PROBING THE DAWN OF GALAXIES AT z {approx} 9-12: NEW CONSTRAINTS FROM HUDF12/XDF AND CANDELS DATA
- UCO/Lick Observatory, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States)
- Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands)
- Department of Astronomy, Yale University, New Haven, CT 06520 (United States)
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
We present a comprehensive analysis of z > 8 galaxies based on ultra-deep WFC3/IR data. We exploit all the WFC3/IR imaging over the Hubble Ultra-Deep Field from the HUDF09 and the new HUDF12 program, in addition to the HUDF09 parallel field data, as well as wider area imaging over GOODS-South. Galaxies are selected based on the Lyman break technique in three samples centered around z {approx} 9, z {approx} 10, and z {approx} 11, with seven z {approx} 9 galaxy candidates, and one each at z {approx} 10 and z {approx} 11. We confirm a new z {approx} 10 candidate (with z = 9.8 {+-} 0.6) that was not convincingly identified in our first z {approx} 10 sample. Using these candidates, we perform one of the first estimates of the z {approx} 9 UV luminosity function (LF) and improve our previous constraints at z {approx} 10. Extrapolating the lower redshift UV LF evolution should have revealed 17 z {approx} 9 and 9 z {approx} 10 sources, i.e., a factor {approx}3 Multiplication-Sign and 9 Multiplication-Sign larger than observed. The inferred star formation rate density (SFRD) in galaxies above 0.7 M{sub Sun} yr{sup -1} decreases by 0.6 {+-} 0.2 dex from z {approx} 8 to z {approx} 9, in excellent agreement with previous estimates. From a combination of all current measurements, we find a best estimate of a factor 10 Multiplication-Sign decrease in the SFRD from z {approx} 8 to z {approx} 10, following (1 + z){sup -11.4{+-}3.1}. Our measurements thus confirm our previous finding of an accelerated evolution beyond z {approx} 8, and signify a very rapid build-up of galaxies with M{sub UV} < -17.7 mag within only {approx}200 Myr from z {approx} 10 to z {approx} 8, in the heart of cosmic reionization.
- OSTI ID:
- 22131050
- Journal Information:
- Astrophysical Journal, Vol. 773, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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