Speaker
Brent Groves
(MPIA)
Description
In the local universe the mass of gas in galaxies is usually measured through the combination of the 21cm HI line, tracing the atomic gas, and the CO sub-millimeter lines that trace the molecular interstellar medium (ISM). However, the dust infrared continuum provides another tracer of the ISM mass, through two paths; the correlation of dust and gas mass, and the association of the total IR luminosity with CO luminosity (related to the Kennicutt-Schmidt relation). Here, using a matched sample of 36 galaxies from the KINGFISH (IR), HERACLES (CO), and THINGS (HI) surveys, we show the correlation of individual Herschel bands with the ISM mass. We find the tightest correlation of total gas mass with the longest wavelength data (SPIRE500), but that the molecular gas is more associated with the peak of the IR emission (e.g. PACS160). We provide fits to these relations for use with ongoing surveys with ALMA, and demonstrate how the equivalent widths of the CO lines provide an excellent tracer of the molecular gas fraction in galaxies.
Author
Brent Groves
(MPIA)