.org/10.1086/431476

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