The Nature of Hβ+[Oiii] and [Oii] emitters to z ∼ 5 with HiZELS : stellar mass functions and the evolution of EWs

Khostovan, Ali Ahmad and Sobral, David and Mobasher, Bahram and Smail, Ian and Darvish, Behnam and Nayyeri, Hooshang and Hemmati, Shoubaneh and Stott, John (2016) The Nature of Hβ+[Oiii] and [Oii] emitters to z ∼ 5 with HiZELS : stellar mass functions and the evolution of EWs. Monthly Notices of the Royal Astronomical Society, 463 (3). pp. 2363-2382. ISSN 0035-8711

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We investigate the properties of ∼ 7000 narrow-band selected galaxies with strong Hβ+[Oiii] and [Oii] nebular emission lines from the High-z Emission Line Survey (HiZELS) between z ∼ 0.8 − 5.0. Our sample covers a wide range in stellar mass (Mstellar ∼ 107.5−12.0 M), rest-frame equivalent widths (EWrest∼ 10 − 105 ˚A), and line luminosities (Lline ∼ 1040.5−43.2 erg s−1 ). We measure the Hβ+[Oiii]-selected stellar mass functions out to z ∼ 3.5 and find that both M? and φ? increases with cosmic time, which may be due to the [Oiii] selection including an increasing fraction of AGN at lower redshifts. The [Oii]-selected stellar mass functions show a constant M? ≈ 1011.6 M and a strong, increasing evolution with cosmic time in φ? in line with Hα studies. We also investigate the evolution of the EWrest as a function of redshift with a fixed mass range (109.5−10.0 M) and find an increasing trend best represented by (1 + z) 3.81±0.14 and (1 + z) 2.72±0.19 up to z ∼ 2 and z ∼ 3 for Hβ+[Oiii] and [Oii] emitters, respectively. This is the first time that the EWrest evolution has been directly measured for Hβ+[Oiii] and [Oii] emitters up to these redshifts. There is evidence for a slower evolution for z > 2 in the Hβ+[Oiii] EWrest and a decreasing trend for z > 3 in the [Oii] EWrest evolution, which would imply low [Oii] EW at the highest redshifts and higher [Oiii]/[Oii] line ratios. This suggests that the ionization parameter at higher redshift may be significantly higher than the local Universe. Our results set the stage for future near-IR space-based spectroscopic surveys to test our extrapolated predictions and also produce z > 5 measurements to constrain the high-z end of the EWrest and [Oiii]/[Oii] evolution.

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Journal Article
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Monthly Notices of the Royal Astronomical Society
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This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version A. A. Khostovan, D. Sobral, B. Mobasher, I. Smail, B. Darvish, H. Nayyeri, S. Hemmati, and J. P. Stott The nature of Hβ+[O III] and [O II] emitters to z ∼ 5 with HiZELS: stellar mass functions and the evolution of EWs MNRAS (December 11, 2016) Vol. 463 2363-2382 doi:10.1093/mnras/stw2174 first published online September 1, 2016 is available online at:
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?? astro-ph.gaastronomy and astrophysicsspace and planetary science ??
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14 Jul 2016 15:24
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21 Apr 2024 23:56