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A.E. Kimball, Z. Ivezic (Univ. of Washington), P.J. Wiita, P. Barai (GSU)
Using continuum radio observations at 6 cm (GB6), 20 cm (FIRST and NVSS), and 92 cm (WENSS), we study the distribution of over 16,000 sources in the four-dimensional "color-magnitude-morphology-size" space. We find a clear structure, rather than a random scatter, and propose a simple, yet powerful, method for morphological classification of radio sources based on FIRST and NVSS measurements. For a subset of sources detected by all radio surveys, we obtain optical identifications using the SDSS data, and classify them as quasars and galaxies. Compact radio sources with flat radio spectra are dominated by quasars, while compact sources with steep spectra, and resolved radio sources, contain substantial numbers of both quasars and galaxies.
We gratefully acknowledge support by the NSF (AST-0507529).
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.