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Astron. Astrophys. 325, 433-438

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Abundance and clustering of QSOs
in cosmic structure formation models

Hong-Guang Bi1 and Li-Zhi Fang2

1 Center for Astrophysical Sciences, Johns Hopkins University, Maryland, MD 21218, USA, and
Beijing Astronomical Observatory, Beijing 100080, China
2 Department of Physics, University of Arizona, Tucson, AZ 85721, USA

Received 13 January 1997 / Accepted 24 March 1997


When combining the observations of spatial abundance and two-point correlation function of QSOs, we can effectively set constraints on models of cosmic structure formation. Both the abundance of gravitationally confined halos and their two-point correlation functions can be calculated in the conventional Press-Schechter formalism. We apply this method to examine the properties of possible host halos of QSOs in three popular models: the standard cold dark matter (SCDM) model, the low density flat cold dark matter (LCDM) model and the cold-plus-hot dark matter (CHDM) model. The LCDM and CHDM models are normalized to the COBE-DMR observations, and the SCDM is normalized to FORMULA . We find that the SCDM and LCDM models can pass the abundance-plus-correlation test for QSOs. However, the CHDM are difficult to produce host halos to fit with the number density of high redshift QSOs and their clustering on large scales (10 h-1 Mpc) simultaneously. We studied various mechanisms, originated both gravitationally and non-gravitationally, which may lead to a biasing of the halo clustering. We conclude that these effects are too weak in order to release the trouble of the CHDM models.

Key words: quasar: general - cosmology: large-scale structure of universe - dark matter

Send offprint requests to: L.Z.Fang

© European Southern Observatory (ESO) 1997

Online publication: September 9, 1997
Last change: April 28, 1998