Binary Quasars in the Sloan Digital Sky Survey: Evidence for Excess Clustering on Small Scales
Abstract
We present a sample of 221 new quasar pairs with proper transverse separations Rprop<1 h-1 Mpc over the redshift range 0.5<z<3.0, discovered from an extensive follow-up campaign to find companions around the Sloan Digital Sky Survey and 2dF QSO Redshift Survey quasars. This sample includes 26 new binary quasars with separations Rprop<50 h-1 kpc (θ<10''), more than doubling the number of such systems known. We define a statistical sample of binaries selected with homogeneous criteria and compute its selection function, taking into account sources of incompleteness. The first measurement of the quasar correlation function on scales 10 h-1 kpc<Rprop<400 h-1 kpc is presented. For Rprop<~40 h-1 kpc, we detect an order of magnitude excess clustering over the expectation from the large-scale (Rprop>~3 h-1 Mpc) quasar correlation function, extrapolated down as a power law (γ=1.53) to the separations probed by our binaries. The excess grows to ~30 at Rprop~10 h-1 kpc and provides compelling evidence that the quasar autocorrelation function gets progressively steeper on submegaparsec scales. This small-scale excess can likely be attributed to dissipative interaction events that trigger quasar activity in rich environments. Recent small-scale measurements of galaxy clustering and quasar-galaxy clustering are reviewed and discussed in relation to our measurement of small-scale quasar clustering.
- Publication:
-
The Astronomical Journal
- Pub Date:
- January 2006
- DOI:
- 10.1086/498235
- arXiv:
- arXiv:astro-ph/0504535
- Bibcode:
- 2006AJ....131....1H
- Keywords:
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- Cosmology: Observations;
- Cosmology: Large-Scale Structure of Universe;
- Galaxies: Quasars: General;
- Surveys;
- Astrophysics
- E-Print:
- 25 pages, 12 figures, 9 tables. Submitted to the Astronomical Journal