Phase-resolved NuSTAR and Swift-XRT Observations of Magnetar 4U 0142+61
Abstract
We present temporal and spectral analysis of simultaneous 0.5-79 keV Swift-XRT and NuSTAR 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 with a photon index, Γ ~ 0.65, and the spectrum below 20 keV can be described by two blackbodies, a blackbody plus a soft power law, or by a Comptonized blackbody model. We study the full phase-resolved spectra using the electron-positron outflow model of Beloborodov (2013). Our results are consistent with the parameters of the active j-bundle derived from INTEGRAL data by Hascoet et al. (2014). 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.
Additional Information
© 2015 American Astronomical Society. Received 2015 April 24; accepted 2015 June 8; published 2015 July 16. This work was supported under NASA Contract No. NNG08FD60C, and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). V.M.K. acknowledges support from an NSERC Discovery Grant and Accelerator Supplement, the FQRNT Centre de Recherche Astrophysique du Québec, an R. Howard Webster Foundation Fellowship from the Canadian Institute for Advanced Research (CIFAR), the Canada Research Chairs Program and the Lorne Trottier Chair in Astrophysics and Cosmology.Attached Files
Published - 0004-637X_808_1_32.pdf
Submitted - 1506.03098v1.pdf
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Additional details
- Eprint ID
- 58224
- Resolver ID
- CaltechAUTHORS:20150615-051918365
- NASA
- NNG08FD60C
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- Fonds Québécois de la Recherche sur la Nature et les Technologies (FQRNT)
- Canadian Institute for Advanced Research (CIFAR)
- Canadian Research Chairs Program
- Lorne Trottier Chair in Astrophysics and Cosmology
- Created
-
2015-06-15Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- NuSTAR, Space Radiation Laboratory
- Other Numbering System Name
- Space Radiation Laboratory
- Other Numbering System Identifier
- 2015-51