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Title: NuSTAR observations of X-ray bursts from the magnetar 1E 1048.1–5937

We report the detection of eight bright X-ray bursts from the 6.5 s magnetar 1E 1048.1–5937, during a 2013 July observation campaign with the Nuclear Spectroscopic Telescope Array. We study the morphological and spectral properties of these bursts and their evolution with time. The bursts resulted in count rate increases by orders of magnitude, sometimes limited by the detector dead time, and showed blackbody spectra with kT ∼ 6-8 keV in the T{sub 90} duration of 1-4 s, similar to earlier bursts detected from the source. We find that the spectra during the tail of the bursts can be modeled with an absorbed blackbody with temperature decreasing with flux. The burst flux decays followed a power law of index 0.8-0.9. In the burst tail spectra, we detect a ∼13 keV emission feature, similar to those reported in previous bursts from this source as well as from other magnetars observed with the Rossi X-ray Timing Explorer. We explore possible origins of the spectral feature such as proton cyclotron emission, which implies a magnetic field strength of B ∼ 2 × 10{sup 15} G in the emission region. However, the consistency of the energy of the feature in different objects requires furthermore » explanation.« less
Authors:
; ;  [1] ; ; ; ;  [2] ;  [3] ; ;  [4] ;  [5] ; ; ;  [6] ;  [7] ;  [8]
  1. Department of Physics, McGill University, Montreal, Quebec, H3A 2T8 (Canada)
  2. Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
  3. Space Science Office, ZP12, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)
  4. Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
  5. DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)
  6. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
  7. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
  8. Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
Publication Date:
OSTI Identifier:
22365567
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 790; 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; COSMIC X-RAY BURSTS; COUNTING RATES; CYCLOTRONS; DECAY; EMISSION; EVOLUTION; KEV RANGE; MAGNETIC FIELDS; NEUTRON STARS; NEUTRONS; PROTONS; PULSARS; SPECTRA; STARS; TELESCOPES; X RADIATION