Lunch talk on May. 26, 2025

Circumgalactic Enrichment by a Multi-Galaxy Merger at Redshift 6.7

Speaker: Weida Hu (Texas A&M University)

Venue: Video Conference

Time: 12:45 PM, Monday, May. 26, 2025

Abstract: 

Recent JWST observations have unveiled an unexpectedly large number of massive galaxies in the early universe. Many of these massive galaxies have already been quiescent for several hundred million years, challenging the standard galaxy formation theories. In this talk, I will present a spectacular merger of at least five galaxies (JQ) at redshift 6.7 identified with JWST. JQ's high mass and star formation rate are consistent with the star formation history of those unexpected massive quiescent galaxies, offering a plausible evolutionary pathway for the formation of such galaxies. We also detect a large [OIII]+Hbeta emitting gaseous halo surrounding and connecting four galaxies in the JQ, suggesting the existence of heavy elements in the surrounding CGM. This provides direct evidence for the metal enrichment of galaxies' environments through merger-induced tidal stripping, just 800 Myr after the Big Bang.

Report PPT:  SWIFAR_Weida Hu.pdf