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arXiv · 1805.05038

HST followup observations of two bright z ~ 8 candidate galaxies from the BoRG pure-parallel survey

R. C. Livermore·M. Trenti·L. D. Bradley·S. R. Bernard·B. W. Holwerda·C. A. Mason·T. Treu
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Abstract

We present followup imaging of two bright (L > L*) galaxy candidates at z > 8 from the Brightest of Reionizing Galaxies (BoRG) survey with the F098M filter on HST/WFC3. The F098M filter provides an additional constraint on the flux blueward of the spectral break, and the observations are designed to discriminate between low- and high-z photometric redshift solutions for these galaxies. Our results confirm one galaxy, BoRG 0116+1425 747, as a highly probable z ~ 8 source, but reveal that BoRG 0116+1425 630 - previously the brightest known z > 8 candidate (mAB = 24.5) - is likely to be a z ~ 2 interloper. As this source was substantially brighter than any other z > 8 candidate, removing it from the sample has a significant impact on the derived UV luminosity function in this epoch. We show that while previous BoRG results favored a shallow power-law decline in the bright end of the luminosity function prior to reionization, there is now no evidence for departure from a Schechter function form and therefore no evidence for a difference in galaxy formation processes before and after reionization.

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R. C. Livermore, M. Trenti, L. D. Bradley, S. R. Bernard, B. W. Holwerda, C. A. Mason, T. Treu. 2018-07-04. HST followup observations of two bright z ~ 8 candidate galaxies from the BoRG pure-parallel survey. https://doi.org/10.3847/2041-8213%2Faacd16

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