High Equivalent Width of H alpha plus [N II] Emission in z similar to 8 Lyman-break Galaxies from IRAC 5.8 mu m Observations: Evidence for Efficient Lyman-continuum Photon Production in the Epoch of Reionization
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High Equivalent Width of H alpha plus [N II] Emission in z similar to 8 Lyman-break Galaxies from IRAC 5.8 mu m Observations : Evidence for Efficient Lyman-continuum Photon Production in the Epoch of Reionization. / Stefanon, Mauro; Bouwens, Rychard J.; Illingworth, Garth D.; Labbe, Ivo; Oesch, Pascal A.; Gonzalez, Valentino.
In: Astrophysical Journal, Vol. 935, No. 2, 94, 01.08.2022.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - High Equivalent Width of H alpha plus [N II] Emission in z similar to 8 Lyman-break Galaxies from IRAC 5.8 mu m Observations
T2 - Evidence for Efficient Lyman-continuum Photon Production in the Epoch of Reionization
AU - Stefanon, Mauro
AU - Bouwens, Rychard J.
AU - Illingworth, Garth D.
AU - Labbe, Ivo
AU - Oesch, Pascal A.
AU - Gonzalez, Valentino
PY - 2022/8/1
Y1 - 2022/8/1
N2 - We measure, for the first time, the median equivalent width (EW) of H alpha+[N II] in star-forming galaxies at z similar to 8. Our estimate leverages the unique photometric depth of the Spitzer/IRAC 5.8 mu m band mosaics (probing approximate to 5500-7100 angstrom at z similar to 8) of the GOODS Reionization Era Wide Area Treasury from Spitzer (GREATS) program. We median-stacked the stamps of 102 Lyman-break galaxies in the 3.6, 4.5, 5.8, and 8.0 mu m bands, after carefully removing potential contamination from neighboring sources. We infer an extreme rest-frame EW0(H alpha+[N II]) = 2328(-1127)(+1326) angstrom from the measured red [3.6] - [5.8] = 0.82 +/- 0.27 mag, consistent with young (less than or similar to 10(7) yr) average stellar population ages at z similar to 8. This implies an ionizing photon production efficiency of log(xi(ion,0)/erg Hz(-1)) = 25.97(-0.28)(+0.18). Such a high value for photoproduction, similar to the highest values found at z less than or similar to 4, indicates that only modest escape fractions f(esc) less than or similar to 0.3 (at 2 sigma) are sufficient for galaxies brighter than M-UV < -18 mag to reionize the neutral hydrogen at z similar to 8. This requirement is relaxed even more to f(esc)
AB - We measure, for the first time, the median equivalent width (EW) of H alpha+[N II] in star-forming galaxies at z similar to 8. Our estimate leverages the unique photometric depth of the Spitzer/IRAC 5.8 mu m band mosaics (probing approximate to 5500-7100 angstrom at z similar to 8) of the GOODS Reionization Era Wide Area Treasury from Spitzer (GREATS) program. We median-stacked the stamps of 102 Lyman-break galaxies in the 3.6, 4.5, 5.8, and 8.0 mu m bands, after carefully removing potential contamination from neighboring sources. We infer an extreme rest-frame EW0(H alpha+[N II]) = 2328(-1127)(+1326) angstrom from the measured red [3.6] - [5.8] = 0.82 +/- 0.27 mag, consistent with young (less than or similar to 10(7) yr) average stellar population ages at z similar to 8. This implies an ionizing photon production efficiency of log(xi(ion,0)/erg Hz(-1)) = 25.97(-0.28)(+0.18). Such a high value for photoproduction, similar to the highest values found at z less than or similar to 4, indicates that only modest escape fractions f(esc) less than or similar to 0.3 (at 2 sigma) are sufficient for galaxies brighter than M-UV < -18 mag to reionize the neutral hydrogen at z similar to 8. This requirement is relaxed even more to f(esc)
KW - STAR-FORMING GALAXIES
KW - UV LUMINOSITY FUNCTIONS
KW - ULTRA DEEP FIELD
KW - YOUNG STELLAR POPULATIONS
KW - LY-ALPHA
KW - ESCAPE FRACTION
KW - ACCELERATED REIONIZATION
KW - SIGNIFICANT EVOLUTION
KW - PHYSICAL-PROPERTIES
KW - DUST ATTENUATION
U2 - 10.3847/1538-4357/ac7e44
DO - 10.3847/1538-4357/ac7e44
M3 - Journal article
VL - 935
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 94
ER -
ID: 317936243