2008/02/29 by L. D. Bradley, L. D. Bradley, R. J. Bouwens +20 · 132 citations
Physics and Astronomy · #Abell 2744 #Astronomy and Astrophysical Research #Brightest cluster galaxy #Cluster (spacecraft) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Galaxy merger #Gamma-ray bursts and supernovae #Interacting galaxy #Type-cD galaxy #astro-ph
paper · pdf · doi:10.1086/533519
published in The Astrophysical Journal 678(2), 647-654 (IOP Publishing) · Accepted for publication in the Astrophysical Journal, 8 pages, 8 figures, updated to match version in press
openalex publication_date 2008/04/30 · arxiv created 2008/05/13 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Using Hubble Space Telescope ( HST ) and Spitzer IRAC imaging, we report the discovery of a very bright strongly lensed Lyman break galaxy (LBG) candidate at z ∼ 7.6 in the field of the massive galaxy cluster Abell 1689 ( z = 0.18). The galaxy candidate, which we refer to as A1689-zD1, shows a strong z 850 − J 110 break of at least 2.2 mag and is completely undetected (<1 σ) in HST Advanced Camera for Surveys (ACS) g 475 , r 625 , i 775 , and z 850 data. These properties, combined with the very blue J 110 − H 160 and H 160 − [ 4.5 μ m ] colors, are exactly the properties of an z ∼ 7.6 LBG, and can only be reasonably fit by a star-forming galaxy at z = 7.6 ± 0.4 (χ 2 ν = 1.1). Attempts to reproduce these properties with a model galaxy at z < 4 yield particularly poor fits (χ 2 ν ⩾ 25). A1689-zD1 has an observed (lensed) magnitude of 24.7 AB (8 σ) in the NICMOS H 160 band and is ~1.3 mag brighter than the brightest known z 850 -dropout galaxy. When corrected for the cluster magnification of ~9.3 at z ∼ 7.6, the candidate has an intrinsic magnitude of H 160 = 27.1 AB, or about an L * galaxy at z ∼ 7.6. The source-plane deprojection shows that the star formation is occurring in compact knots of size ≲300 pc. The best-fit stellar population synthesis models yield a median redshift of 7.6, stellar masses (1.6–3.9) × 10 9 M ☉ , stellar ages 45-320 Myr, star formation rates ≲7.6 M ☉ yr −1 , and low reddening with A V ⩽ 0.3. These properties are generally similar to those of LBGs found at z ∼ 5–6. The inferred stellar ages suggest a formation redshift of z ∼ 8–10 ( t ≲ 0.63 Gyr). A1689-zD1 is the brightest observed, highly reliable z > 7.0 galaxy candidate found to date.