Open Access[O ii ] emitters at z ∼ 4.6 in the GOODS field: a homogeneous measure of evolving star formation
Author(s) -
Bayliss K. D.,
McMahon R. G.,
Venemans B. P.,
Banerji M.,
Lewis J. R.
Publication year - 2012
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2012.21683.x
Subject(s) - physics , star formation , astrophysics , redshift , galaxy , line (geometry) , flux (metallurgy) , homogeneous , emission spectrum , star (game theory) , astronomy , spectral line , geometry , mathematics , materials science , metallurgy , thermodynamics
We present the results of a high‐redshift, z = 4.6, survey of [O ii ] λ3727 emission line galaxies in the GOODS‐S field. The survey uses deep near‐infrared data in the NB2090 (λ c = 2.095 μm, Δ λ = 0.02 μm) and Ks (λ c = 2.146 μm, Δ λ = 0.324 μm) filters taken with the European Southern Observatory instrument, HAWK‐I. The images reach an emission line flux limit (5σ) of 3.16 × 10 −18 erg s −1 cm −2 . At z = 4.6, the survey probes a comoving volume of ∼6680 Mpc 3 . Three [O ii ] emission line candidates at z ∼ 4.6 are selected using the Lyman‐break criteria. Photometric redshift analysis supports the conclusion that these are genuine [O ii ] emitters, ruling out a z < 3 solution entirely for one of the candidates. In the analysis presented in this paper, two scenarios are considered: first, all three candidates are genuine [O ii ] emitters and secondly, only the most likely candidate is a genuine [O ii ] emitter. We use the line fluxes of these objects to place confidence limits on the star formation rate density (SFRD) in bright (log( L [ Oii ]) > 42.0 )[O ii ] emission line galaxies. Assuming an observed [O ii ]/Hα line ratio of 0.45 and A (Hα) = 1.0 mag, we report an SFRD of in our objects. Using small number statistics, we then place a 50 per cent confidence interval on the global star formation rate of . By combining our results with those from low‐ z surveys, we compile the first homogeneous set of measurements of the SFRD in bright [O ii ] emitters from z = 0 to 4.6. From this, we conclude that there was an increase in the SFRD in the brightest [O ii ] emitters of at least a factor of 2 between z = 4.6 and 1.85.