Prevalence of X-ray variability in the Chandra Deep Field South

Details Prevalence of X-ray variability in the Chandra Deep Field South Prevalence of X-ray variability in the Chandra Deep Field South

2004-04-21

arxiv.org/abs/astro-ph/0404418v1

Astrophys.J. 611 (2004) 93-106

Astronomy and Astrophysics

Astrophysics

24 pages, including 15 figures and 1 table. In press on ApJ

Scientific paper

10.1086/421967

We studied the X-ray variability of sources detected in the Chandra Deep Field South (Giacconi et al. 2002), nearly all of which are low to moderate z AGN (Tozzi et al. 2001). We find that 45% of the sources with >100 counts exhibit significant variability on timescales ranging from a day up to a year. The fraction of sources found to be variable increases with observed flux, suggesting that >90% of all AGNs possess intrinsic variability. We also find that the fraction of variable sources appears to decrease with increasing intrinsic absorption; a lack of variability in hard, absorbed AGNs could be due to an increased contribution of reflected X-rays to the total flux. We do not detect significant spectral variability in the majority (~70%) of our sources. In half of the remaining 30%, the hardness ratio is anti-correlated with flux, mimicking the high/soft-low/hard states of galactic sources. The X-ray variability appears anti-correlated with the luminosity of the sources, in agreement with previous studies. High redshift sources, however, have larger variability amplitudes than expected from extrapolations of their low-z counterparts, suggesting a possible evolution in the accretion rate and/or size of the X-ray emitting region. Finally, we discuss some effects that may produce the observed decrease in the fraction of variable sources from z=0.5 out to z=2.

Affiliated with

Also associated with

No associations

Rating

Prevalence of X-ray variability in the Chandra Deep Field South 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 Prevalence of X-ray variability in the Chandra Deep Field South, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Prevalence of X-ray variability in the Chandra Deep Field South will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-17947