Details

Autor(en) / Beteiligte

• Madsen, Kristin K.
• Reynolds, Stephen
• Harrison, Fiona
• An, Hongjun
• Boggs, Steven
• Christensen, Finn E.
• Craig, William W.
• Fryer, Chris L.
• Grefenstette, Brian W.
• Hailey, Charles J.
• Markwardt, Craig
• Nynka, Melania
• Stern, Daniel
• Zoglauer, Andreas
• Zhang, William

Titel

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

Ist Teil von

• The Astrophysical journal, 2015-03, Vol.801 (1), p.66

Ort / Verlag

United States

Erscheinungsjahr

2015

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• 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.