14 research outputs found
AEGIS: The Clustering of X-ray AGN Relative to Galaxies at z~1
We measure the clustering of non-quasar X-ray AGN at z=0.7-1.4 in the AEGIS
field. Using the cross-correlation of 113 Chandra-selected AGN, with a median
log L_X=42.8 erg s^-1, with ~5,000 DEEP2 galaxies, we find that the X-ray AGN
are fit by a power law with a clustering scale length of r_0=5.95 +/-0.90 h^-1
Mpc and slope gamma=1.66 +/-0.22. X-ray AGN have a similar clustering amplitude
as red, quiescent and `green' transition galaxies at z~1 and are significantly
more clustered than blue, star-forming galaxies. The X-ray AGN clustering
strength is primarily determined by the host galaxy color; AGN in red host
galaxies are significantly more clustered than AGN in blue host galaxies, with
a relative bias that is similar to that of red to blue DEEP2 galaxies. We
detect no dependence of clustering on optical brightness, X-ray luminosity, or
hardness ratio within the ranges probed here. We find evidence for galaxies
hosting X-ray AGN to be more clustered than a sample of galaxies with matching
joint optical color and magnitude distributions. This implies that galaxies
hosting X-ray AGN are more likely to reside in groups and more massive dark
matter halos than galaxies of the same color and luminosity without an X-ray
AGN. In comparison to optically-selected quasars in the DEEP2 fields, we find
that X-ray AGN at z~1 are more clustered than optically-selected quasars (with
a 2.6-sigma significance) and therefore likely reside in more massive dark
matter halos. Our results are consistent with galaxies undergoing a quasar
phase while in the blue cloud before settling on the red sequence with a
lower-luminosity X-ray AGN, if they are similar objects at different
evolutionary stages.Comment: 18 pages, accepted to ApJ, minor changes made to match accepted
version, Figure 1 adde
The First Data Release of the Sloan Digital Sky Survey
The Sloan Digital Sky Survey has validated and made publicly available its
First Data Release. This consists of 2099 square degrees of five-band (u, g, r,
i, z) imaging data, 186,240 spectra of galaxies, quasars, stars and calibrating
blank sky patches selected over 1360 square degrees of this area, and tables of
measured parameters from these data. The imaging data go to a depth of r ~ 22.6
and are photometrically and astrometrically calibrated to 2% rms and 100
milli-arcsec rms per coordinate, respectively. The spectra cover the range
3800--9200 A, with a resolution of 1800--2100. Further characteristics of the
data are described, as are the data products themselves.Comment: Submitted to The Astronomical Journal. 16 pages. For associated
documentation, see http://www.sdss.org/dr