PROBING THE PHYSICAL PROPERTIES OF z = 4.5 Ly α EMITTERS WITH SPITZER

We present the results from a stellar population modeling analysis of a sample of 162 z = 4.5 and 14 z = 5.7 Ly alpha emitting galaxies (LAEs) in the Bootes field, using deep Spitzer/IRAC data at 3.6 and 4.5 mu m from the Spitzer Ly alpha Survey, along with Hubble Space Telescope NICMOS and WFC3 imaging at 1.1 and 1.6 mu m for a subset of the LAEs. This represents one of the largest samples of high-redshift LAEs imaged with Spitzer IRAC. We find that 30/162 (19%) of the z = 4.5 LAEs and 9/14 (64%) of the z = 5.7 LAEs are detected at > or =3 alpha in at least one IRAC band. Individual z = 4.5 IRAC-detected LAEs have a large range of stellar mass, from 5 x 10 super(8)-10 super(11) M sub([middot in circle]). One-third of the IRAC-detected LAEs have older stellar population ages of 100 Myr-1 Gyr, while the remainder have ages