Paul Scholz, Victoria M. Kaspi
The magnetar 1E~1547$-$5408 recently exhibited two periods of outburst,
beginning on 2008 October 3 and 2009 January 22. Here we present an analysis of
the persistent radiative evolution and a statistical study of the burst
properties during the 2009 outburst using the {\em Swift} X-ray Telescope
(XRT). We find that the 1--10 keV flux increased by a factor of $\sim500$ and
hardened significantly, peaking $\sim6$ hours after the onset of the outburst.
The observed pulsed fraction exhibited an anti-correlation with phase-averaged
flux. Properties of the several hundred X-ray bursts during the 2009 outburst
were determined and compared to those from other magnetar outburst events. We
find that the peaks of the bursts occur randomly in phase but that the folded
counts that compose the bursts exhibit a pulse which is misaligned with the
persistent pulse phase. We also report a correlation between burst hardness and
flux. We compare the hardness-flux evolution of the persistent emission of both
outbursts to those from other magnetars and find that although there does exist
an overall trend, the degree of hardening for a given increase in flux is not
uniform from source to source. These results are discussed in the context of
previous results and within the magnetar model.
View original:
http://arxiv.org/abs/1106.5445
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