2012/11/29 by Richard S. Ellis, Richard S Ellis, R. J. McLure +25 · 512 citations
Engineering · Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #CCD and CMOS Imaging Sensors #Galaxies: Formation, Evolution, Phenomena #Galaxy #Hubble Deep Field #Hubble Ultra-Deep Field #Luminosity #Luminous infrared galaxy #Photometric redshift #Physics #Redshift #Reionization #Spectral energy distribution #Star formation #astro-ph.CO
paper · pdf · doi:10.1088/2041-8205/763/1/l7
published in The Astrophysical Journal Letters 763(1), L7 (IOP Publishing) · Submitted to Astrophys. J. Lett. on Nov. 7, 2012. Resubmitted after responding to referee report. UDF12 public webpage available at http://udf12.arizona.edu
arxiv created 2012/11/29 · openalex publication_date 2012/12/27 · arxiv updated 2015/06/12 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
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 .