The AGN/starburst connection in luminous infrared galaxies

We are addressing the issue of whether there exists an evolutionary connect ion between starburst and AGN in luminous infrared galaxies. We are combini ng theoretical modelling with optical, radio and infrared data from IRAS fo r a large sample of 285 infrared galaxies with a range of luminosities. In this paper, we present a comparison between the optical spectroscopic data with the incidence of compact radio cores for a subsample of these galaxies . We find 90% of AGN type galaxies contain compact radio cores, while 37% o f starburst galaxies contain compact radio cores. The compact radio cores i n the starburst galaxies have a minimum brightness temperature of 3 x 10(5) K, higher than those of standard extended HII regions and may be obscured AGN or complexes of extremely luminous supernovae such as that seen in Arp 220.