To date no direct detection of Lyman continuum emission has been measured for
intermediate--redshift z~1 star-forming galaxies . We combine HST grism
spectroscopy with GALEX UV and ground--based optical imaging to extend the
search for escaping Lyman continuum to a large (~600) sample of z~1 low-mass,
moderately star-forming galaxies selected initially on H$\alpha$ emission. The
characteristic escape fraction of LyC from SFGs that populate this parameter
space remains weakly constrained by previous surveys, but these faint SFGs are
assumed to play a significant role in the reionization of neutral hydrogen in
the intergalactic medium (IGM) at high redshift (z>6). We do not make an
unambiguous detection of escaping LyC radiation from this $z\sim1$ sample,
individual non--detections to constrain the absolute Lyman continuum escape
fraction, $f_esc$<2.1% (3$\sigma$). We measure upper limits of $f_esc$<9.6%
from a sample of SFGs selected on high H$\alpha$ equivalent width (EW>200\AA),
which are thought to be close analogs of high redshift sources of reionization.
For reference, we also present an emissivity--weighted escape fraction which is
useful as a measurement of the general contribution of the SFGs to the z~1
ionizing UV background. In the discussion, we consider the implications of
these intermediate redshift constraints for the re--ionization of hydrogen in
the intergalactic medium at high (z>6) redshift. If the escape fraction of SFGs
increases with redshift or an unobserved population of faint (M$_UV$<-13 AB)
SFGs with $f_esc$>3% contributes significantly, reionization by SFGs is
marginally consistent with independent observations from Planck.
Description
[1511.01998] The Lyman Continuum Escape Fraction of Low-Mass Star-Forming Galaxies at z~1
%0 Generic
%1 rutkowski2015lyman
%A Rutkowski, Michael J.
%A Scarlata, Claudia
%A Haardt, Francesco
%A Siana, Brian
%A Henry, Alaina
%A Rafelski, Marc
%A Hayes, Matthew
%A Salvato, Mara
%A Pahl, Anthony J.
%A Mehta, Vihang
%A Beck, Melanie
%A Malkan, Matthew
%A Teplitz, Harry I.
%D 2015
%K escape fraction low mass z~1
%T The Lyman Continuum Escape Fraction of Low-Mass Star-Forming Galaxies at
z~1
%U http://arxiv.org/abs/1511.01998
%X To date no direct detection of Lyman continuum emission has been measured for
intermediate--redshift z~1 star-forming galaxies . We combine HST grism
spectroscopy with GALEX UV and ground--based optical imaging to extend the
search for escaping Lyman continuum to a large (~600) sample of z~1 low-mass,
moderately star-forming galaxies selected initially on H$\alpha$ emission. The
characteristic escape fraction of LyC from SFGs that populate this parameter
space remains weakly constrained by previous surveys, but these faint SFGs are
assumed to play a significant role in the reionization of neutral hydrogen in
the intergalactic medium (IGM) at high redshift (z>6). We do not make an
unambiguous detection of escaping LyC radiation from this $z\sim1$ sample,
individual non--detections to constrain the absolute Lyman continuum escape
fraction, $f_esc$<2.1% (3$\sigma$). We measure upper limits of $f_esc$<9.6%
from a sample of SFGs selected on high H$\alpha$ equivalent width (EW>200\AA),
which are thought to be close analogs of high redshift sources of reionization.
For reference, we also present an emissivity--weighted escape fraction which is
useful as a measurement of the general contribution of the SFGs to the z~1
ionizing UV background. In the discussion, we consider the implications of
these intermediate redshift constraints for the re--ionization of hydrogen in
the intergalactic medium at high (z>6) redshift. If the escape fraction of SFGs
increases with redshift or an unobserved population of faint (M$_UV$<-13 AB)
SFGs with $f_esc$>3% contributes significantly, reionization by SFGs is
marginally consistent with independent observations from Planck.
@misc{rutkowski2015lyman,
abstract = {To date no direct detection of Lyman continuum emission has been measured for
intermediate--redshift z~1 star-forming galaxies . We combine HST grism
spectroscopy with GALEX UV and ground--based optical imaging to extend the
search for escaping Lyman continuum to a large (~600) sample of z~1 low-mass,
moderately star-forming galaxies selected initially on H$\alpha$ emission. The
characteristic escape fraction of LyC from SFGs that populate this parameter
space remains weakly constrained by previous surveys, but these faint SFGs are
assumed to play a significant role in the reionization of neutral hydrogen in
the intergalactic medium (IGM) at high redshift (z>6). We do not make an
unambiguous detection of escaping LyC radiation from this $z\sim1$ sample,
individual non--detections to constrain the absolute Lyman continuum escape
fraction, $f_{esc}$<2.1% (3$\sigma$). We measure upper limits of $f_{esc}$<9.6%
from a sample of SFGs selected on high H$\alpha$ equivalent width (EW>200\AA),
which are thought to be close analogs of high redshift sources of reionization.
For reference, we also present an emissivity--weighted escape fraction which is
useful as a measurement of the general contribution of the SFGs to the z~1
ionizing UV background. In the discussion, we consider the implications of
these intermediate redshift constraints for the re--ionization of hydrogen in
the intergalactic medium at high (z>6) redshift. If the escape fraction of SFGs
increases with redshift or an unobserved population of faint (M$_{UV}$<-13 AB)
SFGs with $f_{esc}$>3% contributes significantly, reionization by SFGs is
marginally consistent with independent observations from Planck.},
added-at = {2015-11-09T10:24:13.000+0100},
author = {Rutkowski, Michael J. and Scarlata, Claudia and Haardt, Francesco and Siana, Brian and Henry, Alaina and Rafelski, Marc and Hayes, Matthew and Salvato, Mara and Pahl, Anthony J. and Mehta, Vihang and Beck, Melanie and Malkan, Matthew and Teplitz, Harry I.},
biburl = {https://www.bibsonomy.org/bibtex/2b4fceb355c6964920a4dabe779e7f233/miki},
description = {[1511.01998] The Lyman Continuum Escape Fraction of Low-Mass Star-Forming Galaxies at z~1},
interhash = {a78992632ac5f5c8d9b9f056b926dbb4},
intrahash = {b4fceb355c6964920a4dabe779e7f233},
keywords = {escape fraction low mass z~1},
note = {cite arxiv:1511.01998Comment: submitted for second review to ApJ},
timestamp = {2015-11-09T10:24:13.000+0100},
title = {The Lyman Continuum Escape Fraction of Low-Mass Star-Forming Galaxies at
z~1},
url = {http://arxiv.org/abs/1511.01998},
year = 2015
}