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NuSTAR Study of Hard X-Ray Morphology and Spectroscopy of PWN G21.5–0.9

Nynka, Melania and Hailey, Charles J. and Reynolds, Stephen P. and An, Hongjun and Baganoff, Frederick K. and Boggs, Steven E. and Christensen, Finn E. and Craig, William W. and Gotthelf, Eric V. and Grefenstette, Brian W. and Harrison, Fiona A. and Krivonos, Roman and Madsen, Kristin K. and Mori, Kaya and Perez, Kerstin M. and Stern, Daniel and Wik, Daniel R. and Zhang, William W. and Zoglauer, Andreas (2014) NuSTAR Study of Hard X-Ray Morphology and Spectroscopy of PWN G21.5–0.9. Astrophysical Journal, 789 (1). Art. No. 72. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20140724-081931132

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Abstract

We present NuSTAR high-energy X-ray observations of the pulsar wind nebula (PWN)/supernova remnant G21.5−0.9. We detect integrated emission from the nebula up to ~40 keV, and resolve individual spatial features over a broad X-ray band for the first time. The morphology seen by NuSTAR agrees well with that seen by XMM-Newton and Chandra below 10 keV. At high energies, NuSTAR clearly detects non-thermal emission up to ~20 keV that extends along the eastern and northern rim of the supernova shell. The broadband images clearly demonstrate that X-ray emission from the North Spur and Eastern Limb results predominantly from non-thermal processes. We detect a break in the spatially integrated X-ray spectrum at ~9 keV that cannot be reproduced by current spectral energy distribution models, implying either a more complex electron injection spectrum or an additional process such as diffusion compared to what has been considered in previous work. We use spatially resolved maps to derive an energy-dependent cooling length scale, L(E)∝E^(m) with m = −0.21 ± 0.01. We find this to be inconsistent with the model for the morphological evolution with energy described by Kennel & Coroniti. This value, along with the observed steepening in power-law index between radio and X-ray, can be quantitatively explained as an energy-loss spectral break in the simple scaling model of Reynolds, assuming particle advection dominates over diffusion. This interpretation requires a substantial departure from spherical magnetohydrodynamic, magnetic-flux-conserving outflow, most plausibly in the form of turbulent magnetic-field amplification.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0004-637X/789/1/72DOIArticle
http://iopscience.iop.org/0004-637X/789/1/72/articlePublisherArticle
http://arxiv.org/abs/1405.3239arXivDiscussion Paper
ORCID:
AuthorORCID
Boggs, Steven E.0000-0001-9567-4224
Harrison, Fiona A.0000-0003-2992-8024
Krivonos, Roman0000-0003-2737-5673
Madsen, Kristin K.0000-0003-1252-4891
Mori, Kaya0000-0002-9709-5389
Stern, Daniel0000-0003-2686-9241
Additional Information:© 2014 The American Astronomical Society. Received 2013 November 11; accepted 2014 April 29; published 2014 June 17. 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 theASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA).
Group:NuSTAR, Space Radiation Laboratory
Subject Keywords:ISM: individual objects (G21.5–0.9); ISM: supernova remnants; radiation mechanisms: general; stars: neutron; X-rays: ISM
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2014-48
Record Number:CaltechAUTHORS:20140724-081931132
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140724-081931132
Official Citation:NuSTAR Study of Hard X-Ray Morphology and Spectroscopy of PWN G21.5–0.9 Melania Nynka et al. 2014 ApJ 789 72
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47453
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:24 Jul 2014 21:29
Last Modified:10 Oct 2017 21:07

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