The observed tight correlation between the star formation rate (SFR) and stellar mass of star-forming galaxies (SFGs) is now well constrained over the last 10 Gyr. This so-called ?main sequence? (MS), whose normalization declines from z~3 to 0, is commonly interpreted as evidence that SFGs are mostly evolving through a steady and long mode of star-formation, likely sustained by the accretion of cold gas along the cosmic web. Over the last decade, a plethora of studies have investigated within this framework the physical properties of SFGs along and across the MS, establishing key scaling relations between, e.g., the stellar mass, gas content, and/or morphology of SFGs in the SFR-stellar mass plane. Interpreted in light of evermore realistic state-of-the-art hydrodynamical simulations, those relations have since been instrumental in tailoring galaxy evolution models. Despite these successes, the MS paradigm still fails to explain the more diverse than anticipated population of MS galaxies (e.g., starburst hidden within the MS), to describe precisely the march of SFGs across the SFR-stellar mass plane (e.g., smooth or stochastic SF history), and to explain crucial evolutionary phases of SFGs (e.g., their transition into quiescence). These limitations call for a more in-depth understanding of the evolutionary path of SFGs across the SFR-stellar mass plane and of the importance of secondary parameters (e.g., environment, morphology, AGNs, gas content) in shaping galaxies as we observe them today. In particular it is essential to go beyond the 1st order scaling relation and investigate how the complexity hidden within the main sequence can be used to unravel the physics involved in driving galaxy evolution over cosmic time. Such a census is yet to be obtained and potentially within reach thanks to evermore detailed observational constraints from current and upcoming surveys with, e.g., ALMA, JWST, and Euclid, and improved synergies with hydrodynamical simulations.

Building upon the successful 2021 Special Session 23 ''The Main Sequence of Star-Forming Galaxies'', this special session aims to focus more on the current and future challenges needed to be addressed within the MS framework rather than on its characteristics, universality and successes. Observers and simulators will be brought together to tackle questions raised by recent results.

Programme

1. A hidden diversity of galaxies in the universality of the main sequence
2. Beyond the snapshot, a dynamic approach to the main sequence: retracing the evolutionary paths of galaxies
3. Which galaxies depart from the main sequence and how?

Invited speakers

• Dr Annagrazia Puglisi Durham University
• Prof Avishai Dekel The Hebrew University
• Dr Katherine Wren Suess UC Santa Cruz
• Dr David Elbaz CEA/AIM

Scientific organisers

Laure Ciesla (LAM, Marseille, France)
Benjamin Magnelli (DAp-AIM, Saclay, France)
Georgios Magdis (DAWN, Denmark)
Paola Santini (INAF - Osservatorio Astronomico di Roma, Italy)
Sandro Tacchella (UNIST, Korea)
Vivienne Wild (University of Saint Andrews, UK)

Contact

laure.ciesla @ lam.fr
benjamin.magnelli @ cea.fr