Mapping the Gas Cycle around Galaxies with IFU Spectroscopy and Gravitational Lensing
Speaker: Dr. Ahmed Shaban
Affiliation: University of South Carolina
Date: October 14, 2026
Abstract:
Gas accretion, removal, and recycling regulate star formation and galaxy evolution.
In this talk, I will present studies of neutral gas reservoirs, galactic outflows,
and the circumgalactic medium (CGM) at cosmic noon (z~1-3), when the Universe formed
stars at its highest rate. In this talk, I will show how integral field spectroscopy
from Keck/KCWI and VLT/MUSE, combined with nature’s own telescope, strong gravitational
lenses, lets us map this gas in unprecedented Detail.
First, I will discuss Lyα emission from galaxies associated with damped Lyα absorbers
(DLAs), which trace the dominant reservoirs of neutral hydrogen in the early universe.
By removing the glare of bright background quasars, we uncover the faint galaxies
associated with DLAs at redshifts of z~2-3, and examine connections between Lyα luminosity,
impact parameter, HI column density, and metallicity, linking the galaxies directly
to their neutral gas reservoirs.
Second, I will show how gravitationally lensed background sources spatially resolve
small scales of CGM, and reveal galactic outflows extending tens of kiloparsecs and
let us perform “tomography” of foreground gas halos of galaxies and galaxy clusters.
Together, these studies trace the distribution and cycling of gas from galaxies to
their large-scale environments.