Radio Continuum and Star Formation in CO-rich Early Type Galaxies

TL;DR

This study uses high-resolution radio observations to confirm star formation activity in CO-rich early-type galaxies, showing that such galaxies can have significant star formation without active galactic nuclei.

Contribution

It provides new high-resolution radio data linking star formation to CO-rich early-type galaxies and demonstrates the prevalence of star formation in these galaxies.

Findings

Radio continuum correlates with star formation in most studied galaxies.

Average star formation rate is about 2 solar masses per year.

No evidence of active galactic nuclei in the sample.

Abstract

In this paper we present new high resolution VLA 1.4 GHz radio continuum observations of five FIR bright CO-rich early-type galaxies and two dwarf early-type galaxies. The position on the radio-FIR correlation combined with striking agreements in morphology between high resolution CO and radio maps show that the radio continuum is associated with star formation in at least four of the eight galaxies. The average star formation rate for the sample galaxies detected in radio is approximately 2 solar masses per year. There is no evidence of a luminous AGN in any of our sample galaxies. We estimate Toomre Q values and find that the gas disks may well be gravitationally unstable, consistent with the above evidence for star formation activity. The radio continuum emission thus corroborates other recent suggestions that star formation in early type galaxies may not be uncommon.