SCIENCE BLOG - Paper: ALMA reveals a compact and massive molecular outflow driven by the young AGN in a nearby ULIRG

Luke Holden - 2nd April 2024

I'm very happy to announce that the 3rd first-author paper of my PhD has been accepted for publication in MNRAS, and is now available on arXiv and MNRAS advanced access.

Here, we use high-spatial-resolution (0.11 arcsecond beam) ALMA CO(1-0) observations to reveal and characterise a compact, massive cold molecular outflow in the primary nucleus of ULIRG F13451+1231 (also known as 4C 12.50). This object has had nuclear outflows previously confirmed in coronal, warm ionised, and neutral atomic gas phases, however, there had not been an existing robust detection of molecular outflows.

The cold molecular mass outflow rate that we find is ~230 solar masses per year - orders of magnitude higher than those of the other outflow phases - and the kinetic power is ~1.4% the bolometric luminosity of the AGN (three times the combined kinetic power of the other phases). Therefore, this detection of a cold molecular outflow component significantly increases the known mass and power of the total outflow in this important object, demonstrating the importance of multi-wavelength observations that trace multiple gas phases.

Crucially, in showing that the outflow is compact (r<120pc), this study provides evidence that powerful radio sources can accelerate compact outflows, and highlights that high-spatial-resolution observations are needed to properly characterise and quantify their properties.