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Title: REPEATED, DELAYED TORQUE VARIATIONS FOLLOWING X-RAY FLUX ENHANCEMENTS IN THE MAGNETAR 1E 1048.1–5937

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 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.
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada)
  2. Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong)
  3. Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)
  4. Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  5. Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States)
Publication Date:
OSTI Identifier:
22364250
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 800; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; KEV RANGE; MAGNETIC STARS; MONITORING; NEUTRON STARS; NEUTRONS; ORIGIN; PERIODICITY; PULSARS; SPIN; STAR EVOLUTION; STARS; TELESCOPES; TORQUE; X RADIATION