Thursday, June 21, 2012

1206.4303 (Chun Ly et al.)

The Stellar Population and Star Formation Rates of z~1.5-1.6 [O II] Emitting Galaxies Selected from Narrow-Band Emission-Line Surveys    [PDF]

Chun Ly, Matthew A. Malkan, Nobunari Kashikawa, Masao Hayashi, Tohru Nagao, Kazuhiro Shimasaku, Kazuaki Ota, Nathaniel R. Ross
We present the first detailed study of the stellar populations of star-forming galaxies at z~1.5, which are selected by their [O II] emission line, detected in narrow-band surveys. We identified ~1,300 [O II] emitters at z=1.47 and z=1.62 in the Subaru Deep Field with rest-frame EWs above 13\AA. Optical and near-infrared spectroscopic observations for ~10% of our samples show that our two-color identification of [O II] emission-line galaxies is 99% successful. We analyze the multi-wavelength properties of a subset of ~1,200 galaxies with the best photometry. They have average rest-frame EW of 45\AA, stellar mass of 3 x 10^9 M_sun, and stellar age of 100 Myr. In addition, our SED fitting and broad-band colors indicate that [O II] emitters span the full range of galaxy populations at z~1.5. We also find that 80% of [O II] emitters are also photometrically classified as "BX/BM" (UV) galaxies and/or the star-forming "BzK" (near-IR) galaxies. Our [O II] emission line survey produces a far more complete, and somewhat deeper sample of z~1.5 galaxies than either the BX/BM or sBzK selection alone. We constructed average SEDs and find that higher [O II] EW galaxies have somewhat bluer continua. SED model-fitting shows that they have on average half the stellar mass of galaxies with lower [O II] EW. The observed [O II] luminosity is well-correlated with the far-UV continuum with a slope slightly less than one (0.89). However, this offset is only marginally significant (< 1\sigma). The fit also suggests that [O II] can be used as a SFR indicator, but with an additional systematic uncertainty of ~0.2 dex.
View original: http://arxiv.org/abs/1206.4303

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