Unveiling Environmental Quenching in Galaxies at High Redshift Fahmi Aziz Firmansyah (a*), Dicky Setiawan (a), Widya Syafna Azhalia (a)
a) Department of Astronomy, Institut Teknologi Bandung
Jalan Ganesha 10, Bandung 40132, Indonesia
fahmiazizfirmansyah[at]gmail.com
Abstract
This project addresses a central question in galaxy evolution: how environment affects star formation activity and quenching, and how this evolves over cosmic time. We are investigating this question to understand the relative importance of internal processes and external environmental factors in shaping galaxy properties.
We will explore these questions by analyzing the specific star formation rate (sSFR) and quiescent fraction of galaxies as a function of group richness. Our research will utilize the newly released COSMOS-Web deep galaxy group catalog (Toni et al. 2025), which, based on JWST COSMOS-Web imaging, includes over 1600 galaxy groups extending out to \(z\approx3.7\). The analysis will involve measuring sSFRs and identifying quiescent galaxies across a range of group environments, using both group richness \(\lambda_*\) and amplitude (A) as mass proxies.
We expect to determine when and how environmental quenching becomes effective by comparing results across redshift bins. We will then compare these trends to the continuous-density results from Taamoli et al. (2024), who studied how sSFR and star formation rate density vary with local overdensity across \(0.4<z<4.\)
This comparison will test whether discrete group environments capture the same evolutionary trends observed in continuous density fields-including the potential reversal of the SFR-density relation at \(z>2\). The findings will help clarify whether group-scale environment is a key driver of quenching across cosmic time, providing crucial insights into galaxy evolution in the early universe.
Keywords: Galaxy evolution- Star formation quenching- SFR-density relation
