Title:

The Impact of Galactic Outflows on Galaxies and Intergalactic Gas



Romeel Davé
University of Arizona



Abstract:

Feedback from supernova-driven winds is an important driver of galaxy
properties at early epochs.  Quantifying such feedback is challenging
both observationally and theoretically.  I will present new cosmological
SPH simulations that self-consistently incorporate various models of
superwind feedback, and compare the resulting galaxy and IGM metal
absorber populations to observations at z~2-6.  Interestingly, our most
successful models have outflow speeds that scale with galaxy velocity,
such as in momentum-driven wind scenarios favored by observations of
local starbursts, while models with a single characteristic outflow
velocity fail key tests.  For instance, our successful models reproduce
the observed constancy of CIV absorption at those epochs seen in quasar
absorption line studies without invoking speculative early enrichment
from Pop >II stars, because energy input from winds counteracts the order
of magnitude increase in the overall IGM metallicity.  Our models also
reproduce the observed galaxy mass-metallicity relation, and give new
insights into its origin and evolution.  We preliminarily suggest that
outflows at all epochs may be fundamentally similar, which would be a
significant step towards understanding the impact of galactic outflows
on galaxies and the IGM across cosmic time.