X-ray observations of the edge-on star-forming galaxy NGC 891 and its supernova SN1986J
Abstract
We present XMM-Newton observations of NGC 891, a nearby edge-on spiral galaxy. We analyse the extent of the diffuse emission emitted from the disc of the galaxy, and find that it has a single-temperature profile with best-fitting temperature of 0.26 keV, though the fit of a dual-temperature plasma with temperatures of 0.08 and 0.30 keV is also acceptable. There is a considerable amount of diffuse X-ray emission protruding from the disc in the north-west direction out to approximately 6 kpc. We analyse the point-source population using a Chandra observation, using a maximum-likelihood method to find that the slope of the cumulative luminosity function of point sources in the galaxy is -0.77+0.13-0.1. Using a sample of other local galaxies, we compare the X-ray and infrared properties of NGC 891 with those of `normal' and starburst spiral galaxies, and conclude that NGC 891 is most likely a starburst galaxy in a quiescent state. We establish that the diffuse X-ray luminosity of spirals scales with the far-infrared luminosity as LX~L0.87+/-0.07FIR, except for extreme starbursts, and NGC 891 does not fall in the latter category. We study the supernova SN1986J in both XMM-Newton and Chandra observations, and find that the X-ray luminosity has been declining with time more steeply than expected (LX~t-3).
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- September 2005
- DOI:
- 10.1111/j.1365-2966.2005.09336.x
- arXiv:
- arXiv:astro-ph/0506657
- Bibcode:
- 2005MNRAS.362..581T
- Keywords:
-
- supernovae: individual: SN1986J;
- galaxies: individual: NGC 891;
- galaxies: starburst;
- X-rays: diffuse background;
- X-rays: galaxies;
- Astrophysics
- E-Print:
- 12 pages, 11 figures, accepted for publication in MNRAS