TY - JOUR
T1 - The average physical properties and star formation histories of the UV-brightest star-forming galaxies at z ∼ 3.7
AU - Lee, Kyoung Soo
AU - Dey, Arjun
AU - Reddy, Naveen
AU - Brown, Michael J.I.
AU - Gonzalez, Anthony H.
AU - Jannuzi, Buell T.
AU - Cooper, Michael C.
AU - Fan, Xiaohui
AU - Bian, Fuyan
AU - Glikman, Eilat
AU - Stern, Daniel
AU - Brodwin, Mark
AU - Cooray, Asantha
PY - 2011/6/1
Y1 - 2011/6/1
N2 - 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.
AB - 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.
KW - cosmology: observations
KW - dust, extinction
KW - galaxies: evolution
KW - galaxies: formation
KW - galaxies: high-redshift
KW - galaxies: stellar content
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UR - http://www.scopus.com/inward/citedby.url?scp=79956351648&partnerID=8YFLogxK
U2 - 10.1088/0004-637X/733/2/99
DO - 10.1088/0004-637X/733/2/99
M3 - Article
AN - SCOPUS:79956351648
SN - 0004-637X
VL - 733
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 99
ER -