BROADBAND X-RAY IMAGING AND SPECTROSCOPY OF THE CRAB NEBULA AND PULSAR WITH NuSTAR

Journal Article · Sun Mar 01 04:00:00 EST 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/801/1/66· OSTI ID:22522039

Madsen, Kristin K.; Harrison, Fiona; Grefenstette, Brian W. ^[1]; Reynolds, Stephen ^[2]; An, Hongjun ^[3]; Boggs, Steven; Craig, William W.; Zoglauer, Andreas ^[4]; Christensen, Finn E. ^[5]; Fryer, Chris L. ^[6]; Hailey, Charles J.; Nynka, Melania ^[7]; Markwardt, Craig; Zhang, William ^[8]; Stern, Daniel ^[9]

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1. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
2. Physics Department, NC State University, Raleigh, NC 27695 (United States)
3. Department of Physics, McGill University, Montreal, Quebec, H3A 2T8 (Canada)
4. Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
5. DTU Space, National Space Institute, Technical University of Denmark, Elektronvej 327, DK-2800 Lyngby (Denmark)
6. CCS-2, Los Alamos National Laboratory, Livermore, CA 94550 (United States)
7. Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
8. Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
9. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

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.

• OSTI ID: 22522039
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 801; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CRAB NEBULA
ENERGY DEPENDENCE
INDEXES
JETS
KEV RANGE
PULSARS
PULSES
STARS
X RADIATION
X-RAY SPECTROSCOPY