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Star formation at z=1.47 from HiZELS : an Hα+ [O II] double-blind study

Sobral, D.; Best, P.N.; Matsuda, Y.; Smail, I.; Geach, J.E.; Cirasuolo, M.

Star formation at z=1.47 from HiZELS : an Hα+ [O II] double-blind study Thumbnail


Authors

D. Sobral

P.N. Best

Y. Matsuda

J.E. Geach

M. Cirasuolo



Abstract

This paper presents the results from the first wide and deep dual narrow-band survey to select Hα and [O II] line emitters at z= 1.47 ± 0.02, exploiting synergies between the United Kingdom Infrared Telescope and the Subaru telescope by using matched narrow-band filters in the H and z′ bands. The Hα survey at z= 1.47 reaches a 3σ flux limit of FHα≈ 7 × 10−17 erg s−1 cm−2 (corresponding to a limiting star formation rate (SFR) in Hα of ≈7 M⊙ yr−1) and detects ≈200 Hα emitters over 0.7 deg2, while the much deeper [O II] survey reaches an effective flux of ≈7 × 10−18 erg s−1 cm−2 (SFR in [O II] of ∼1 M⊙ yr−1), detecting ≈1400 z= 1.47 [O II] emitters in a matched comoving volume of ∼2.5 × 105 Mpc3. The combined survey results in the identification of 190 simultaneous Hα and [O II] emitters at z= 1.47. Hα and [O II] luminosity functions are derived and both are shown to evolve significantly from z∼ 0 in a consistent way. The SFR density of the Universe at z= 1.47 is evaluated, with the Hα analysis yielding ρSFR= 0.16 ± 0.05 M⊙ yr−1 Mpc−3 and the [O II] analysis ρSFR= 0.17 ± 0.04 M⊙ yr−1 Mpc−3. The measurements are combined with other studies, providing a self-consistent measurement of the star formation history of the Universe over the last ∼11 Gyr. By using a large comparison sample at z∼ 0.1, derived from the Sloan Digital Sky Survey (SDSS), [O II]/Hα line ratios are calibrated as probes of dust extinction. Hα emitters at z∼ 1.47 show on average AHα≈ 1 mag, the same as found by SDSS in the local Universe. It is shown that although dust extinction correlates with SFR, the relation evolves by about ∼0.5 mag from z∼ 1.5 to ∼0, with local relations overpredicting the dust extinction corrections at high z by that amount. Stellar mass is found to be a much more fundamental extinction predictor, with the same relation between mass and dust extinction being valid at both z∼ 0 and ∼1.5, at least for low and moderate stellar masses. The evolution in the extinction–SFR relation is therefore interpreted as being due to the evolution in median specific SFRs over cosmic time. Dust extinction corrections as a function of optical colours are also derived and shown to be broadly valid at both z∼ 0 and ∼1.5, offering simpler mechanisms for estimating extinction in moderately star-forming systems over the last ∼9 Gyr.

Citation

Sobral, D., Best, P., Matsuda, Y., Smail, I., Geach, J., & Cirasuolo, M. (2012). Star formation at z=1.47 from HiZELS : an Hα+ [O II] double-blind study. Monthly Notices of the Royal Astronomical Society, 420(3), 1926-1945. https://doi.org/10.1111/j.1365-2966.2011.19977.x

Journal Article Type Article
Publication Date Mar 1, 2012
Deposit Date May 10, 2013
Publicly Available Date Mar 29, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 420
Issue 3
Pages 1926-1945
DOI https://doi.org/10.1111/j.1365-2966.2011.19977.x
Keywords Galaxies: evolution, Galaxies: high-redshift, Galaxies: luminosity function, Mass function, Cosmology: observations.

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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS Published by Oxford University Press on behalf of Royal Astronomical Society. All rights reserved.





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