The XMM-Newton view of the Crab

¹ European Space Astronomy Centre (ESAC), ESA, Apartado – PO Box 50727, 28080 Madrid, Spain e-mail: mkirsch@sciops.esa.int
² Institut für Astronomie und Astrophysik der Universität Tübingen, Abteilung Astronomie, Sand 1, 72076 Tübingen, Germany
³ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
⁴ Department of Physics, University of Warwick, CV4 7AL, UK
⁵ Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Colaba, Mumbai-400005, India

Received: 28 December 2005
Accepted: 15 March 2006

Abstract

Aims.We discuss the current X-ray view of the Crab Nebula and Pulsar, summarising our analysis of observations of the source with the EPIC-pn camera on board the XMM-Newton observatory. Different modes of EPIC-pn were combined in order to yield a complete scenario of the spectral properties of the Crab resolved in space and time (pulse phase). In addition we give a description of the special EPIC-pn Burst mode and guidance for data reduction in that mode.

Methods.We analysed spectra for the nebula and pulsar separately in the 0.6-12.0 keV energy band. All data were processed with the SAS 6.0.0 XMM-Newton Scientific Analysis System package; models were fitted to the data with XSPEC 11. The high time resolution of EPIC-pn in its Burst mode (7 μs) was used for a phase resolved analysis of the pulsar spectrum, after determination of the period with epoch folding techniques. Data from the Small Window mode were processed and corrected for pile-up allowing for spectroscopy simultaneously resolved in space and time.

Results.The spatial variation of the spectrum over the entire region of the Crab shows a gradual spectral softening from the inner pulsar region to the outer nebula region with a variation in photon index, Γ, from 2.0 to 2.4. Pulse phase resolved spectroscopy of the Crab Pulsar reveals a phase dependent modulation of the photon index in form of a significant hardening of the spectrum in the inter-peak phase from during the pulse peak to .