  The deep, near-infrared narrow-band survey HiZELS has yielded robust samples
of H-alpha emitting star-forming galaxies within narrow redshift slices at z =
0.8, 1.47 and 2.23. In this paper, we distinguish the stellar mass and
star-formation rate (SFR) dependence of the clustering of these galaxies. At
high stellar masses (M/M_sol>2x10^10), where HiZELS selects galaxies close to
the so-called star-forming main sequence, the clustering strength is observed
to increase strongly with stellar mass (in line with the results of previous
studies of mass-selected galaxy samples) and also with SFR. These two
dependencies are shown to hold independently. At lower stellar masses, however,
where HiZELS probes high specific SFR galaxies, there is little or no
dependence of the clustering strength on stellar mass, but the dependence on
SFR remains: high-SFR low-mass galaxies are found in more massive dark matter
haloes than their lower SFR counterparts. We argue that this is due to
environmentally driven star formation in these systems. We apply the same
selection criteria to the EAGLE cosmological hydrodynamical simulations. We
find that, in EAGLE, the high-SFR low-mass galaxies are central galaxies in
more massive dark matter haloes, in which the high SFRs are driven by a
(halo-driven) increased gas content.
