A selection of Hα emitters at z = 2.1-2.5 using the Ks-band photometry of ZFOURGE

Abstract

Large and less-biased samples of star-forming galaxies are essential to investigate galaxy evolution. H$\alpha$ 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 samples of H$\alpha$ emitters by spectroscopic or narrow-band imaging survey at high-redshifts. In this work, we demonstrate a method to extract H$\alpha$ fluxes of galaxies at $z=2.1$-$2.5$ from $K_s$ broad-band 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$\alpha$ emitters by our method and their fluxes show good agreement with previous measurements in the literature. On the other hand, there are more H$\alpha$ luminous galaxies than previously reported. The discrepancy can be explained by extended H$\alpha$ 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 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$\alpha$ 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 ($>10\mathrm{Myr}$) bursts.

18 pages, 19 figures, Accepted for publication in ApJ

References in corpus (21)

• Cosmic Star Formation History
• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The Cosmic Evolution Survey (COSMOS) -- Overview
• EAZY: A Fast, Public Photometric Redshift Code
• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• 3D-HST+CANDELS: The Evolution of the Galaxy Size-Mass Distribution since $z=3$
• An ultra-deep near-infrared spectrum of a compact quiescent galaxy at z=2.2
• Constraining the Low-Mass Slope of the Star Formation Sequence at 0.5<z<2.5
• H-alpha Observations of a Large Sample of Galaxies at z~2: Implications for Star Formation in High Redshift Galaxies
• What do we learn from IRAC observations of galaxies at 2 < z < 3.5?
• The Relation Between SFR and Stellar Mass for Galaxies at 3.5 $\le z\le$ 6.5 in CANDELS
• The MOSDEF Survey: The Evolution of the Mass-Metallicity Relation from $z=0$ to $z\sim 3.3$
• The FourStar Galaxy Evolution Survey (ZFOURGE): ultraviolet to far-infrared catalogs, medium-bandwidth photometric redshifts with improved accuracy, stellar masses, and confirmation of quiescent galaxies to z~3.5
• HiZELS: a high redshift survey of H-alpha emitters. I: the cosmic star-formation rate and clustering at z=2.23
• High-precision Photometric Redshifts from Spitzer/IRAC: Extreme [3.6]-[4.5] Colors Identify Galaxies in the Redshift Range z~6.6-6.9
• The KMOS^3D Survey: data release and final survey paper
• Exploring the z=3-4 massive galaxy population with ZFOURGE: the prevalence of dusty and quiescent galaxies
• ZFIRE: A KECK/MOSFIRE Spectroscopic Survey of Galaxies in Rich Environments at z~2
• Star Formation Stochasticity Measured from the Distribution of Burst Indicators
• Broad-band selection, spectroscopic identification, and physical properties of a population of extreme emission line galaxies at 3<z<3.7
• Extended star-forming region within galaxies in a dense proto-cluster core at z=2.53

Cited by in corpus (6)

• An Hα view of galaxy build-up in the first 2 Gyr: luminosity functions at z~4-6.5 from NIRCam/grism spectroscopy
• The JWST Emission Line Survey (JELS): Extending rest-optical narrow-band emission line selection into the Epoch of Reionization
• Towards unveiling the Cosmic Reionization: the ionizing photon production efficiency (${\xi }_{ion}$) of Low-mass H$\alpha$ emitters at $z\sim 2.3$
• Multiple emission lines of H$\alpha$ emitters at $z\sim 2.3$ from the broad and medium-band photometry in the ZFOURGE Survey
• The JWST Emission Line Survey (JELS): The sizes and merger fraction of star-forming galaxies during the Epoch of Reionization
• Compact [OIII] emission-line regions ("Green Seeds") in $\mathrm{H}\alpha$ emitters at Cosmic Noon from JWST Observations