The 2-10 keV luminosity as a Star Formation Rate indicator
Abstract
Radio and far infrared luminosities of star-forming galaxies follow a tight linear relation. Making use of ASCA and BeppoSAX observations of a well-defined sample of nearby star-forming galaxies, we argue that tight linear relations hold between the X-ray, radio and far infrared luminosities. The effect of intrinsic absorption is investigated taking NGC 3256 as a test case. It is suggested that the hard X-ray emission is directly related to the Star Formation Rate. Star formation processes may also account for most of the 2-10 keV emission from LLAGNs of lower X-ray luminosities (for the same FIR and radio luminosity). Deep Chandra observations of a sample of radio-selected star-forming galaxies in the Hubble Deep Field North show that the same relation holds also at high (0.2<~ z<~ 1.3) redshift. The X-ray/radio relations also allow a derivation of X-ray number counts up to very faint fluxes from the radio Log N-Log S a, which is consistent with current limits and models. Thus the contribution of star-forming galaxies to the X-ray background can be estimated.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 2003
- DOI:
- 10.1051/0004-6361:20021600
- arXiv:
- arXiv:astro-ph/0211304
- Bibcode:
- 2003A&A...399...39R
- Keywords:
-
- X-rays: galaxies;
- radio continuum: galaxies;
- galaxies: high-redshift;
- infrared: galaxies -;
- galaxies: fundamental parameters;
- galaxies: starburst;
- Astrophysics
- E-Print:
- Revised version: corrected typos in tables 1 and 2, one reference added. 13 pages, 7 figures. Astronomy &