Homogeneity of bright radio sources at 15 GHz on the sky and in the space

Arshakian, T. G.; Ros, E.; Zensus, J. A.; Lister, M. L.

Homogeneity of bright radio sources at 15 GHz on the sky and in the space

Authors

Description

A revised sample of the 2 cm Very Long Baseline Array (VLBA) survey is studied to test the isotropic distribution of radio sources on the sky and their uniform distribution in space. The revised sample is complete to flux-density limits of 1.5 Jy for positive declinations and 2 Jy for declinations between 0 and -20 degrees. At present the active galactic nuclei sample comprises 122 members. Application of the two-dimensional Kolmogorov-Smirnov (K-S) test shows that there is no significant deviation from the homogenous distribution in the sky, while the V/Vmax test shows that the space distribution of active nuclei is not uniform at high confidence level (99.9%). This is indicative of a strong luminosity and/or density evolution implying that active nuclei (or jet activity phenomena) were more populous at high redshifts, z~2.
5 pages, 2 figures. To be published in "Radio astronomy at 70: from Karl Jansky to microjansky", JENAM-2003 Symposium, eds. L.Gurvits and S.Frey (Baltic Astronomy). The paper in gzipped postscript format available at ftp://ftp.mpifr-bonn.mpg.de/outgoing/tigar/papers/JENAM-2003.ps.gz