Lambda = 3 mm line survey of nearby active galaxies

TL;DR

This study conducted a 3mm line survey of nearby active galaxies using IRAM 30m, identifying molecular signatures and comparing chemical compositions to distinguish starburst, AGN, and ULIRG characteristics.

Contribution

First comprehensive molecular line survey at 3mm of multiple nearby active galaxies, revealing new molecular detections and chemical differences among galaxy types.

Findings

Detected new molecules in M82 and NGC253.

Identified molecules characteristic of starbursts, AGNs, and ULIRGs.

Compared molecular abundances to characterize galaxy chemistry.

Abstract

We used the IRAM 30m telescope to observe the frequency range [86-116]GHz towards the central regions of the starburst galaxies M83, M82, and NGC253, the AGNs M51, NGC1068, and NGC7469, and the ULIRGs Arp220 and Mrk231. Assuming LTE conditions, we calculated the column densities of 27 molecules and 10 isotopologues. Among others, we report the first tentative detections of CH3CHO, HNCO, and NS in M82 and, for the first time in the extragalactic medium, HC5N in NGC253. Halpha recombination lines were only found in M82 and NGC253. Vibrationally excited lines of HC3N were only detected in Arp220. CH3CCH emission is only seen in the starburst-dominated galaxies. By comparison of the fractional abundances among the galaxies, we looked for the molecules that are best suited to characterise the chemistry of starbursts, AGNs and ULIRGs, as well as the differences among galaxies within the same group.