Repeated, Delayed Torque Variations Following X-ray Flux Enhancements in the Magnetar 1E  \;1048.1-5937

Dec 8, 2014
9 pages
Published in:
  • Astrophys.J. 800 (2015) 1, 33
  • Published: Feb 5, 2015
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Abstract: (IOP)
We report on two years of flux and spin evolution monitoring of 1E 1048.1–5937, a 6.5 s X-ray pulsar identified as a magnetar. Using Swift X-Ray Telescope data, we observed an X-ray outburst consisting of an increase in the persistent 1-10 keV flux by a factor of 6.3 ± 0.2, beginning on 2011 December 31 (MJD 55926). Following a delay of ~100 days, the magnetar entered a period of large torque variability, with ν˙\dot{\nu } reaching a factor of 4.55 ± 0.05 times the nominal value, before decaying in an oscillatory manner over a timescale of months. We show by comparing to previous outbursts from the source that this pattern of behavior may repeat itself with a quasi-period of ~1800 days. We compare this phenomenology to periodic torque variations in radio pulsars, finding some similarities that suggest a magnetospheric origin for the behavior of 1E 1048.1–5937.
Note:
  • Submitted to ApJ. 10 pages, 7 figures
  • pulsars: general
  • pulsars: individual (1E 1048.1-5937)
  • stars: neutron
  • X-rays: stars
  • pulsars: individual