Lyman Alpha Emitting Galaxies at z~3:  Progenitors of Present-day L* Galaxies

Eric Gawiser (Rutgers University)

We studied the spatial clustering of 160 Lyman Alpha Emitting (LAE)
galaxies at z=3.1 in the MUSYC-ECDFS field.  We used cosmological
structure formation theory to infer the dark matter halo masses of
this population and to identify their present-day descendants.  The
LAEs exhibit a moderate clustering bias of b=1.7, which implies median
dark matter halo masses of 10^11 M_sun.  The evolution of galaxy bias
with redshift predicts that z=3.1 LAEs evolve into typical present-day
galaxies with L~=L*.  Other z>3 galaxy populations, including Lyman
Break Galaxies and Active Galactic Nuclei, typically evolve into more
strongly clustered present-day galaxies such as massive ellipticals
and cluster members.  Analysis of the LAE spectral energy distribution
finds that the typical LAE has low stellar mass (10^9 M_sun), moderate
star formation rate (2 M_sun/yr), a starburst 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 old.  References: Gawiser et al. 2007 (ApJ
671, 278), Francke et al. 2008 (ApJL 673, 13)