Speaker
Robert Archibald
Description
1E 1048.1-5937 is one of the most active magnetars, having exhibited three long-term flux flares, as well as several SGR-like bursts, pulse profile changes, and timing anomalies in 16 years of previous monitoring. This pulsar has also displayed behavior not seen in any other magnetar: on the order of 100 days after the start of two of these flux flares, the spin-down rate underwent a period of greatly increased variability for the approximately two years. These bizarre episodes, in which the spin-down rate changed abruptly by a factor of as much as 10, are a significant puzzle in magnetar astrophysics and, if repeatable, suggest the slow build-up of outer magnetospheric twisting as suggested by Beloborodov (2009) . Here we report a fourth flux flare in 1E 1048.1-5937 as observed in X-ray timing observations obtained using the Swift X-ray Telescope in December 2011. We show that again roughly 100 days following the flare, the pulsar's spin-down rate began showing large variations, with the source presently being in this state. This strongly suggests that such flare/torque change delays are repeatable in this source. Why such delayed spin-down variations are seen thus far uniquely in 1E 1048.1-5937 remains puzzling.
Author
Co-authors
Dr
A. P. Beardmore
(University of Leicester,)
Dr
C.-Y. Ng
(The University of Hong Kong,)
Dr
Jamie Kennea
(Pennsylvania State University)
Dr
Neil Gehrels
(NASA Goddard Space Flight Center,)
Paul Scholz
Dr
Victoria Kaspi
(McGill)
