The clustering and evolution of Hα emitters at z ∼ 1 from HiZELS☆

The clustering properties of a well-defined sample of 734 H alpha 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 H alpha emitters is very well described by the power-law xi = (r/r(0))-1.8, with a real-space correlation, r(0), of 2.7 +/- 0.3 h-1 Mpc. The correlation length r(0) increases strongly with H alpha luminosity (L-H alpha), from r(0) similar to 2 h-1 Mpc for the most quiescent galaxies [star formation rates (SFRs) of similar to 4 M-circle dot yr-1] up to r(0) > 5 h-1 Mpc for the brightest galaxies in H alpha. The correlation length also increases with increasing rest-frame K-band (M-K) luminosity, but the r(0)-L-H alpha correlation maintains its full statistical significance at fixed M-K. 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-H alpha and M-K, the differences vanish, implying that the clustering is independent of morphological type at z similar to 1 just as in the local Universe. The typical H alpha emitters found at z = 0.84 reside in dark matter haloes of approximate to 1012 M-circle dot, but those with the highest SFRs reside in more massive haloes of approximate to 1013 M-circle dot. The results are compared with those of H alpha surveys at different redshifts: although the break of the H alpha luminosity function L*(H alpha) evolves by a factor of similar to 30 from z = 0.24 to 2.23, if the H alpha luminosities at each redshift are scaled by L*(H alpha)(z) then the correlation lengths indicate that, independently of cosmic time, galaxies with the same (L-H alpha)/L*(H alpha)(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*(H alpha) since z = 2.23 and the quenching of star formation in galaxies residing within dark matter haloes significantly more massive than 1012 M-circle dot at any given epoch.