2020ApJ...895..116E


Query : 2020ApJ...895..116E

2020ApJ...895..116E - Astrophys. J., 895, 116-116 (2020/June-1)

The ionizing photon production efficiency (ξion) of lensed dwarf galaxies at z ∼ 2.

EMAMI N., SIANA B., ALAVI A., GBUREK T., FREEMAN W.R., RICHARD J., WEISZ D.R. and STARK D.P.

Abstract (from CDS):

We measure the ionizing photon production efficiency (ξion) of low-mass galaxies (107.8-109.8 M) at 1.4 < z < 2.7 to better understand the contribution of dwarf galaxies to the ionizing background and reionization. We target galaxies that are magnified by strong-lensing galaxy clusters and use Keck/MOSFIRE to measure nebular emission-line fluxes and Hubble Space Telescope to measure the rest-UV and rest-optical photometry. We present two methods of stacking. First, we take the average of the log of Hα-to-UV luminosity ratios (L/LUV) of galaxies to determine the standard log(ξion). Second, we take the logarithm of the total L over the total LUV. We prefer the latter, as it provides the total ionizing UV luminosity density of galaxies when multiplied by the nonionizing UV luminosity density. log(ξion) calculated from the second method is ∼0.2 dex higher than the first method. We do not find any strong dependence between log(ξion) and stellar mass, far-UV magnitude (MUV), or UV spectral slope (β). We report a value of log(ξion) ∼ 25.47 ± 0.09 for our UV-complete sample (-22< MUV< -17.3) and ∼25.37 ± 0.11 for our mass-complete sample (7.8 < log(M*) < 9.8). These values are consistent with measurements of more massive, more luminous galaxies in other high-redshift studies that use the same stacking technique. Our log(ξion) is 0.2-0.3 dex higher than low-redshift galaxies of similar mass, indicating an evolution in the stellar properties, possibly due to metallicity or age. We also find a correlation between log(ξion) and the equivalent widths of Hα and [O III] λ5007 fluxes, confirming that these equivalent widths can be used to estimate ξion.

Abstract Copyright: © 2020. The American Astronomical Society. All rights reserved.

Journal keyword(s): Dwarf galaxies - Galaxy evolution - High-redshift galaxies

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 ClG J0717+3745 ClG 07 17 36.50 +37 45 23.0           ~ 459 0
2 MCS J1149.5+2223 ClG 11 49 35.8 +22 23 55           ~ 451 0
3 ACO 1689 ClG 13 11 29.5 -01 20 28           ~ 1116 0

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