Extranuclear star forming regions in LIRGs are (mostly) normal

13 June 2019

Luminous and Ultraluminous Infrared Galaxies (U/LIRGs) are known to have extreme star formation properties, both in their nuclei and on average. Only recently have the observing capabilities become available to probe the star formation in these systems in a resolved fashion, to see how the star formation changes across the system, and to deep sensitivities, to explore fainter emission. In “A Very Large Array Survey of Luminous Extranuclear Star-forming Regions in Luminous Infrared Galaxies in GOALS” (Linden+) we examined the properties of star forming regions outside the nuclei of a sample of U/LIRGs using new radio observations. Though the star formation characteristics of the nuclei are known to differ from normal galaxies, in this paper we show that the extranuclear regions are similar to the properties of “normal” star forming regions in non-U/LIRGs. In particular, their fraction of the 33 GHz emission is similar to that of normal galaxies (in contrast to the nuclei which have evidence of suppressed thermal fractions). They also have similar fractional rates of local stellar mass growth (i.e., the sub-galactic star forming main sequence). The article has been accepted for publication in the Astrophysical Journal and has been posted to arXiv (link above).