Boötes-HiZELS: An optical to near-infrared survey of emission-line galaxies at z = 0.4 − 4.7

Jorryt Matthee, David Sobral, Philip Best, Ian Smail, Fuyan Bian, Behnam Darvish, Huub Röttgering, Xiaohui Fan

Research output: Contribution to journalArticlepeer-review


We present a sample of ∼ 1000 emission line galaxies at z = 0.4 − 4.7 from the ∼ 0.7deg2 High-z Emission Line Survey (HiZELS) in the Boötes field identified with a suite of six narrow-band filters at ≈ 0.4−2.1 µm. These galaxies have been selected on their Lyα (73), [Oii] (285), Hβ/[Oiii] (387) or Hα (362) emission-line, and have been classified with optical to near-infrared colours. A subsample of 98 sources have reliable redshifts from multiple narrow-band (e.g. [Oii]-Hα) detections and/or spectroscopy. In this survey paper, we present the observations, selection and catalogs of emitters. We measure number densities of Lyα, [Oii], Hβ/[Oiii] and Hα and confirm strong luminosity evolution in star-forming galaxies from z ∼ 0.4 to ∼ 5, in agreement with previous results. To demonstrate the usefulness of dual-line emitters, we use the sample of dual [Oii]-Hα emitters to measure the observed [Oii]/Hα ratio at z = 1.47. The observed [Oii]/Hα ratio increases significantly from 0.40±0.01 at z = 0.1 to 0.52±0.05 at z = 1.47, which we attribute to either decreasing dust attenuation with redshift, or due to a bias in the (typically) fiber-measurements in the local Universe which only measure the central kpc regions. At the bright end, we find that both the Hα and Lyα number densities at z ≈ 2.2 deviate significantly from a Schechter form, following a power-law. We show that this is driven entirely by an increasing X-ray/AGN fraction with line-luminosity, which reaches ≈ 100 % at line-luminosities L & 3 ×1044 erg s1.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Feb 15 2017


  • Galaxies: active
  • Galaxies: evolution
  • Galaxies: high-redshift
  • Galaxies: luminosity function
  • Galaxies: star formation
  • Mass function

ASJC Scopus subject areas

  • General

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