Kavli Affiliate: Roberto Maiolino
| First 5 Authors: Aayush Saxena, Andrew J. Bunker, Gareth C. Jones, Daniel P. Stark, Alex J. Cameron
| Summary:
We present the properties of 17 faint Ly$alpha$ emitting galaxies (LAEs) at
$z>5.8$ from the JWST Advanced Deep Extragalactic Survey (JADES) in the Hubble
Ultra Deep Field/GOODS-S. These LAEs span a redshift range $zapprox5.8-8.0$
and a UV magnitude range $M_{UV}approx-17$ to $-20.6$, with the Ly$alpha$
equivalent width (EW) in the range $approx 25-350$ AA. The detection of other
rest-optical emission lines in the spectra of these LAEs enables the
determination of accurate systemic redshifts and Ly{alpha} velocity offsets,
as well as the physical and chemical composition of their stars and
interstellar media. These faint LAEs are consistent with metal-poor systems
with high ionization parameters, similar to the general galaxy population at
$z>6$. We measured an average ionizing photon production efficiency,
log($xi_rm{ion}$/erg$^{-1}$ Hz) $approx25.57$ across our LAEs, which does
not evolve strongly with redshift. We report an anti-correlation between the
Ly$alpha$ escape fraction (f_rm{esc}) and the velocity offset from systemic
redshift, consistent with model expectations. We further find that the strength
and velocity offset of Ly$alpha$ are neither correlated with galaxy
spectroscopic properties nor with $xi_rm{ion}$. We find a decrease in
$f_rm{esc}$(Ly$alpha$) with redshift, indicative of decreasing sizes of
ionized bubbles around LAEs at high redshifts. We used a range of galaxy
properties to predict Lyman continuum $f_rm{esc}$ for our LAEs, finding that
the ionizing photon output into the intergalactic medium remains roughly
constant across the observed Ly$alpha$ EW, showing a mild increase at fainter
M$_{UV}$ and at higher redshifts. We derived correlations between the ionizing
photon output from LAEs and $M_{UV}$, Ly$alpha$ EW and redshifts, which can be
used to constrain the ionizing photon contribution of LAEs at $z > 6$ towards
cosmic reionization.
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