Nick Battaglia

Reionization on Large Scales: A New Parametric Model and CMB Observables

The epoch of reionization (EoR) marks the emergence of the first luminous sources: stars, galaxies, and quasars. These luminous sources convert the cold and neutral intergalactic medium into a warm and highly ionized one. We present a new method for modeling inhomogeneous reionization on large scales. Utilizing large-scale high-resolution radiative transfer hydrodynamic simulations of cosmological reionization we show that the density and redshift of reionizaton fields are highly correlated on large scales ( > 1Mpc/h) and can be easily modeled by a linear bias. Therefore, we are able to quickly construct a redshift of reionization field from any large-scale density field by simply filtering this density field. We present Cosmic Microwave Background observables from this model and illustrate the potential to constrain the mid-point and duration of EoR when combining these predictions with future observations.

Kim Venn
(University of Victoria)

Title: Inhomogeneous Mixing in Dwarf Galaxies

Spectroscopy of stars in nearby galaxies has become routine in the past decade with the 8-10 meter class telescopes and high efficiency spectrographs. Large datasets of medium resolution spectroscopy have provided detailed studies of the metallicity and dynamical distributions of the stars in the Local Group dwarf galaxies. Follow up high resolution spectroscopy has been used to track the origins and chemical evolution of these systems. Inhomogeneous mixing appears to be indicated in the low mass classical dwarfs, but may be indicated throughout these systems, including at early times where these conditions would affect our understanding of the proto-galactic fragments that dominate hierarchical merging theories.