Optical-IR Spectral Energy Distributions of z>2 Galaxies

Abstract

Broadband optical and IR spectral energy distributions are determined for spectroscopically confirmed z>2 Lyman break objects in the Hubble Deep Field. These photometric data are compared to spectral synthesis models which take into account the effects of metallicity and of internal reddening due to dust. It is found that, on average, Lyman break objects are shrouded in enough dust (typically $E(B-V)~0.3) to suppress their UV fluxes by a factor of ~20. Furthermore, these objects are dominated by very young (<0.2 Gyr) stellar populations, suggesting that star formation at high redshift is episodic rather than continuous.