The nature of Hβ+[O iii] and [O ii] emitters to z ∼ 5 with HiZELS: stellar mass functions and the evolution of EWs

• Published in: Monthly notices of the Royal Astronomical Society Vol. 463; no. 3; p. 2363
• Main Authors: Khostovan, A A, Sobral, D, Mobasher, B, Smail, I, Darvish, B, Nayyeri, H, Hemmati, S, Stott, J P
• Format: Journal Article
• Language: English
• Published: 01.12.2016
• Subjects: Emitters; Evolution; Ionization; Red shift; Rest; Stellar mass; Trends
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stw2174

We investigate the properties of ~7000 narrow-band selected galaxies with strong H beta +[OIII] and [OII] nebular emission lines from the High-z Emission-Line Survey between z ~ 0.8 and 5.0. Our sample covers a wide range in stellar mass (...), rest-frame equivalent widths (...), and line luminosities (...). We measure the H beta +[OIII]-selected stellar mass functions out to z ~ 3.5 and find that both ... and ... increases with cosmic time. The [OII]-selected stellar mass functions show a constant ... and a strong, increasing evolution with cosmic time in ... in line with H alpha studies. We also investigate the evolution of the EW sub( rest) as a function of redshift with a fixed mass range (...) and find an increasing trend best represented by ... and ... up to z ~ 2 and ~3 for H beta +[OIII] and [OII] emitters, respectively. This is the first time that the EW sub( rest) evolution has been directly measured for H beta +[OIII] and [OII] emitters up to these redshifts. There is evidence for a slower evolution for z > 2 in the H beta +[OIII] EW sub( rest) and a decreasing trend for z > 3 in the [OII] EW sub( rest) 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 EW sub( rest) and [OIII]/[OII] evolution. (ProQuest: ... denotes formulae/symbols omitted.)