2009/02/19 by Neal A. Miller, A. E. Hornschemeier, Ann E. Hornschemeier +6
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #astro-ph.CO
paper · pdf · doi:10.1088/0004-6256/137/5/4450
45 pages with 13 figures, accepted for publication in AJ
arxiv created 2009/02/19 · openalex publication_date 2009/04/07 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We investigate the radio luminosity function and radio source population for two fields within the Coma cluster of galaxies, with the fields centered on the cluster core and southwest infall region and each covering about half a square degree. Using VLA data with a typical rms sensitivity of 28 μJy per 4 4 beam, we identify 249 radio sources with optical counterparts brighter than r = 22. For cluster galaxies, these correspond to L 1.4 = 1.7 × 10 20 W Hz −1 (for a 5σ source) and M r = −13. Comprehensive optical spectroscopy identifies 38 of these as members of the Coma cluster, evenly split between sources powered by an active nucleus and sources powered by active star formation. The radio-detected star-forming galaxies are the dominant population only at radio luminosities between about 10 21 and 10 22 W Hz −1 , an interesting result given star formation dominates field radio luminosity functions for all luminosities lower than about 10 23 W Hz −1 . The majority of the radio-detected star-forming galaxies have characteristics of starbursts, including high specific star formation rates and optical spectra with strong emission lines. In conjunction with prior studies on post-starburst galaxies within the Coma cluster, this is consistent with a picture in which late-type galaxies entering Coma undergo a starburst prior to a rapid cessation of star formation. Optically bright elliptical galaxies ( M r ⩽ −20.5) make the largest contribution to the radio luminosity function at both the high (≳3 × 10 22 W Hz −1 ) and low (≲10 21 W Hz −1 ) ends. Through a stacking analysis of these optically bright ellipticals we find that they continue to harbor radio sources down to luminosities as faint as 3 × 10 19 W Hz −1 . However, contrary to published results for the Virgo cluster we find no evidence for the existence of a population of optically faint ( M r ≈ −14) dwarf ellipticals hosting strong radio AGNs.