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Title: A census of star-forming galaxies in the z ∼ 9-10 universe based on HST+Spitzer observations over 19 clash clusters: three candidate z ∼ 9-10 galaxies and improved constraints on the star formation rate density at z ∼ 9.2

We utilize a two-color Lyman-break selection criterion to search for z ∼ 9-10 galaxies over the first 19 clusters in the CLASH program. A systematic search yields three z ∼ 9-10 candidates. While we have already reported the most robust of these candidates, MACS1149-JD, two additional z ∼ 9 candidates are also found and have H {sub 160}-band magnitudes of ∼26.2-26.9. A careful assessment of various sources of contamination suggests ≲1 contaminants for our z ∼ 9-10 selection. To determine the implications of these search results for the luminosity function (LF) and star formation rate density at z ∼ 9, we introduce a new differential approach to deriving these quantities in lensing fields. Our procedure is to derive the evolution by comparing the number of z ∼ 9-10 galaxy candidates found in CLASH with the number of galaxies in a slightly lower-redshift sample (after correcting for the differences in selection volumes), here taken to be z ∼ 8. This procedure takes advantage of the fact that the relative volumes available for the z ∼ 8 and z ∼ 9-10 selections behind lensing clusters are not greatly dependent on the details of the lensing models. We find that the normalization ofmore » the UV LF at z ∼ 9 is just 0.28{sub −0.20}{sup +0.39}× that at z ∼ 8, which is ∼1.4{sub −0.8}{sup +3.0}× lower than extrapolating z ∼ 4-8 LF results. While consistent with the evolution in the UV LF seen at z ∼ 4-8, these results marginally favor a more rapid evolution at z > 8. Compared to similar evolutionary findings from the HUDF, our result is less insensitive to large-scale structure uncertainties, given our many independent sightlines on the high-redshift universe.« less
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  1. Leiden Observatory, Leiden University, P. O. Box 9513, 2300 RA Leiden (Netherlands)
  2. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21208 (United States)
  3. Universitat Heidelberg, Albert-Ueberle-Straße 2, 69120 Heidelberg (Germany)
  4. The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)
  5. Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen (Denmark)
  6. JPL, California Institute of Technology, MS 169-327, Pasadena, CA 91109 (United States)
  7. Instituto de Astrofísica de Andalucía, Camino Bajo de Huétor 24, Granada 18008 (Spain)
  8. Michigan State University, East Lansing, MI 48824 (United States)
  9. The Carnegie Institute for Science, Carnegie Observatories, Pasadena, CA 91101 (United States)
  10. INAF, Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
  11. Academia Sinica, Institute of Astronomy and Astrophysics, P. O. Box 23-141, Taipei 10617, Taiwan (China)
  12. University of the Basque Country, P. O. Box 644, 48080 Bilbao (Spain)
Publication Date:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 795; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States