Relating mass and star formation rates

September 27, 2020

What's the relation between the mass of galaxies and their rate for star formation? The new paper by Sarah Leslie and collaborators measures this relation for 200,000 galaxies in the COSMOS field.

This relation between rate of star formation (SFR) and mass is called the main-sequence. It is observed across a large amount of cosmic time (redshifts). The paper by Leslie et al. provides a coherent measurement of this main-sequence up to redshift of 5 (about 13 billion years in the past). To do this, they use mean stacks of 3 GHz radio-continuum images to derive average SFRs for ∼ 200,000 mass-selected galaxies.

Check out her YouTube video explaining her paper: https://www.youtube.com/watch?v=tMNp4qXp0FM

And here are some of the imporant science results:

  • The flattening of the main-sequence at higher stellar masses becomes more prominent at later cosmic times
  • The flattening is likely caused by so called bulge-dominated galaxies (these might be galaxies that are about to stop their star formation)
  • There is a characteristic mass that contributes the most to the overal volume density of SFR. This mass increases with redshift up to z = 2.5
  • No significant variation of the main-sequence relation is found for galaxies in different environments (meaning galaxies living in groups or isolated)
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Interested? Check out the paper: https://ui.adsabs.harvard.edu/…/2020ApJ...899...58L/abstract