Abstract
We present average stellar population properties and dark matter halo masses
of $z 2$ Ly$\alpha$ emitters (LAEs) from SED fitting to stacked images and
clustering analysis, respectively, using $\simeq$ $1250$ $NB387łe25.5$ objects
in four separate fields of $1$ deg$^2$ in total. With an average stellar
mass of $10.2\, \pm\, 3.010^8\ M_ødot$ and star formation
rate of $3.4\, \pm\, 0.7\ M_ødot\ yr^-1$, the LAEs lie on a
low-mass extrapolation of the star-formation main sequence (MS) with moderate
star formation. Their effective dark matter halo mass is estimated to be
$4.0_-2.9^+5.1 10^10\ M_ødot$ with $b_g,\, eff^\rm
ave = 1.22^+0.16_-0.18$, which is lower than that of $z 2$ LAEs
($b_g,\, eff = 1.8\, \pm\, 0.3$) obtained by a previous study based on a
three times smaller area with a probability of $96\%$, although this difference
can be explained if the cosmic variance in these $b_g,\, eff$ is taken
into account. Such a low halo mass, if it implies a low HI gas mass, is
consistent with high Ly$\alpha$ escape fractions of LAEs observed. Despite the
low halo mass and being in the MS mode, our LAEs have a relatively high
stellar-to-halo mass ratio (SHMR) and baryon conversion efficiency, converting
baryons into stars efficiently until the observed time. The extended
Press-Schechter formalism predicts that at $z=0$ our LAEs are typically
embedded in halos with masses similar to that of the Large Magellanic Cloud
(LMC); if their SFRs are largely suppressed after $z 2$ as reported for
the LMC itself, they will also have similar SHMRs to the LMC.
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