Events at Physics
galactic nuclei, but emit much of their light as radiation reprocessed by dust into the far infrared. The most massive starbursts in both the local and high redshift universe are ultraluminous infrared galaxies(L_IR > 1012 Lsun). This class of galaxies was discovered by IRAS and studied extensively with Spitzer. However, it remains controversial what IR-luminous galaxies at z=1 are, and what they will evolve into. Are IR-luminous galaxies at high redshift mostly galaxy mergers, as they are at low redshift? Are ultraluminous IR galaxies strongly clustered, and can we infer whether they must evolve into cluster galaxies today? Is star formation in high-z IR-luminous galaxies centrally concentrated or spatially extended? I will discuss these questions using data from Spitzer/MIPS, HST, and the DEEP2 redshift survey. I will also show near-infrared slitless spectroscopy from the WFC3 instrument on Hubble, and its use as a probe of star-forming galaxies at high redshifts, with some application to measuring extinction and the spatial extent of star formation in high-z galaxies.