The High-Energy emission of the Crab Nebula with Integral SPI
The spectral shape of the Crab nebula emission between 20 keV and 5 MeV brings
new important information in a spectral region where the data are rather scarce.
The 3 spectra presented here correspond to SPI observations of the Crab Nebula
during three periods between February 2003 and September 2008.
While the emission in the X-ray domain and above the MeV region follows simple
power laws (photon index of 2.06 and 2.23 respectively), the SPI data show, that
the hard X-ray regime can be seen as a transition region with a smooth curvature
around 100 keV. In addition this work point out the remarkable constancy of the
Crab nebula spectrum.
These data have been obtained thanks to regular Crab observations by INTEGRAL. The
analysis of these observations demonstrates the stability of the SPI instrument
over 6 years.
Finally, thanks to an extensive pre-launch calibration work and to the instrument
behaviour, the obtained spectrum can be considered as absolute as it only relies
on the ground calibration work.
Related links:
The High Energy Emission of the Crab Nebula from 20 keV to 6 MeV with INTEGRAL,
Jourdain, E. and Roques, J.P., 2009, ApJ, 704
http://arxiv.org/abs/0909.3437
