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Paper: Young Galaxies in the Early Universe: The Physical Properties of Luminous z~5 LBGs Derived from Their Rest-frame UV to Visible SEDs
Volume: 380, At the Edge of the Universe: Latest Results from the Deepest Astronomical Surveys
Page: 75
Authors: Verma, A.; Lehnert, M.; Foerster-Schreiber, N.; Bremer, M.; Douglas, L.
Abstract: High redshift galaxies play a key role in our developing understanding of galaxy formation and evolution. Since such galaxies are being studied within a Gyr after the big bang they provide a unique probe of the physics of one of the first generations of large-scale star-formation. We describe a study of high redshift galaxies selected from the deep, multiwavelength GOODS survey in the Chandra Deep Field South. Using the Lyman-break technique we have identified a robust sample of z~5 UV luminous star-forming galaxies for which we present a complete statistical study of their physical properties as derived from their rest-frame UV-to-visible SEDs. The characteristic properties of this sample differ from LBGs at z~3 of comparable luminosity in that they are a factor of ten less massive (~few×109 M) and the majority (~70%) are considerably younger (<100 Myr). We estimate the contribution of this young population to the global star formation rate and stellar mass density of the universe at z~5. The constraint derived for the latter is affected by their young ages and short duty cycles which imply z~5 LBG samples may be highly incomplete. These intense starbursts have high unobscured star formation rate intensities (~100s M yr−1 kpc−2), suggesting they drive outflows and winds that enrich the intra- and inter-galactic media with metals. These properties imply that the majority of z~5 LBGs are ‘in formation’ meaning that most of their star-formation has likely occurred during the last few crossing times. They are experiencing their first (few) generations of large-scale star formation and are accumulating their first significant stellar mass. As such, z~5 LBGs are the likely progenitors of the spheroidal components of present-day massive galaxies (supported by their high stellar mass surface densities and their core phase-space densities).
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