Galaxy Evolution and Star Formation Efficiency in the Last Half of the Universe

TL;DR

This study investigates galaxy evolution and star formation efficiency at intermediate redshifts using CO emission surveys, revealing extended emission and increased FIR-to-CO luminosity ratios indicative of evolving starburst activity.

Contribution

It provides new observational data on CO emission in galaxies at z ~ 0.2-0.6, bridging the gap between local and high-redshift galaxy studies.

Findings

50% detection rate of CO emission in surveyed galaxies

Extended emission suggests large-scale molecular gas reservoirs

Enhanced FIR-to-CO luminosity ratio indicates increased starburst activity

Abstract

We present the results of a CO(1-0) emission survey with the IRAM 30m of 30 galaxies at moderate redshift (z ~ 0.2-0.6) to explore galaxy evolution and in particular the star formation efficiency, in the redshift range filling the gap between local and very high-z objects. Our detection rate is about 50%. One of the bright objects was mapped at high resolution with the IRAM interferometer, and about 50% of the total emission found in the 27 arcsec (97 kpc) single dish beam is recovered by the interferometer, suggesting the presence of extended emission. The FIR-to-CO luminosity ratio is enhanced, following the increasing trend observed between local and high-z ultra-luminous starbursts.