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Title: NuSTAR OBSERVATIONS OF MAGNETAR 1E 1048.1–5937

We report on simultaneous Nuclear Spectroscopic Telescope Array (NuSTAR) and XMM-Newton observations of the magnetar 1E 1048.1-5937, along with Rossi X-ray Timing Explorer (RXTE) data for the same source. The NuSTAR data provide a clear detection of this magnetar’s persistent emission up to 20 keV. We detect a previously unreported small secondary peak in the average pulse profile in the 7–10 keV band, which grows to an amplitude comparable to that of the main peak in the 10–20 keV band. We show using RXTE data that this secondary peak is likely transient. We find that the pulsed fraction increases with energy from a value of ~0.55 at ~2 keV to a value of ~0.75 near 8 keV but shows evidence of decreasing at higher energies. After filtering out multiple bright X-ray bursts during the observation, we find that the phase-averaged spectrum from combined NuSTAR and XMM data is well described by an absorbed double blackbody plus power-law model, with no evidence for the spectral turn-up near ~10 keV as has been seen in some other magnetars. Our data allow us to rule out a spectral turn-up similar to those seen in magnetars 4U 0142+61 and 1E 2259+586 of ΔΓ≳2, wheremore » ΔΓ is the difference between the softband and hard-band photon indexes. The lack of spectral turn-up is consistent with what has been observed from an active subset of magnetars given previously reported trends suggesting that the degree of spectral turn-up is correlated with spin-down rate and/or spin-inferred magnetic field.« less
Authors:
 [1] ; ORCiD logo [2] ;  [3] ; ORCiD logo [4] ; ORCiD logo [2] ; ORCiD logo [5] ;  [6] ;  [3]
  1. Beijing Inst. of Technology (China); McGill Univ., Montreal, QC (Canada)
  2. McGill Univ., Montreal, QC (Canada)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Stanford Univ., CA (United States)
  5. Pontifica Univ. Catolica De Chile, Santiago (Chile)
  6. Columbia Univ., New York, NY (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-678161
Journal ID: ISSN 1538-4357; TRN: US1701314
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 831; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Pulsars; Magnetars
OSTI Identifier:
1343044