The average physical properties and star formation histories of the UV-brightest star-forming galaxies at z ∼ 3.7

Kyoung Soo Lee, Arjun Dey, Naveen Reddy, Michael J.I. Brown, Anthony H. Gonzalez, Buell T. Jannuzi, Michael C. Cooper, Xiaohui Fan, Fuyan Bian, Eilat Glikman, Daniel Stern, Mark Brodwin, Asantha Cooray

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57 Scopus citations

Abstract

We investigate the average physical properties and star formation histories (SFHs) of the most UV-luminous star-forming galaxies at z ∼ 3.7. Our results are based on the average spectral energy distributions (SEDs), constructed from stacked optical-to-infrared photometry, of a sample of the 1913 most UV-luminous star-forming galaxies found in 5.3 deg2 of the NOAO Deep Wide-Field Survey. We find that the shape of the average SED in the rest optical and infrared is fairly constant with UV luminosity, i.e., more UV-luminous galaxies are, on average, also more luminous at longer wavelengths. In the rest UV, however, the spectral slope β (≡ dlogF λ/dlogλ; measured at 0.13 μm < λrest < 0.28 μm) rises steeply with the median UV luminosity from -1.8 at L ≈ L* to -1.2 (L ≈ 4-5L*). We use population synthesis analyses to derive their average physical properties and find that (1) L UV and thus star formation rates (SFRs) scale closely with stellar mass such that more UV-luminous galaxies are also more massive, (2) the median ages indicate that the stellar populations are relatively young (200-400Myr) and show little correlation with UV luminosity, and (3) more UV-luminous galaxies are dustier than their less-luminous counterparts, such that L ≈ 4-5L* galaxies are extincted up to A(1600) = 2mag while L ≈ L* galaxies have A(1600) = 0.7-1.5mag. We argue that the average SFHs of UV-luminous galaxies are better described by models in which SFR increases with time in order to simultaneously reproduce the tight correlation between the UV-derived SFR and stellar mass and their universally young ages. We demonstrate the potential of measurements of the SFR-M * relation at multiple redshifts to discriminate between simple models of SFHs. Finally, we discuss the fate of these UV-brightest galaxies in the next 1-2Gyr and their possible connection to the most massive galaxies at z ∼ 2.

Original languageEnglish (US)
Article number99
JournalAstrophysical Journal
Volume733
Issue number2
DOIs
StatePublished - Jun 1 2011

Keywords

  • cosmology: observations
  • dust, extinction
  • galaxies: evolution
  • galaxies: formation
  • galaxies: high-redshift
  • galaxies: stellar content

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Lee, K. S., Dey, A., Reddy, N., Brown, M. J. I., Gonzalez, A. H., Jannuzi, B. T., Cooper, M. C., Fan, X., Bian, F., Glikman, E., Stern, D., Brodwin, M., & Cooray, A. (2011). The average physical properties and star formation histories of the UV-brightest star-forming galaxies at z ∼ 3.7. Astrophysical Journal, 733(2), [99]. https://doi.org/10.1088/0004-637X/733/2/99