Chandra Observations of the X-Ray Halo around the Crab Nebula
Abstract
Two Chandra observations have been used to search for thermal X-ray emission from within and around the Crab Nebula. Dead time was minimized by excluding the brightest part of the nebula from the field of view. A dust-scattered halo comprising 5% of the strength of the Crab is clearly detected, with surface brightness measured out to a radial distance of 18'. Coverage is 100% at 4', 50% at 12', and 25% at 18'. The observed halo is compared with predictions based on three different interstellar grain models, and one can be adjusted to fit the observation. This dust halo and mirror scattering form a high background region that has been searched for emission from shock-heated material in an outer shell. We find no evidence for such emission. We can set upper limits a factor of 10-1000 less than the surface brightness observed from outer shells around similar remnants. The upper limit for X-ray luminosity of an outer shell is ~1034 ergs s-1. Although it is possible to reconcile our observation with an 8-13 Msolar progenitor, we argue that this is unlikely.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2006
- DOI:
- 10.1086/498105
- arXiv:
- arXiv:astro-ph/0509636
- Bibcode:
- 2006ApJ...636..873S
- Keywords:
-
- ISM: Individual: Name: Crab Nebula;
- ISM: Supernova Remnants;
- X-Rays: ISM;
- Astrophysics
- E-Print:
- 26 pages, 12 figures, accepted by ApJ