Abstract
Lyman-break galaxies (LBGs) are a population of distant objects (z ∼ 3) selected at rest-frame UV that represent the typical starburst galaxy at a time when the universe was going through its peak in star formation activity. The star formation rates of LBGs suggest that these galaxies may be the progenitors of a large part of the massive galaxies in the local universe, making them important objects of study. However, detailed studies of the morphology and kinematics of these distant galaxies are limited by the sensitivity of current instruments. We study a sample of low-redshift UV-selected supercompact starbursts that share many properties (morphology, surface brightness, luminosity) with high-redshift LBGs and are hence denominated as Lyman-break Analogs (LBAs). These UV luminous galaxies (UVLGs) were recently uncovered by the Galaxy Evolution Explorer (GALEX) satellite. At significantly lower redshifts (z 0.2) than LBGs, they provide us with a unique opportunity to draw analogies with their high-redshift counterparts and study in great detail the astrophysical conditions that lead to the star formation activity we observe in the distant universe. We have undertaken the near-IR photometric analysis of a sample of LBAs based on observations taken with the Fourstar instrument on the 6.5m Baade Telescope (Las Campanas Observatory, Chile). We now extend this work to the wider population of compact UVLGs, with surface brightness one or two orders of magnitude than normal galaxies, but less extreme than supercompact UVLGs. Based on J, H, Ks, and optical photometry for 40 compact and supercompact UVLGs we are in the process of analyzing the spectral energy distribution (SED) of each individual galaxy to derive stellar masses and ages in order to explore the similarities and differences between these two populations relative to normal galaxies in the local universe and to LBGs in the distant universe.
