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Starbursts and the High-Redshift Universe

By Timothy M. Heckman

Abstract

Starbursts are episodes of intense star-formation that occur in the central regions of galaxies, and dominate the integrated emission from the galaxy. They serve as local analogs of the processes that were important in the origin and early evolution of galaxies and in the heating and chemical enrichment of the inter-galactic medium. They may also play an important role in the AGN phenomenon. In this contribution I review starbursts from this broad perspective, with a specific focus on the use of UV spectroscopic diagnostics that can be ‘calibrated ’ at low-redshift and then applied at high redshift. From the analysis of the UV properties of local starbursts we have learned: 1) dust dramatically affects our view of high-mass star-formation 2) more metal-rich starbursts are redder and more heavily extincted in the UV, more luminous, have stronger vacuum- UV absorption-lines, and occur in more massive and opticallybrighter host galaxies 3) the strong interstellar absorption-lines directly reflect the hydrodynamical consequences of the starburst. These results suggest that the high- redshift ‘Lyman Drop-Out ’ galaxies are typically highly reddened and extincted by dust (average factor of 5 to 10 in the UV), may have moderately high metallicities (0.1 to 1 times solar?), are probably building galaxies with stellar surface-mass-densities similar to present-day ellipticals, and may be suffering substantial losses of metalenriched gas that can ‘pollute ’ the inter-galactic medium. I also discuss UV observations of the nuclei of type 2 Seyfert galaxies. These show that compact (100-pc-scale) heavily-reddened starbursts are the source of most of the ‘featureless continuum ’ in UV-bright Seyfert 2 nuclei, and are an energetically significant component in these objects. 1 2 Timothy M. Heckman

Year: 1998
OAI identifier: oai:CiteSeerX.psu:10.1.1.315.9527
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