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A large Hα survey at z = 2.23, 1.47, 0.84 and 0.40: the 11 Gyr evolution of star-forming galaxies from HiZELS

Sobral, David and Smail, Ian and Best, Philip N. and Geach, James E. and Matsuda, Yuichi and Stott, John P. and Cirasuolo, Michele and Kurk, Jaron (2013) A large Hα survey at z = 2.23, 1.47, 0.84 and 0.40: the 11 Gyr evolution of star-forming galaxies from HiZELS. Monthly Notices of the Royal Astronomical Society, 428 (2). pp. 1128-1146. ISSN 0035-8711. doi:10.1093/mnras/sts096.

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This paper presents new deep and wide narrow-band surveys undertaken with United Kingdom Infrared Telescope (UKIRT), Subaru and the Very Large Telescope (VLT), a unique combined effort to select large, robust samples of Hα star-forming galaxies at z = 0.40, 0.84, 1.47 and 2.23 (corresponding to look-back times of 4.2, 7.0, 9.2 and 10.6 Gyr) in a uniform manner over ∼2 deg^2 in the Cosmological Evolution Survey and Ultra Deep Survey fields. The deep multi-epoch Hα surveys reach a matched 3σ flux limit of ≈3 M_⊙ yr^(−1) out to z = 2.2 for the first time, while the wide area and the coverage over two independent fields allow us to greatly overcome cosmic variance and assemble by far the largest samples of Hα emitters. Catalogues are presented for a total of 1742, 637, 515 and 807 Hα emitters, robustly selected at z = 0.40, 0.84, 1.47 and 2.23, respectively, and used to determine the Hα luminosity function and its evolution. The faint-end slope of the Hα luminosity function is found to be α = −1.60 ± 0.08 over z = 0–2.23, showing no significant evolution. The characteristic luminosity of star-forming galaxies, L*_Hα, evolves significantly as log  L*_Hα(z) = 0.45z + log  L*_z = 0. This is the first time Hα has been used to trace star formation activity with a single homogeneous survey at z = 0.4–2.23. Overall, the evolution seen with Hα is in good agreement with the evolution seen using inhomogeneous compilations of other tracers of star formation, such as far-infrared and ultraviolet, jointly pointing towards the bulk of the evolution in the last 11 Gyr being driven by a statistically similar star-forming population across cosmic time, but with a strong luminosity increase from z ∼ 0 to ∼2.2. Our uniform analysis allows us to derive the Hα star formation history (SFRH) of the Universe, showing a clear rise up to z ∼ 2.2, for which the simple parametrization log_10ρSFR = −2.1(1 + z)^(−1) is valid over 80 per cent of the age of the Universe. The results reveal that both the shape and normalization of the Hα SFRH are consistent with the measurements of the stellar mass density growth, confirming that our Hα SFRH is tracing the bulk of the formation of stars in the Universe for z < 2.23. The star formation activity over the last ∼11 Gyr is responsible for producing ∼95 per cent of the total stellar mass density observed locally, with half of that being assembled in 2 Gyr between z = 1.2 and 2.2, and the other half in 8 Gyr (since z < 1.2). If the star formation rate density continues to decline with time in the same way as seen in the past ∼11 Gyr, then the stellar mass density of the Universe will reach a maximum which is only 5 per cent higher than the present-day value.

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Sobral, David0000-0001-8823-4845
Smail, Ian0000-0003-3037-257X
Geach, James E.0000-0003-4964-4635
Additional Information:© 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2012 September 27. Received 2012 September 27; in original form 2012 February 15. First published online: November 7, 2012. This work is based on observations obtained using the Wide Field CAMera (WFCAM) on the 3.8-m United Kingdom Infrared Telescope (UKIRT), as part of the High-redshift(Z) Emission Line Survey (HiZELS; U/CMP/3 and U/10B/07). It also relies on observations conducted with HAWK-I on the ESO Very Large Telescope (VLT), programme 086.7878.A, and observations obtained with Suprime-Cam on the Subaru Telescope (S10B-144S). The authors would like to thank the reviewer, James Colbert, for many comments and suggestions which improved the paper significantly. DS is supported by a NOVA fellowship. IS acknowledges a Leverhulme Senior Fellowship. PNB acknowledges support from the Leverhulme Trust. YM, JPS and IS thank the UK Science and Technology Facility Council (STFC). JEG is supported by a Banting Fellowship, administered by the Natural Science and Engineering Research Council of Canada. We would like to thank Richard Ellis, Simon Lilly, Peter Capak, Adam Muzzin, Taddy Kodama, Masao Hayashi, Andy Lawrence, Joop Schaye,Marijn Franx, Huub Röttgering, Rychard Bouwens and Renske Smit for many interesting and helpful discussions. We would also like to thank Chun Ly for helpful comments. The authors wish to thank all the JAC staff for their help in conducting the observations at the UKIRT telescope and their continuous support, and we are also extremely grateful to all the Subaru staff. We also acknowledge ESO and Subaru for service observations. Finally, the authors fully acknowledge the tremendous work that has been done by both COSMOS and UKIDSS UDS/SXDF teams in assembling such large, state-of-the-art multiwavelength data sets over such wide areas, as those have been crucial for the results presented in this paper.
Funding AgencyGrant Number
Nederlandse Onderzoekschool Voor Astronomie (NOVA)UNSPECIFIED
Leverhulme TrustUNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Subject Keywords:galaxies: evolution; galaxies: high-redshift; galaxies: luminosity function, mass function; cosmology: observations
Issue or Number:2
Record Number:CaltechAUTHORS:20130723-114603121
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:39527
Deposited On:24 Jul 2013 16:50
Last Modified:09 Nov 2021 23:45

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