COLA. III. Radio detection of active galactic nucleus in compact moderate luminosity infrared galaxies.
PARRA R., CONWAY J.E., AALTO S., APPLETON P.N., NORRIS R.P., PIHLSTROM Y.M. and KEWLEY L.J.
Abstract (from CDS):
We present results from 4.8 GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median LIR= 1011.01 L☉) COLA sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores (∼1021 W/Hz) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity.
galaxies: active - galaxies: starburst - infrared: galaxies - radio continuum: galaxies
VizieR on-line data:
<Available at CDS (J/ApJ/720/555): table1.dat table3.dat table4.dat>