Fig. 4: Scaling of depletion times and gas masses.
From: The link between star formation and gas in nearby galaxies
a Average depletion times in the extended xGASS/xCOLD GASS sample of Mstar ~ 109−1011M⊙ nearby galaxies (solid lines with error bars) and in a mock sample with the same stellar mass distribution (dashed lines) showing good agreement. Blue/cyan lines (red/magenta lines) refer to molecular gas (to the sum of molecular and neutral gas including Helium). Galaxies with undetected or missing star formation rates (SFRs) are excluded from the analysis. Error bars correspond to standard errors of the bin averages. The solid green line shows the fit of the H2 depletion time from the PHIBSS survey10 covering z = 0–4 (dotted lines are extrapolations). b The scaling of the actual depletion times, i.e., if measured without observational errors and detection limits, for the galaxies in the mock sample. Galaxies with zero SFRs are excluded from the analysis. For typical offsets from the star-forming sequence, the molecular gas depletion time shows only a mild dependence (∝SFR−0.24) on SFR. c, d Same as a, b but showing the average change in gas masses relative to the peak position of the corresponding gas sequence with offset from the star-forming sequence. The peak position of the total gas sequence is given by the sum of the peak positions of the molecular and neutral gas sequences including Helium. Changes in star formation activity of typical starforming galaxies are tightly linked to changes in their molecular and total gas masses.
