We present a clustering analysis of 370 high-confidence H \alpha emitters ( HAEs ) at z = 2.23 .
The HAEs are detected in the Hi-Z Emission Line Survey ( HiZELS ) , a large-area blank field 2.121 \mu m narrowband survey using the United Kingdom Infrared Telescope ( UKIRT ) Wide Field Camera ( WFCAM ) .
Averaging the two-point correlation function of HAEs in two \sim 1 degree scale fields ( United Kingdom Infrared Deep Sky Survey/Ultra Deep Survey [ UDS ] and Cosmological Evolution Survey [ COSMOS ] fields ) we find a clustering amplitude equivalent to a correlation length of r _ { 0 } = 3.7 \pm 0.3 h ^ { -1 } Mpc for galaxies with star formation rates of \mathrel { \raise 1.505 pt \hbox { $ \scriptstyle > $ } \kern - 6.0 pt \lower 1.72 pt \hbox { { $% \scriptstyle \sim$ } } } 7 M _ { \odot } yr ^ { -1 } .
The data are well-fitted by the expected correlation function of Cold Dark Matter , scaled by a bias factor : \omega _ { HAE } = b ^ { 2 } \omega _ { DM } where b = 2.4 ^ { +0.1 } _ { -0.2 } .
The corresponding ‘ characteristic ’ mass for the halos hosting HAEs is \log ( M _ { h } / [ h ^ { -1 } M _ { \odot } ] ) = 11.7 \pm 0.1 .
Comparing to the latest semi-analytic galform predictions for the evolution of HAEs in a \Lambda CDM cosmology , we find broad agreement with the observations , with galform predicting a HAE correlation length of \sim 4 h ^ { -1 } Mpc .
Motivated by this agreement , we exploit the simulations to construct a parametric model of the halo occupation distribution ( HOD ) of HAEs , and use this to fit the observed clustering .
Our best-fitting HOD can adequately reproduce the observed angular clustering of HAEs , yielding an effective halo mass and bias in agreement with that derived from the scaled \omega _ { DM } fit , but with the relatively small sample size the current data provide a poor constraint on the HOD .
However , we argue that this approach provides interesting hints into the nature of the relationship between star-forming galaxies and the matter field , including insights into the efficiency of star formation in massive halos .
Our results support the broad picture that ‘ typical ’ ( \mathrel { \raise 1.505 pt \hbox { $ \scriptstyle < $ } \kern - 6.0 pt \lower 1.72 pt \hbox { { $% \scriptstyle \sim$ } } } L ^ { \star } ) star-forming galaxies have been hosted by dark matter haloes with M _ { h } \mathrel { \raise 1.505 pt \hbox { $ \scriptstyle < $ } \kern - 6.0 pt \lower 1.72 pt% \hbox { { $ \scriptstyle \sim$ } } } 10 ^ { 12 } h ^ { -1 } M _ { \odot } since z \approx 2 , but with a broad occupation distribution and clustering that is likely to be a strong function of luminosity .