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
- Leiden Observatory, Leiden University, P. O. Box 9513, 2300 RA Leiden (Netherlands)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21208 (United States)
- Universitat Heidelberg, Albert-Ueberle-Straße 2, 69120 Heidelberg (Germany)
- The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)
- Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen (Denmark)
- JPL, California Institute of Technology, MS 169-327, Pasadena, CA 91109 (United States)
- Instituto de Astrofísica de Andalucía, Camino Bajo de Huétor 24, Granada 18008 (Spain)
- Michigan State University, East Lansing, MI 48824 (United States)
- The Carnegie Institute for Science, Carnegie Observatories, Pasadena, CA 91101 (United States)
- INAF, Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
- Academia Sinica, Institute of Astronomy and Astrophysics, P. O. Box 23-141, Taipei 10617, Taiwan (China)
- University of the Basque Country, P. O. Box 644, 48080 Bilbao (Spain)
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 of 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.
- OSTI ID:
- 22370235
- Journal Information:
- Astrophysical Journal, Vol. 795, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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