Zusammenfassung
We present a measurement of the two-point autocorrelation function of
photometrically-selected, high-$z$ quasars over $\sim$ 100 deg$^2$ on the Sloan
Digitial Sky Survey Stripe 82 field. Selection is performed using three machine
learning algorithms in a six-dimensional, optical/mid-infrared color space.
Optical data from the Sloan Digitial Sky Survey is combined with overlapping
deep mid-infrared data from the Spitzer IRAC Equatorial Survey and the
Spitzer-HETDEX Exploratory Large-area survey. Our selection algorithms
are trained on the colors of known high-$z$ quasars. The selected quasar sample
consists of 1378 objects, and contains both spectroscopically-confirmed quasars
and photometrically-selected quasar candidates. These objects span a redshift
range of $2.9 z 5.1$ and are generally fainter than $i=20.2$, a
regime which, until now, has lacked sufficient number density to perform
measurements of the autocorrelation function of photometrically-classified
quasars. We compute the angular correlation function of these data, fitting a
single power-law with an index of $= 1.45 0.279$ and amplitude of
$þeta_0 = 0.76 0.247$ arcmin. A dark matter model is fit to the angular
correlation function to estimate the linear bias. At the average redshift of
our survey ($z = 3.38$) the bias is $b = 7.32 0.12$. Using
this bias, we calculate a characteristic dark matter halo mass of
5.75--6.30$10^12h^-1 M_ødot$. We also estimate the bias for 1126
faint quasars in the survey ($i\geq20.2$) in the same manner and find similar
results to the full sample. These results imply that fainter quasars exhibit
similar clustering as brighter quasars at high-redshift. If confirmed, this
result suggests that quasar feedback is ineffective at blowing gas away from
the central region, and the central black hole rapidly grows at early times.
Nutzer