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Physics and Astronomy


We present the first results and design from the redshift z ∼ 9–10 Brightest of the Reionizing Galaxies Hubble Space Telescope survey BoRG[z9–10], aimed at searching for intrinsically luminous unlensed galaxies during the first 700 Myr after the Big Bang. BoRG[z9–10] is the continuation of a multi-year pure-parallel near-IR and optical imaging campaign with the Wide Field Camera 3. The ongoing survey uses five filters, optimized for detecting the most distant objects and offering continuous wavelength coverage from λ = 0.35 μm to λ = 1.7 μm. We analyze the initial ∼130 arcmin2 of area over 28 independent lines of sight (∼25% of the total planned) to search for z > 7 galaxies using a combination of Lyman-break and photometric redshift selections. From an effective comoving volume of (5–25) × 105 Mpc3 for magnitudes brighter than mAB = 26.5 24.0 – in the H160-band respectively, we find five galaxy candidates at z ~ 8.3–10 detected at high confidence (SN 8 > ), including a source at z ~ 8.4 with mAB = 24.5 (SN 2 ~ 2), which, if confirmed, would be the brightest galaxy identified at such early times (z > 8). In addition, BoRG[z9–10] data yield four galaxies with 7.3 8  z . These new Lyman-break galaxies with m  26.5 are ideal targets for follow-up observations from ground and spacebased observatories to help investigate the complex interplay between dark matter growth, galaxy assembly, and reionization.


© 2016. The American Astronomical Society. All rights reserved.

Original Publication Information

Calvi, V., et al. "Bright Galaxies at Hubble's Redshift Detection Frontier: Preliminary Results and Design from the Redshift z~9-10 BoRG Pure-Parallel HST Survey." 2016. The Astrophysical Journal 817(2): 19 pp.