Speaker
Description
The Circumgalactic Medium (CGM) plays a vital role in galaxy evolution, yet its connection to cool gas remains poorly understood. We show that post-starburst galaxies, which recently underwent rapid star formation quenching, exhibit distinct CGM properties. Using ~850,000 quasar sightlines from the SDSS CMASS sample, we measure the stacked MgII equivalent width as a function of impact parameter for massive galaxies (>$10^{11} M_⊙$).
Consistent with previous results, we find that MgII absorption decreases with distance, indicating a decline in cool gas abundance. At ~1 Mpc, MgII levels converge across galaxy types, marking a transition from the CGM to the intergalactic medium. Post-starburst galaxies show significantly enhanced MgII absorption compared to star-forming and non-star-forming galaxies. This unique CGM signature in post-starburst galaxies potentially links to outflows observed in their interstellar medium, or alternatively to the impact on their CGM of a significant recent disruption, such as caused by galaxy mergers.
