Astronomy and Astrophysics – Astrophysics
Scientific paper
2002-11-21
Astronomy and Astrophysics
Astrophysics
Proceedings for the "X-ray Surveys: in the light of new observatories" workshop (Astron. Nachrichten, in press; includes an.cl
Scientific paper
Chandra is detecting a significant population of normal and starburst galaxies in extremely deep X-ray exposures. For example, approximately 15% of the sources arising in the 2 Ms Chandra Deep Field-North survey are fairly normal galaxies, where "normal" means "Milky Way-type" X-ray emission rather than simply exhibiting an "optically normal" spectrum. Many of these galaxies are being detected at large look-back times z=0.1-0.5, allowing the study of the evolution of X-ray binary populations over significant cosmological timescales. We are also detecting individual off-nuclear ultraluminous X-ray sources (e.g., X-ray binaries), providing the first direct constraints on the prevalence of lower-mass black holes at significantly earlier times. The X-ray emission from such "normal" galaxies may also be a useful star-formation rate indicator, based on radio/X-ray cross-identifications. We describe the contribution of normal galaxies to the populations which make up the X-ray background and present their directly measured X-ray number counts. We find that normal and starburst galaxies should dominate the 0.5--2 keV number counts at X-ray fluxes fainter than 7e-18 erg cm^{-2} s^{-1} (thus they will outnumber the "mighty" AGN). Finally, we look to the future, suggesting that it is important that the population of X-ray faint normal and starburst galaxies be well constrained in order to design the next generation of X-ray observatories.
Alexander Dave M.
Bauer Franz Erik
Brandt Wiliam N.
Garmire Gordon P.
Hornschemeier Ann Elizabeth
No associations
LandOfFree
The Weak Outnumbering the Mighty: Normal Galaxies in Deep Chandra Surveys does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Weak Outnumbering the Mighty: Normal Galaxies in Deep Chandra Surveys, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Weak Outnumbering the Mighty: Normal Galaxies in Deep Chandra Surveys will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-161868