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Broadband x-ray imaging and spectroscopy of the Crab nebula and pulsar with NuSTAR

Madsen, Kristin K. and Reynolds, Stephen and Harrison, F. A. and An, Hongjun and Boggs, Steven and Christensen, Finn E. and Craig, William W. and Fryer, Chris L. and Grefenstette, Brian W. and Hailey, Charles J. and Markwardt, Craig B. and Nynka, Melania and Stern, Daniel and Zoglauer, Andreas and Zhang, William (2015) Broadband x-ray imaging and spectroscopy of the Crab nebula and pulsar with NuSTAR. Astrophysical Journal, 801 (1). Art. No. 66. ISSN 0004-637X. doi:10.1088/0004-637X/801/1/66.

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We present broadband (3-78 keV) NuSTAR X-ray imaging and spectroscopy of the Crab nebula and pulsar. We show that while the phase-averaged and spatially integrated nebula + pulsar spectrum is a power law in this energy band, spatially resolved spectroscopy of the nebula finds a break at ~9 keV in the spectral photon index of the torus structure with a steepening characterized by ΔΓ ~ 0.25. We also confirm a previously reported steepening in the pulsed spectrum, and quantify it with a broken power law with break energy at ~12 keV and ΔΓ ~ 0.27. We present spectral maps of the inner 100'' of the remnant and measure the size of the nebula as a function of energy in seven bands. These results find that the rate of shrinkage with energy of the torus size can be fitted by a power law with an index of γ = 0.094 ± 0.018, consistent with the predictions of Kennel and Coroniti. The change in size is more rapid in the NW direction, coinciding with the counter-jet where we find the index to be a factor of two larger. NuSTAR observed the Crab during the latter part of a γ-ray flare, but found no increase in flux in the 3-78 keV energy band.

Item Type:Article
Related URLs:
URLURL TypeDescription
Madsen, Kristin K.0000-0003-1252-4891
Harrison, F. A.0000-0003-2992-8024
Boggs, Steven0000-0001-9567-4224
Christensen, Finn E.0000-0001-5679-1946
Fryer, Chris L.0000-0003-2624-0056
Grefenstette, Brian W.0000-0002-1984-2932
Markwardt, Craig B.0000-0001-9803-3879
Nynka, Melania0000-0002-3310-1946
Stern, Daniel0000-0003-2686-9241
Zhang, William0000-0002-1426-9698
Additional Information:© 2015. The American Astronomical Society. Received 26 June 2014, accepted for publication 23 December 2014. Published 4 March 2015. 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).
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Non-Subject Keywords:pulsars: individual (Crab) – stars: neutron – X-rays: individual (Crab)
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2015-73
Issue or Number:1
Record Number:CaltechAUTHORS:20150404-114619633
Persistent URL:
Official Citation:Kristin K. Madsen et al. 2015 ApJ 801 66 doi:10.1088/0004-637X/801/1/66
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56357
Deposited By: Joy Painter
Deposited On:06 Apr 2015 15:16
Last Modified:10 Nov 2021 20:58

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