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The Clustering of High-Redshift (2.9 $łeq$ z $łeq$ 5.1) Quasars in SDSS Stripe 82

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(2017)cite arxiv:1712.03128Comment: 21 Pages, 14 Figures.

Abstract

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.

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