The fraction of Lyman-$\alpha$ emitters among the galaxy population has been
found to increase from $z\sim0$ to $z\sim6$ and drop dramatically at $z>6$.
This drop has been interpreted as an effect of an increasingly neutral
intergalactic medium with increasing redshift, while a LyC escape fraction
evolving with redshift. We report the result of a large VLT/FORS2 program
aiming to confirm spectroscopically a large galaxy sample at $z\geq6$ that has
been selected in several independent fields through the Lyman Break technique.
Combining those data with archival data, we create a large and homogeneous
sample of $z\sim6$ galaxies ($N=127$), complete in terms of Ly$\alpha$
detection at $>95\%$ for EW(Ly$\alpha)\geq25\AA$. We use this sample to derive
a new measurement of the LAE fraction at $z\sim6$ and derive the physical
properties of these galaxies through spectral energy distribution fitting. We
find a median LAE fraction at $z\sim6$ lower than in previous studies. The main
difference between LAEs and non-LAEs is that the latter are significantly
dustier. Using predictions of our SED fitting code accounting for nebular
emission, we find an effective Ly$\alpha$ escape fraction
$f^eff_esc(Ly\alpha)=0.23^+0.36_-0.17$ remarkably consistent with the
value derived by comparing UV luminosity function with Ly$\alpha$ luminosity
function. We conclude that the drop in the LAE fraction from $z\sim6$ to $z>6$
is less dramatic than previously found and the effect of an increasing IGM
neutral fraction is possibly observed at $5<z<6$. Based on our derived
$f^eff_esc(Ly\alpha)$, we find that the IGM has a relatively small impact
on Ly$\alpha$ photon visibility at $z\sim6$, with a lower limit for the IGM
transmission to łya\ photons, $T_IGM\gtrsim0.20$, likely due to the presence
of outflows. abdridged
Description
[1710.01784] A VLT/FORS2 view at $z\sim6$: Lyman-$\alpha$ emitter fraction and galaxy physical properties at the edge of the epoch of cosmic reionization
%0 Generic
%1 debarros2017vltfors2
%A De Barros, S.
%A Pentericci, L.
%A Vanzella, E.
%A Castellano, M.
%A Fontana, A.
%A Grazian, A.
%A Conselice, C. J.
%A Yan, H.
%A Koekemoer, A.
%A Cristiani, S.
%A Dickinson, M.
%A Finkelstein, S. L.
%A Maiolino, R.
%D 2017
%K IGM Lya emitter fraction high-z reionization
%T A VLT/FORS2 view at $z\sim6$: Lyman-$\alpha$ emitter fraction and galaxy
physical properties at the edge of the epoch of cosmic reionization
%U http://arxiv.org/abs/1710.01784
%X The fraction of Lyman-$\alpha$ emitters among the galaxy population has been
found to increase from $z\sim0$ to $z\sim6$ and drop dramatically at $z>6$.
This drop has been interpreted as an effect of an increasingly neutral
intergalactic medium with increasing redshift, while a LyC escape fraction
evolving with redshift. We report the result of a large VLT/FORS2 program
aiming to confirm spectroscopically a large galaxy sample at $z\geq6$ that has
been selected in several independent fields through the Lyman Break technique.
Combining those data with archival data, we create a large and homogeneous
sample of $z\sim6$ galaxies ($N=127$), complete in terms of Ly$\alpha$
detection at $>95\%$ for EW(Ly$\alpha)\geq25\AA$. We use this sample to derive
a new measurement of the LAE fraction at $z\sim6$ and derive the physical
properties of these galaxies through spectral energy distribution fitting. We
find a median LAE fraction at $z\sim6$ lower than in previous studies. The main
difference between LAEs and non-LAEs is that the latter are significantly
dustier. Using predictions of our SED fitting code accounting for nebular
emission, we find an effective Ly$\alpha$ escape fraction
$f^eff_esc(Ly\alpha)=0.23^+0.36_-0.17$ remarkably consistent with the
value derived by comparing UV luminosity function with Ly$\alpha$ luminosity
function. We conclude that the drop in the LAE fraction from $z\sim6$ to $z>6$
is less dramatic than previously found and the effect of an increasing IGM
neutral fraction is possibly observed at $5<z<6$. Based on our derived
$f^eff_esc(Ly\alpha)$, we find that the IGM has a relatively small impact
on Ly$\alpha$ photon visibility at $z\sim6$, with a lower limit for the IGM
transmission to łya\ photons, $T_IGM\gtrsim0.20$, likely due to the presence
of outflows. abdridged
@misc{debarros2017vltfors2,
abstract = {The fraction of Lyman-$\alpha$ emitters among the galaxy population has been
found to increase from $z\sim0$ to $z\sim6$ and drop dramatically at $z>6$.
This drop has been interpreted as an effect of an increasingly neutral
intergalactic medium with increasing redshift, while a LyC escape fraction
evolving with redshift. We report the result of a large VLT/FORS2 program
aiming to confirm spectroscopically a large galaxy sample at $z\geq6$ that has
been selected in several independent fields through the Lyman Break technique.
Combining those data with archival data, we create a large and homogeneous
sample of $z\sim6$ galaxies ($N=127$), complete in terms of Ly$\alpha$
detection at $>95\%$ for EW(Ly$\alpha)\geq25\AA$. We use this sample to derive
a new measurement of the LAE fraction at $z\sim6$ and derive the physical
properties of these galaxies through spectral energy distribution fitting. We
find a median LAE fraction at $z\sim6$ lower than in previous studies. The main
difference between LAEs and non-LAEs is that the latter are significantly
dustier. Using predictions of our SED fitting code accounting for nebular
emission, we find an effective Ly$\alpha$ escape fraction
$f^{eff}_{esc}(Ly\alpha)=0.23^{+0.36}_{-0.17}$ remarkably consistent with the
value derived by comparing UV luminosity function with Ly$\alpha$ luminosity
function. We conclude that the drop in the LAE fraction from $z\sim6$ to $z>6$
is less dramatic than previously found and the effect of an increasing IGM
neutral fraction is possibly observed at $5<z<6$. Based on our derived
$f^{eff}_{esc}(Ly\alpha)$, we find that the IGM has a relatively small impact
on Ly$\alpha$ photon visibility at $z\sim6$, with a lower limit for the IGM
transmission to \lya\ photons, $T_{IGM}\gtrsim0.20$, likely due to the presence
of outflows. [abdridged]},
added-at = {2017-10-06T10:07:32.000+0200},
author = {De Barros, S. and Pentericci, L. and Vanzella, E. and Castellano, M. and Fontana, A. and Grazian, A. and Conselice, C. J. and Yan, H. and Koekemoer, A. and Cristiani, S. and Dickinson, M. and Finkelstein, S. L. and Maiolino, R.},
biburl = {https://www.bibsonomy.org/bibtex/28c98a80accb548b665e772300054774b/miki},
description = {[1710.01784] A VLT/FORS2 view at $z\sim6$: Lyman-$\alpha$ emitter fraction and galaxy physical properties at the edge of the epoch of cosmic reionization},
interhash = {e7f6711e8f74dc891617cb3ba7b732c2},
intrahash = {8c98a80accb548b665e772300054774b},
keywords = {IGM Lya emitter fraction high-z reionization},
note = {cite arxiv:1710.01784Comment: 13 pages, 13 figures, accepted for publication in A&A},
timestamp = {2017-10-06T10:07:32.000+0200},
title = {A VLT/FORS2 view at $z\sim6$: Lyman-$\alpha$ emitter fraction and galaxy
physical properties at the edge of the epoch of cosmic reionization},
url = {http://arxiv.org/abs/1710.01784},
year = 2017
}