Journal Article

HiZELS: a high-redshift survey of Hα emitters – I. The cosmic star formation rate and clustering at <i>z</i>= 2.23*

J. E. Geach, Ian Smail, P. N. Best, J. Kurk, M. Casali, R. J. Ivison and K. Coppin

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 388, issue 4, pages 1473-1486
Published in print August 2008 | ISSN: 0035-8711
Published online August 2008 | e-ISSN: 1365-2966 | DOI:
HiZELS: a high-redshift survey of Hα emitters – I. The cosmic star formation rate and clustering at z= 2.23*

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We present results from a near-infrared narrow-band survey of emission-line galaxies at z= 2.23, using the Wide Field Camera on the United Kingdom Infrared Telescope. The H2S1 narrow-band filter (λc= 2.121 μm) we employ selects the Hα emission-line redshifted to z= 2.23, and is thus suitable for selecting ‘typical’ star-forming galaxies and active galactic nuclei at this epoch. The pilot study was undertaken in the well-studied Cosmological Evolution Survey field (COSMOS) and is already the largest near-infrared narrow-band survey at this depth, with a line flux limit of F∼ 10−16erg s−1cm−2 over 0.60 deg2, probing ∼220 × 103Mpc3 (comoving) down to a limiting star formation rate of ∼30 M yr−1 (3σ). In this paper, we present the results from our pilot survey and evaluate the Hα luminosity function and estimate the clustering properties of Hα emitters at z= 2.23 from 55 detected galaxies. The integrated luminosity function is used to estimate the volume-averaged star formation rate at z= 2.23: ρSFR= 0.17+0.16−0.09 M yr−1Mpc−3 for L > 1042erg s−1. For the first time, we use the Hα star formation tracer to reliably constrain ρSFR out to z= 2.23 demonstrating the rapid increase in ρSFR out to this redshift as well as confirming the flattening in ρSFR between z∼ 1 and 2. In addition to the luminosity distribution, we analyse the clustering properties of these galaxies. Using the two-point angular correlation function, ω(θ), we estimate a real-space correlation length of r0= 4.2+0.4−0.2 h−1Mpc. In comparison to models of clustering which take into account bias evolution, we estimate that these galaxies are hosted by dark matter haloes of mass Mhalo∼ 1012M consistent with the progenitors of the Milky Way.

Keywords: galaxies: evolution; galaxies: high-redshift; galaxies: luminosity function, mass function; cosmology: observations

Journal Article.  12379 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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