Mid-Infrared Observations of Extended Lyman-Alpha Halos at High Redshift
Deep narrow-band surveys have detected an enigmatic population of extended Lyman-alpha emitting nebulae at high redshift. These so-called Lyman-alpha Blobs (LABs) have projected physical extents of up to 200 kpc and Lyman-alpha luminosities of 10^44 ergs/s, but the mechanism powering their ionization remains unclear. They are prevalent in high-density regions which exhibit signs of intense star formation and nucleic activity and indeed the largest sample to date lies within in the SSA22 filament at z = 3.09. I will discuss the results of the first large mid-infrared study of this region using deep Spitzer IRAC and MIPS imaging. Through a study of the rest-frame optical and near-infrared spectral energy distributions of LABs I will show that many of these systems are ULIRG-like, with tentative indications of AGN activity, and are distinct from the more moderate star forming population of Lyman-break galaxies in the SSA22 structure. I will close with the implications of these results for the formation mechanism of LABs within the context of galaxy evolution.
Date: Thursday, 27 November 2008 Time: 12:15 Where: Université de Montréal Pavillon Roger-Gaudry, Local D-460 Contact: Pierre Bergeron