Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published January 20, 2013 | Published
Journal Article Open

The Abundance of Star-forming Galaxies in the Redshift Range 8.5-12: New Results from the 2012 Hubble Ultra Deep Field Campaign

Abstract

We present the results of the deepest search to date for star-forming galaxies beyond a redshift z ≃ 8.5 utilizing a new sequence of near-infrared Wide-Field Camera 3 (WFC3/IR) images of the Hubble Ultra Deep Field (UDF). This "UDF12" campaign completed in 2012 September doubles the earlier exposures with WFC3/IR in this field and quadruples the exposure in the key F105W filter used to locate such distant galaxies. Combined with additional imaging in the F140W filter, the fidelity of high-redshift candidates is greatly improved. Using spectral energy distribution fitting techniques on objects selected from a deep multi-band near-infrared stack, we find seven promising z > 8.5 candidates. As none of the previously claimed UDF candidates with 8.5 < z < 10 are confirmed by our deeper multi-band imaging, our campaign has transformed the measured abundance of galaxies in this redshift range. Although we recover the candidate UDFj-39546284 (previously proposed at z = 10.3), it is undetected in the newly added F140W image, implying that it lies at z = 11.9 or is an intense emission line galaxy at z ≃ 2.4. Although no physically plausible model can explain the required line intensity given the lack of Lyα or broadband UV signal, without an infrared spectrum we cannot rule out an exotic interloper. Regardless, our robust z ≃ 8.5-10 sample demonstrates a luminosity density that continues the smooth decline observed over 6 < z < 8. Such continuity has important implications for models of cosmic reionization and future searches for z >10 galaxies with James Webb Space Telescope.

Additional Information

© 2013 American Astronomical Society. Received 2012 November 6; accepted 2012 December 5; published 2012 December 27. The U.S. authors acknowledge financial support from the Space Telescope Science Institute under award HST-GO- 12498.01-A. J.S.D. acknowledges support of the European Research Council and the Royal Society. R.J.M. acknowledges funding from the Leverhulme Trust. We thank Kimihiko Nakajima for assistance with the Keck spectroscopy. This work is based on data from the Hubble Space Telescope operated by NASA through the Space Telescope Science Institute via the association of Universities for Research in Astronomy, Inc. under contract NAS5-26555.

Attached Files

Published - 2041-8205_763_1_L7.pdf

Files

2041-8205_763_1_L7.pdf
Files (817.2 kB)
Name Size Download all
md5:0aa348a0c3db3a476d3f6fd3f31af7e5
817.2 kB Preview Download

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023