TY - JOUR
T1 - The Lyman Continuum Escape Fraction of Emission Line-selected z ∼ 2.5 Galaxies Is Less Than 15%
AU - Rutkowski, Michael J.
AU - Scarlata, Claudia
AU - Henry, Alaina
AU - Hayes, Matthew
AU - Mehta, Vihang
AU - Hathi, Nimish
AU - Cohen, Seth
AU - Windhorst, Rogier
AU - Koekemoer, Anton M.
AU - Teplitz, Harry I.
AU - Haardt, Francesco
AU - Siana, Brian
N1 - Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.
PY - 2017/6/1
Y1 - 2017/6/1
N2 - Recent work suggests that strong emission line, star-forming galaxies (SFGs) may be significant Lyman continuum leakers. We combine archival Hubble Space Telescope broadband ultraviolet and optical imaging (F275W and F606W, respectively) with emission line catalogs derived from WFC3 IR G141 grism spectroscopy to search for escaping Lyman continuum (LyC) emission from homogeneously selected z ∼ 2.5 SFGs. We detect no escaping Lyman continuum from SFGs selected on [O ii] nebular emission (N = 208) and, within a narrow redshift range, on [O iii]/[O ii]. We measure 1σ upper limits to the LyC escape fraction relative to the non-ionizing UV continuum from [O ii] emitters, f esc ≲ 5.6%, and strong [O iii]/[O ii] > 5 ELGs, f esc ≲ 14.0%. Our observations are not deep enough to detect f esc ∼ 10% typical of low-redshift Lyman continuum emitters. However, we find that this population represents a small fraction of the star-forming galaxy population at z ∼ 2. Thus, unless the number of extreme emission line galaxies grows substantially to z 6, such galaxies may be insufficient for reionization. Deeper survey data in the rest-frame ionizing UV will be necessary to determine whether strong line ratios could be useful for pre-selecting LyC leakers at high redshift.
AB - Recent work suggests that strong emission line, star-forming galaxies (SFGs) may be significant Lyman continuum leakers. We combine archival Hubble Space Telescope broadband ultraviolet and optical imaging (F275W and F606W, respectively) with emission line catalogs derived from WFC3 IR G141 grism spectroscopy to search for escaping Lyman continuum (LyC) emission from homogeneously selected z ∼ 2.5 SFGs. We detect no escaping Lyman continuum from SFGs selected on [O ii] nebular emission (N = 208) and, within a narrow redshift range, on [O iii]/[O ii]. We measure 1σ upper limits to the LyC escape fraction relative to the non-ionizing UV continuum from [O ii] emitters, f esc ≲ 5.6%, and strong [O iii]/[O ii] > 5 ELGs, f esc ≲ 14.0%. Our observations are not deep enough to detect f esc ∼ 10% typical of low-redshift Lyman continuum emitters. However, we find that this population represents a small fraction of the star-forming galaxy population at z ∼ 2. Thus, unless the number of extreme emission line galaxies grows substantially to z 6, such galaxies may be insufficient for reionization. Deeper survey data in the rest-frame ionizing UV will be necessary to determine whether strong line ratios could be useful for pre-selecting LyC leakers at high redshift.
KW - galaxies: general
KW - galaxies: star formation
KW - ultraviolet: galaxies
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U2 - 10.3847/2041-8213/aa733b
DO - 10.3847/2041-8213/aa733b
M3 - Article
AN - SCOPUS:85020274255
SN - 2041-8205
VL - 841
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L27
ER -