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CF-HiZELS, an ∼10deg2 emission-line survey with spectroscopic follow-up: Hα, [O iii]+Hβ and [Oii] luminosity functions at z=

D. Sobral, J. Matthee, P. Best, I. Smail, A. A. Khostovan, B. Milvang-Jensen, J.-W. Kim, J. P. Stott, J. Calhau, H. Nayyeri, B. Mobasher

Abstract
We present results from the largest contiguous narrow-band survey in the near-infrared. We have used the wide-field infrared camera/Canada–France–Hawaii Telescope and the lowOH2 filter (1.187 ± 0.005 μm) to survey ≈10 deg2 of contiguous extragalactic sky in the SA22 field. A total of ∼6000 candidate emission-line galaxies are found. We use deep ugrizJK data to obtain robust photometric redshifts. We combine our data with the High-redshift(Z) Emission Line Survey (HiZELS), explore spectroscopic surveys (VVDS, VIPERS) and obtain our own spectroscopic follow-up with KMOS, FMOS and MOSFIRE to derive large samples of high-redshift emission-line selected galaxies: 3471 Hα emitters at z = 0.8, 1343 [O iii] + Hβ emitters at z = 1.4 and 572 [O ii] emitters at z = 2.2. We probe comoving volumes of >106 Mpc3 and find significant overdensities, including an 8.5σ (spectroscopically confirmed) overdensity of Hα emitters at z = 0.81. We derive Hα, [O iii] + Hβ and [O ii] luminosity functions at z = 0.8, 1.4, 2.2, respectively, and present implications for future surveys such as Euclid. Our uniquely large volumes/areas allow us to subdivide the samples in thousands of randomized combinations of areas and provide a robust empirical measurement of sample/cosmic variance. We show that surveys for star-forming/emission-line galaxies at a depth similar to ours can only overcome cosmic-variance (errors <10 per="" cent="" if="" they="" are="" based="" on="" volumes="">5 × 105 Mpc3; errors on L* and ϕ* due to sample (cosmic) variance on surveys probing ∼104 and ∼105 Mpc3 are typically very high: ∼300 and ∼40–60 per cent, respectively.

Keywords
galaxies: evolution - galaxies: formation - galaxies: luminosity function, mass function - cosmology: observations - early Universe - large-scale structure of Universe

Monthly Notices of the Royal Astronomical Society
Volume 451, Issue 3, Page 2303
2015 June

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia