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Title: The properties of Hα emission-line galaxies at z = 2.24

Using deep narrowband H {sub 2} S1 and K {sub s}-band imaging data obtained with CFHT/WIRCam, we identify a sample of 56 Hα emission-line galaxies (ELGs) at z = 2.24 with the 5σ depths of H {sub 2} S1 = 22.8 and K {sub s} = 24.8 (AB) over a 383 arcmin{sup 2} area in the Extended Chandra Deep Field South. A detailed analysis is carried out with existing multi-wavelength data in this field. Three of the 56 Hα ELGs are detected in Chandra 4 Ms X-ray observations and two of them are classified as active galactic nuclei. The rest-frame UV and optical morphologies revealed by HST/ACS and WFC3 deep images show that nearly half of the Hα ELGs are either merging systems or have a close companion, indicating that the merging/interacting processes play a key role in regulating star formation at cosmic epoch z = 2-3. About 14% are too faint to be resolved in the rest-frame UV morphology due to high dust extinction. We estimate dust extinction from spectral energy distributions. We find that dust extinction is generally correlated with Hα luminosity and stellar mass. Our results suggest that Hα ELGs are representative of star-forming galaxies. Applying extinctionmore » corrections to individual objects, we examine the intrinsic Hα luminosity function (LF) at z = 2.24, obtaining a best-fit Schechter function characterized by a faint-end slope of α = – 1.3. This is shallower than the typical slope of α ≅ –1.6 in previous works based on constant extinction correction. We demonstrate that this difference is mainly due to the different extinction corrections. The proper extinction correction is thus the key to recovering the intrinsic LF as the extinction globally increases with Hα luminosity. Moreover, we find that our Hα LF mirrors the stellar mass function of star-forming galaxies at the same cosmic epoch. This finding indeed reflects the tight correlation between star formation rate and stellar mass for star-forming galaxies, i.e., the so-called main sequence.« less
Authors:
;  [1] ;  [2] ;  [3] ; ; ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9]
  1. Purple Mountain Observatory, China Academy of Sciences, West Beijing Road 2, Nanjing 210008 (China)
  2. Academia Sinica Institute of Astronomy and Astrophysics, Taipei 10617, Taiwan (China)
  3. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  4. CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei 230026 (China)
  5. Institute for Astronomy and History of Science and Technology, Dali University, Yunnan 671003 (China)
  6. School of Astronomy and Space Science, Nanjing University, 22 Hankou RD, Nanjing 210093 (China)
  7. National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)
  8. Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 2000 30 (China)
  9. Tianjin Astrophysics Center, Tianjin Normal University, Tianjin 300387 (China)
Publication Date:
OSTI Identifier:
22357220
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 784; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CORRECTIONS; CORRELATIONS; DUSTS; EMISSION; EVOLUTION; GALAXIES; GALAXY NUCLEI; IMAGES; LUMINOSITY; MASS; RED SHIFT; STARS; WAVELENGTHS; X RADIATION