2012/07/20 by Maruša Bradač, Eros Vanzella, Nicholas Hall +7 · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Galaxies: Formation, Evolution, Phenomena #Gamma-ray bursts and supernovae #astro-ph.CO
paper · pdf · doi:10.1088/2041-8205/755/1/l7
published as The Astrophysical Journal Letters, Volume 755, Issue 1, article id. L7 (2012) · Accepted for publication in ApJ Letters
openalex publication_date 2012/07/20 · arxiv created 2012/07/23 · arxiv updated 2012/07/25 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present the first results of our spectroscopic follow-up of 6.5 < z < 10 candidate galaxies behind clusters of galaxies. We report the spectroscopic confirmation of an intrinsically faint Lyman break galaxy (LBG) identified as a z 850LP -band dropout behind the Bullet Cluster. We detect an emission line at λ = 9412 Å at >5σ significance using a 16 hr long exposure with FORS2 VLT. Based on the absence of flux in bluer broadband filters, the blue color of the source, and the absence of additional lines, we identify the line as Lyα at z = 6.740 ± 0.003. The integrated line flux is f = (0.7 ± 0.1 ± 0.3) × 10 −17 erg −1 s −1 cm −2 (the uncertainties are due to random and flux calibration errors, respectively) making it the faintest Lyα flux detected at these redshifts. Given the magnification of μ = 3.0 ± 0.2 the intrinsic (corrected for lensing) flux is f int = (0.23 ± 0.03 ± 0.10 ± 0.02) × 10 −17 erg −1 s −1 cm −2 (additional uncertainty due to magnification), which is ∼2–3 times fainter than other such measurements in z ∼ 7 galaxies. The intrinsic H 160W -band magnitude of the object is , corresponding to 0.5 L * for LBGs at these redshifts. The galaxy is one of the two sub- L * LBG galaxies spectroscopically confirmed at these high redshifts (the other is also a lensed z = 7.045 galaxy), making it a valuable probe for the neutral hydrogen fraction in the early universe.