Astrophys. J., 595, 685-697 (2003/October-1)
Hubble Space Telescope imaging in the Chandra Deep Field-South. III. Quantitative morphology of the 1 million second Chandra counterparts and comparison with the field population.
GROGIN N.A., KOEKEMOER A.M., SCHREIER E.J., BERGERON J., GIACCONI R., HASINGER G., KEWLEY L., NORMAN C., ROSATI P., TOZZI P. and ZIRM A.
Abstract (from CDS):
We present quantitative morphological analyses of 37 Hubble Space Telescope (HST)/WFPC2 counterparts of X-ray sources in the 1 Ms Chandra Deep Field-South (CDFS). We investigate (1) one-dimensional surface brightness profiles via isophotal ellipse fitting; (2) two-dimensional, point-spread function-convolved, bulge+disk+nucleus profile fitting; (3) asymmetry and concentration indices compared with all ∼3000 sources in our three WFPC2 fields; and (4) near-neighbor analyses comparing local environments of X-ray sources versus the field control sample. Significant nuclear point-source optical components appear in roughly half of the resolved HST/WFPC2 counterparts, showing a narrow range of FX/Fopt,nucconsistent with the several HST-unresolved X-ray sources (putative type 1 active galactic nuclei [AGNs]) in our fields. We infer that roughly half of the HST/WFPC2 counterparts host unobscured AGNs, comparable to analogous low-redshift AGN samples and suggesting no steep decline in the type 1/type 2 ratio out to the redshifts z∼0.5-1 typical of our sources. The concentration indices of the CDFS counterparts are clearly larger on average than those of the field distribution, at 5 σ, suggesting that the strong correlation between central black hole mass and host galaxy properties (including concentration index) observed in nearby galaxies is already evident by z∼0.5-1. By contrast, the asymmetry index distribution of the 21 resolved CDFS sources at I<23 is indistinguishable from that of the I<23 field. Moreover, the frequency of I<23 near neighbors around the CDFS counterparts is not significantly different from that of the field sample. These results, combined with previous similar findings for local samples, suggest that recent merger/interaction history is not a good indicator of AGN activity over a substantial range of look-back time.
Galaxies: Active - Galaxies: Fundamental Parameters - Galaxies: Structure - Surveys - X-Rays: Galaxies
VizieR on-line data:
<Available at CDS (J/ApJ/595/685): table1.dat table2.dat>
Table 1: [GKS2003] DD.dddddd+DD.dddddd N=3030.
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