Special Session SS23  1 July 2021

The main sequence of star-forming galaxies

Aims and scope

The tight correlation between star formation rate (SFR) and stellar mass of star-forming galaxies (the "main sequence''; MS) has been widely studied over the past decade. Previously, the MS was taken as evidence for the dominance of secular galaxy evolution. The MS is now a useful parameter space for identifying galaxy populations (such as starburst, transitional objects, and quiescent galaxies) and for studying variations in galaxy properties. This symposium is timely because we are still refining the measurement of the MS and its scatter across a range of stellar mass and redshift, which will be helped by upcoming surveys with Euclid and JWST. In addition, large cosmological hydrodynamical simulations are now realistic enough to allow for the mock observations and forward modeling of the simulated outcome that are needed to carry out consistent comparisons.

This symposium aims to bring together observers and simulators, working both at high and low redshifts. By bringing together theorists and observers, we can better understand and overcome the barriers to interpreting our results, and thereby better inform our interpretation of observed data and our modeling of galaxy evolution.


This special session will be split over three 1.5 hour blocks, each dedicated to one of the following topics, that will be introduced and discussed by an invited speaker (30min) and contributed talks (20min). We will also be accepting e-posters and presenters will have the opportunity to give a brief poster sparkler talk.

The three main topics covered in the session, and corresponding questions we intend to address are:

  • 1. Locus of the MS
  • How well do we really know the normalisation and slope of the MS at different redshifts? How should we compare studies, both observational and simulations, in a consistent way? What are the important systematics in stellar mass and SFR determinations?

  • 2. Global and spatially resolved MS
  • How do galaxies move within and along the MS? Where and when does star formation occur and quench inside galaxies? How do galaxy environment, morphology, AGN, and other mechanisms contribute to the scatter of the MS?

  • 3. Pushing the boundaries
  • Where will progress come from? What new techniques will allow us to accurately measure and simulate the MS over a wider mass and redshift range? What else can we learn from or using the MS?

Invited speakers

  • Katherine Whitaker (University of Massachusetts, USA)
  • Stijn Wuyts (University of Bath, UK)
  • Kartheik Iyer (University of Toronto, Canada)

Scientific organisers

Sarah Leslie (Chair, Leiden Observatory)
Mark Sargent (University of Sussex)
Annalisa Pillepich (Max Planck Institute for Astronomy, Heidelberg)
James Trayford (Institute of Cosmology & Gravitation, Portsmouth)
Elisabete da Cunha (ICRAR, University of Western Australia)


leslie @ strw.leidenuniv.nl

Updated on Mon Feb 15 14:37:13 CET 2021