Lyman Continuum Galaxy Candidates in COSMOS. (arXiv:2110.06945v3 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Prichard_L/0/1/0/all/0/1">Laura J. Prichard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rafelski_M/0/1/0/all/0/1">Marc Rafelski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cooke_J/0/1/0/all/0/1">Jeff Cooke</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mestric_U/0/1/0/all/0/1">Uros Mestric</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bassett_R/0/1/0/all/0/1">Robert Bassett</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ryan_Weber_E/0/1/0/all/0/1">Emma V. Ryan-Weber</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sunnquist_B/0/1/0/all/0/1">Ben Sunnquist</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alavi_A/0/1/0/all/0/1">Anahita Alavi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hathi_N/0/1/0/all/0/1">Nimish Hathi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_X/0/1/0/all/0/1">Xin Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Revalski_M/0/1/0/all/0/1">Mitchell Revalski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bajaj_V/0/1/0/all/0/1">Varun Bajaj</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+OMeara_J/0/1/0/all/0/1">John M. O'Meara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Spitler_L/0/1/0/all/0/1">Lee Spitler</a>
Star-forming galaxies are the sources likely to have reionized the universe.
As we cannot observe them directly due to the opacity of the intergalactic
medium at $zgtrsim5$, we study $zsim3text{–}5$ galaxies as proxies to place
observational constraints on cosmic reionization. Using new deep textit{Hubble
Space Telescope} rest-frame UV F336W and F435W imaging (30-orbit,
$sim40$~arcmin$^2$, $sim29text{–}30$~mag depth at 5$sigma$), we attempt to
identify a sample of Lyman continuum galaxies (LCGs). These are individual
sources that emit ionizing flux below the Lyman break ($<912~text{AA}$). This
population would allow us to constrain cosmic reionization parameters such as
the number density and escape fraction ($f_{rm esc}$) of ionizing sources. We
compile a comprehensive parent sample that does not rely on the Lyman-break
technique for redshifts. We present three new spectroscopic candidates at
$zsim3.7text{–}4.4$, and 32 new photometric candidates. The high-resolution
multi-band HST imaging and new Keck/Low Resolution Imaging Spectrometer (LRIS)
redshifts make these promising spectroscopic LCG candidates. Using both a
traditional and probabilistic approach, we find the most likely $f_{rm esc}$
values for the three spectroscopic LCG candidates are $>100%$, and therefore
not physical. We are unable to confirm the true nature of these sources with
the best available imaging and direct blue Keck/LRIS spectroscopy. More
spectra, especially from the new class of 30 m telescopes, will be required to
build a statistical sample of LCGs to place firm observational constraints on
cosmic reionization.
Star-forming galaxies are the sources likely to have reionized the universe.
As we cannot observe them directly due to the opacity of the intergalactic
medium at $zgtrsim5$, we study $zsim3text{–}5$ galaxies as proxies to place
observational constraints on cosmic reionization. Using new deep textit{Hubble
Space Telescope} rest-frame UV F336W and F435W imaging (30-orbit,
$sim40$~arcmin$^2$, $sim29text{–}30$~mag depth at 5$sigma$), we attempt to
identify a sample of Lyman continuum galaxies (LCGs). These are individual
sources that emit ionizing flux below the Lyman break ($<912~text{AA}$). This
population would allow us to constrain cosmic reionization parameters such as
the number density and escape fraction ($f_{rm esc}$) of ionizing sources. We
compile a comprehensive parent sample that does not rely on the Lyman-break
technique for redshifts. We present three new spectroscopic candidates at
$zsim3.7text{–}4.4$, and 32 new photometric candidates. The high-resolution
multi-band HST imaging and new Keck/Low Resolution Imaging Spectrometer (LRIS)
redshifts make these promising spectroscopic LCG candidates. Using both a
traditional and probabilistic approach, we find the most likely $f_{rm esc}$
values for the three spectroscopic LCG candidates are $>100%$, and therefore
not physical. We are unable to confirm the true nature of these sources with
the best available imaging and direct blue Keck/LRIS spectroscopy. More
spectra, especially from the new class of 30 m telescopes, will be required to
build a statistical sample of LCGs to place firm observational constraints on
cosmic reionization.
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