The Molecular Kennicutt-Schmidt Law in Arp 240 on Sub-kpc Scales

Star formation has long been known to be associated with molecular gas, with higher (surface) densities of molecular gas generally correlating with higher (surface) densities of star formation. Galaxy interactions and mergers are known to have globally enhanced star formation but it has been a matter of debate if star formation and molecular gas are correlated in the same way as in galaxies with normal star formation rates. In “The Arp 240 Galaxy Merger: A Detailed Look at the Molecular Kennicutt-Schmidt Star Formation Law on Sub-kpc Scales” (Saravia+) we used NRAO Very Large Array (VLA) observations and Atacama Large Millimeter Array (ALMA) observations to study the star formation in an early stage galaxy interaction. The VLA S-band (3 GHz) measurements probe the star formation and ALMA CO (2–1) observations trace the molecular gas. We find that the brighter regions show a steeper, linear relation between the amount of molecular gas and the star formation rate, while the fainter regions show a sub-linear relation. The star formation rate (surface) density is correlated with the turbulent energy in the gas, possibly tracing the impact of energy injection from star formation into the gas.

The paper has been accepted for publication in the Astrophysical Journal and a preprint is available at the link above.