Phase-resolved NuSTAR and Swift-XRT observations of magnetar 4U 0142+61

Journal Article · Mon Jul 20 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/808/1/32· OSTI ID:22882796

Tendulkar, Shriharsh P.; Harrison, Fiona A. ^[1]; Hascöet, Romain; Beloborodov, Andrei M.; Hailey, Charles A. ^[2]; Yang, Chengwei ^[3]; Kaspi, Victoria M.; Guillot, Sebastien ^[4]; An, Hongjun ^[5]; Bachetti, Matteo ^[6]; Boggs, Steven E. ^[7]; Christensen, Finn E.; Craig, William W. ^[8]; Stern, Daniel ^[9]; Zhang, William ^[10]

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1. Space Radiation Laboratory, California Institute of Technology, 1200 E California Blvd, MC 249-17, Pasadena, CA 91125 (United States)
2. Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
3. Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081 (China)
4. Department of Physics, McGill University, Montreal, Quebec, H3A 2T8 (Canada)
5. Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States)
6. INAF/Osservatorio Astronomico di Cagliari, via della Scienza 5, I-09047 Selargius (Italy)
7. Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
8. DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)
9. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
10. NASA Goddard Space Flight Center, Astrophysics Science Division, Code 661, Greenbelt, MD 20771 (United States)

We present temporal and spectral analysis of simultaneous 0.5–79 keV Swift-XRT and Nuclear Spectroscopic Telescope Array observations of the magnetar 4U 0142+61. The pulse profile changes significantly with photon energy between 3 and 35 keV. The pulse fraction increases with energy, reaching a value of ≈20%, similar to that observed in 1E 1841–045 and much lower than the ≈80% pulse fraction observed in 1E 2259+586. We do not detect the 55 ks phase modulation reported in previous Suzaku-HXD observations. The phase-averaged spectrum of 4U 0142+61 above 20 keV is dominated by a hard power law (PL) with a photon index Γ{sub H}∼0.65, and the spectrum below 20 keV can be described by two blackbodies, a blackbody plus a soft PL, or by a Comptonized blackbody model. We study the full phase-resolved spectra using the e{sup ±} outflow model of Beloborodov. Our results are consistent with the parameters of the active j-bundle derived from INTEGRAL data by Hascoët et al. We find that a significant degeneracy appears in the inferred parameters if the footprint of the j-bundle is allowed to be a thin ring instead of a polar cap. The degeneracy is reduced when the footprint is required to be the hot spot inferred from the soft X-ray data.

• OSTI ID: 22882796
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 808; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
HOT SPOTS
NEUTRON STARS
PULSARS
PULSES
SOFT X RADIATION
SPECTRA
TELESCOPES