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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 448294.0, MPI für Astronomie / Publikationen_mpia
HiZELS: a high-redshift survey of Halpha emitters - II. The nature of star-forming galaxies at z = 0.84
Authors:Sobral, D.; Best, P. N.; Geach, J. E.; Smail, Ian; Kurk, J.; Cirasuolo, M.; Casali, M.; Ivison, R. J.; Coppin, K.; Dalton, G. B.
Date of Publication (YYYY-MM-DD):2009
Title of Journal:Monthly Notices of the Royal Astronomical Society
Journal Abbrev.:MNRAS
Start Page:75
End Page:90
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:New results from a large survey of Halpha emission-line galaxies at z = 0.84 using the Wide Field Camera on the United Kingdom Infrared Telescope and a custom narrow-band filter in the J band are presented as part of the High-z Emission Line Survey (HiZELS). The deep narrow-band images reach an effective flux limit of FHalpha ~ 10-16ergs-1cm-2 in a comoving volume of 1.8 × 105Mpc3, resulting in the largest and deepest survey of its kind ever done at z ~ 1. There are 1517 potential line emitters detected across ~1.4 deg2, of which 743 are selected as Halpha emitters, based on their photometric and spectroscopic redshifts. These are then used to calculate the Halpha luminosity function, which is well fitted by a Schechter function with L* = 1042.26+/-0.05ergs-1, phi* = 10-1.92+/-0.10Mpc-3 and alpha = -1.65 +/- 0.15, and are used to estimate the volume average star formation rate (SFR) at z = 0.845, rhoSFR: 0.15 +/- 0.01Msolaryr-1Mpc-3 (corrected for 15 per cent active galactic nucleus contamination and integrated down to 2.5Msolaryr-1). These results robustly confirm a strong evolution of rhoSFR from the present day out to z ~ 1 and then flattening to z ~ 2 using a single star formation indicator: Halpha luminosity. Out to z ~ 1, both the characteristic luminosity and space density of the Halpha emitters increase significantly; at higher redshifts, L* continues to increase, but phi* decreases. The z = 0.84 Halpha emitters are mostly disc galaxies (82 +/- 3 per cent), while 28 +/- 4 per cent of the sample shows signs of merger activity; mergers account for ~20 per cent of the total integrated rhoSFR at this redshift. Irregulars and mergers dominate the Halpha luminosity function above L*, while discs are dominant at fainter luminosities. These results demonstrate that it is the evolution of `normal' disc galaxies that drives the strong increase in the SFR density from the current epoch to z ~ 1, although the continued strong evolution of L* beyond z = 1 suggests an increasing importance of merger activity at higher redshifts. Based on observations obtained with the Wide Field CAMera (WFCAM) on the United Kingdom Infrared Telescope (UKIRT). E-mail: drss@roe.ac.uk
Free Keywords:galaxies: evolution; galaxies: high-redshift; galaxies: luminosity function; cosmology: observations
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2009MNRAS.398...75S [ID No:1]
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