How warm is the molecular gas in active environments?

TL;DR

This paper investigates the temperature of molecular gas in active galactic environments using formaldehyde line diagnostics, aiming to understand its impact on star formation and the initial mass function.

Contribution

It demonstrates the effectiveness of formaldehyde lines as tracers for molecular gas temperature in starburst and AGN environments, providing new observational insights.

Findings

Molecular gas in active environments can reach temperatures around 100 K.

Formaledehyde lines are effective diagnostics for gas temperature in external galaxies.

Results suggest warmer molecular gas in starburst and AGN regions.

Abstract

The question whether or not the initial mass function is universal, i.e. the same in all kinds of environments, is of critical importance for the theory of star formation and still intensely debated. A top-heavy initial mass function may be the result of star formation out of dense molecular clouds with a temperature of ~ 100 K. Such a molecular gas phase is not commonly found in the Galactic plane, but may be present in active environments like cores of starburst galaxies or AGN. Unfortunately, the kinetic temperature of the molecular gas in external galaxies is often not well constrained. Having proven the diagnostic power of selected formaldehyde lines as tracers of the properties of the molecular gas in external galaxies, we have engaged in observing these diagnostic lines in a number of starburst galaxies or near AGN. This contribution presents the latest results of these studies.