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

Abstract

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 foundmore » no increase in flux in the 3-78 keV energy band.« less

Authors:
; ;  [1];  [2];  [3]; ; ;  [4];  [5];  [6]; ;  [7]; ;  [8];  [9]
  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)
Publication Date:
OSTI Identifier:
22522039
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 801; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CRAB NEBULA; ENERGY DEPENDENCE; INDEXES; JETS; KEV RANGE; PULSARS; PULSES; STARS; X RADIATION; X-RAY SPECTROSCOPY

Citation Formats

Madsen, Kristin K., Harrison, Fiona, Grefenstette, Brian W., Reynolds, Stephen, An, Hongjun, Boggs, Steven, Craig, William W., Zoglauer, Andreas, Christensen, Finn E., Fryer, Chris L., Hailey, Charles J., Nynka, Melania, Markwardt, Craig, Zhang, William, and Stern, Daniel. BROADBAND X-RAY IMAGING AND SPECTROSCOPY OF THE CRAB NEBULA AND PULSAR WITH NuSTAR. United States: N. p., 2015. Web. doi:10.1088/0004-637X/801/1/66.
Madsen, Kristin K., Harrison, Fiona, Grefenstette, Brian W., Reynolds, Stephen, An, Hongjun, Boggs, Steven, Craig, William W., Zoglauer, Andreas, Christensen, Finn E., Fryer, Chris L., Hailey, Charles J., Nynka, Melania, Markwardt, Craig, Zhang, William, & Stern, Daniel. BROADBAND X-RAY IMAGING AND SPECTROSCOPY OF THE CRAB NEBULA AND PULSAR WITH NuSTAR. United States. doi:10.1088/0004-637X/801/1/66.
Madsen, Kristin K., Harrison, Fiona, Grefenstette, Brian W., Reynolds, Stephen, An, Hongjun, Boggs, Steven, Craig, William W., Zoglauer, Andreas, Christensen, Finn E., Fryer, Chris L., Hailey, Charles J., Nynka, Melania, Markwardt, Craig, Zhang, William, and Stern, Daniel. Sun . "BROADBAND X-RAY IMAGING AND SPECTROSCOPY OF THE CRAB NEBULA AND PULSAR WITH NuSTAR". United States. doi:10.1088/0004-637X/801/1/66.
@article{osti_22522039,
title = {BROADBAND X-RAY IMAGING AND SPECTROSCOPY OF THE CRAB NEBULA AND PULSAR WITH NuSTAR},
author = {Madsen, Kristin K. and Harrison, Fiona and Grefenstette, Brian W. and Reynolds, Stephen and An, Hongjun and Boggs, Steven and Craig, William W. and Zoglauer, Andreas and Christensen, Finn E. and Fryer, Chris L. and Hailey, Charles J. and Nynka, Melania and Markwardt, Craig and Zhang, William and Stern, Daniel},
abstractNote = {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.},
doi = {10.1088/0004-637X/801/1/66},
journal = {Astrophysical Journal},
number = 1,
volume = 801,
place = {United States},
year = {Sun Mar 01 00:00:00 EST 2015},
month = {Sun Mar 01 00:00:00 EST 2015}
}