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
Galaxy groups and clusters are important systems for cosmology and galaxy evolution. The COSMOS survey has offered a unique data set to study the evolution of galaxy groups and clusters as well as their constituent galaxies.
In the latest contribution to this project, Dr. Gozaliasl and his collaborators provide a catalog of X-ray selected groups and clusters based on XMM and deep Chandra observations which offer an unprecedented spatial resolution in X-ray.
The brightest and most massive galaxies in the universe, the Brightest Cluster Galaxies (BCGs), tell a unique story of galaxy evolution. Today, BCGs are quiescent ellipticals hosted in relaxed galaxy clusters, with pasts fraught with mergers and high star formation rates (SFRs).
In a recent publication, Cooke et al. investigate how this active past may depend on local environment by estimating star formation in BCG progenitors in the COSMOS field out to a redshift of z ~ 3 (more than 11 billion years in the past).