Journal Article

The clustering and evolution of Hα emitters at <i>z</i> ∼ 1 from HiZELS*

David Sobral, Philip N. Best, James E. Geach, Ian Smail, Michele Cirasuolo, Timothy Garn, Gavin B. Dalton and Jaron Kurk

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 404, issue 3, pages 1551-1563
Published in print May 2010 | ISSN: 0035-8711
Published online May 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.16364.x
The clustering and evolution of Hα emitters at z ∼ 1 from HiZELS*

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The clustering properties of a well-defined sample of 734 Hα emitters at z= 0.845 ± 0.015, obtained as part of the Hi-z Emission Line Survey, are investigated. The spatial correlation function of these Hα emitters is very well described by the power-law ξ= (r/r0)−1.8, with a real-space correlation, r0, of 2.7 ± 0.3 h−1 Mpc. The correlation length r0 increases strongly with Hα luminosity (L), from r0∼ 2 h−1 Mpc for the most quiescent galaxies [star formation rates (SFRs) of ∼4 M yr−1] up to r0 > 5 h−1 Mpc for the brightest galaxies in Hα. The correlation length also increases with increasing rest-frame K-band (MK) luminosity, but the r0L correlation maintains its full statistical significance at fixed MK. At z= 0.84, star-forming galaxies classified as irregulars or mergers are much more clustered than discs and non-mergers, respectively; however, once the samples are matched in L and MK, the differences vanish, implying that the clustering is independent of morphological type at z∼ 1 just as in the local Universe. The typical Hα emitters found at z= 0.84 reside in dark matter haloes of ≈1012 M, but those with the highest SFRs reside in more massive haloes of ≈1013 M. The results are compared with those of Hα surveys at different redshifts: although the break of the Hα luminosity function L* evolves by a factor of ∼30 from z= 0.24 to 2.23, if the Hα luminosities at each redshift are scaled by L*(z) then the correlation lengths indicate that, independently of cosmic time, galaxies with the same (L)/L*(z) are found in dark matter haloes of similar masses. This not only confirms that the star formation efficiency in high redshift haloes is higher than locally but also suggests a fundamental connection between the strong negative evolution of L* since z= 2.23 and the quenching of star formation in galaxies residing within dark matter haloes significantly more massive than 1012 M at any given epoch.

Keywords: galaxies: evolution; galaxies: haloes; galaxies: high-redshift; cosmology: observations; large-scale structure of Universe

Journal Article.  11282 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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