Repeated, Delayed Torque Variations Following X-Ray Flux Enhancements in the Magnetar 1E 1048.1-5937
Abstract
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 \dot{ν } 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2015
- DOI:
- 10.1088/0004-637X/800/1/33
- arXiv:
- arXiv:1412.2780
- Bibcode:
- 2015ApJ...800...33A
- Keywords:
-
- pulsars: general;
- pulsars: individual: 1E 1048.1-5937;
- stars: neutron;
- X-rays: stars;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Submitted to ApJ. 10 pages, 7 figures