Publication
A Selection of Hα Emitters at z = 2.1–2.5 Using the K
s
-band Photometry of ZFOURGE
Publisher:
American Astronomical Society
Date:
12-2022
DOI:
10.3847/1538-4357/AC9FCE
Abstract: Large and less-biased s les of star-forming galaxies are essential to investigate galaxy evolution. H α emission line is one of the most reliable tracers of star-forming galaxies because its strength is directly related to recent star formation. However, it is observationally expensive to construct large s les of H α emitters by spectroscopic or narrowband imaging survey at high redshifts. In this work, we demonstrate a method to extract H α fluxes of galaxies at z = 2.1–2.5 from K s broadband photometry of ZFOURGE catalog. Combined with 25–39 other filters, we estimate the emission-line fluxes by SED fitting with stellar population models that incorporate emission-line strengths. 2005 galaxies are selected as H α emitters by our method and their fluxes show good agreement with previous measurements in the literature. On the other hand, there are more H α luminous galaxies than previously reported. The discrepancy can be explained by extended H α profiles of massive galaxies and a luminosity dependence of dust attenuation, which are not taken into account in the previous work. We also find that there are a large number of low-mass galaxies with a much higher specific star formation rate (sSFR) than expected from the extrapolated star formation main sequence. Such low-mass galaxies exhibit larger ratios between H α and UV fluxes compared to more massive high sSFR galaxies. This result implies that a “starburst” mode may differ among galaxies: low-mass galaxies appear to assemble their stellar mass via short-duration bursts, while more massive galaxies tend to experience longer-duration ( Myr) bursts.