THE DARK SIDE OF QSO FORMATION AT HIGH REDSHIFTS
- Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States)
- Department of Astrophysical and Planetary Sciences, CASA University of Colorado, Boulder, CO 80309 (United States)
- Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)
Observed high-redshift QSOs, at z {approx} 6, may reside in massive dark matter (DM) halos of more than 10{sup 12} M{sub sun} and are thus expected to be surrounded by overdense regions. In a series of 10 constrained simulations, we have tested the environment of such QSOs. The usage of constrained realizations has enabled us to address the issue of cosmic variance and to study the statistical properties of the QSO host halos. Comparing the computed overdensities with respect to the unconstrained simulations of regions empty of QSOs, assuming there is no bias between the DM and baryon distributions, and invoking an observationally constrained duty cycle for Lyman break galaxies, we have obtained the galaxy count number for the QSO environment. We find that a clear discrepancy exists between the computed and observed galaxy counts in the Kim et al. samples. Our simulations predict that on average eight z {approx} 6 galaxies per QSO field should have been observed, while Kim et al. detect on average four galaxies per QSO field compared to an average of three galaxies in a control sample (GOODS fields). While we cannot rule out a small number of statistics for the observed fields to high confidence, the discrepancy suggests that galaxy formation in the QSO neighborhood proceeds differently than in the field. We also find that QSO halos are the most massive of the simulated volume at z {approx} 6 but this is no longer true at z {approx} 3. This implies that QSO halos, even in a case where they are the most massive ones at high redshifts, do not evolve into the most massive galaxy clusters at z = 0.
- OSTI ID:
- 21578309
- Journal Information:
- Astrophysical Journal, Vol. 736, Issue 1; Other Information: DOI: 10.1088/0004-637X/736/1/66; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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