Did most high-redshift quasars escape detection?
C. Wolf 1,
K. Meisenheimer 1,
H.-J. Röser 1,
S.V.W. Beckwith 1,3,
R. Fockenbrock 1,
H. Hippelein 1,
B. von Kuhlmann 1,
S. Phleps 1 and
E. Thommes 2
Received 4 November 1998 / Accepted 15 December 1998
We present follow-up spectroscopy to the Calar Alto Deep Imaging Survey (CADIS), reporting on the quasars in the CADIS 16 h-field, and including preliminary data from two other fields. In this field we found six quasars at redshift which are brighter than , while surface densities determined in previous surveys are reported to be below one on average. This is the highest reported surface density of high-redshift quasars within the given limits. We believe this result to be a consequence of the multicolor database and the search technique used in CADIS.
Our observations further seem to indicate that the density of high-redshift quasars is also higher than predicted by the luminosity function of Warren et al. (1994) by a factor of three, implying that common search methods have overlooked the majority of high-redshift quasars at this magnitude level. In particular, an application of the test to our preliminary list of AGNs with and yields , characterizing our preliminary redshift distribution as flat.
Key words: methods: data analysis techniques: photometric surveys galaxies: quasars: general cosmology: observations
© European Southern Observatory (ESO) 1999
Online publication: March 1, 1999