Probing the Dark Matter-Galaxy Formation Connection with Lyman Alpha Emitting Galaxies

Eric Gawiser
Rutgers University


I will describe how our understanding of cosmological structure formation is used to probe the dark 
matter properties of high-redshift galaxies and to identify their present-day descendants. We studied 
the clustering properties and multiwavelength spectral energy distributions of a complete sample of 
162 Lyman Alpha Emitting (LAE) galaxies at z=3.1 discovered in deep narrow-band imaging of the 
MUSYC-ECDFS field. The LAEs exhibit a moderate clustering bias of b=1.7, which implies median  
dark matter halo masses of 1011 M_sun. The evolution of galaxy bias with redshift predicts that 
z=3.1 LAEs evolve into typical present-day galaxies with L~=L*, whereas other z>3 galaxy populations, 
including Lyman Break Galaxies and Active Galactic Nuclei, typically evolve into more massive galaxies.
A two-population fit to the LAE spectral energy distribution finds that the typical LAE has low 
stellar mass (109  M_sun), moderate star formation rate (2 M_sun/yr), a young component age of 
20 Myr, and little dust (A_V<0.2). This represents our first direct knowledge of the progenitors 
of spiral galaxies like the Milky Way seen when the universe was only 2 Gyr in age.      

References: Gawiser et al. 2007 (ApJ 671, 278), Francke et al. 2008  (ApJL 673, 13)