TY - JOUR
T1 - Spectroscopic confirmation of a z = 6.740 galaxy behind the bullet cluster
AU - Bradač, Maruša
AU - Vanzella, Eros
AU - Hall, Nicholas
AU - Treu, Tommaso
AU - Fontana, Adriano
AU - Gonzalez, Anthony H.
AU - Clowe, Douglas
AU - Zaritsky, Dennis
AU - Stiavelli, Massimo
AU - Clément, Benjamin
PY - 2012/8/10
Y1 - 2012/8/10
N2 - 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 z850LP-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 Lya flux detected at these redshifts. Given the magnification of μ = 3.0 ± 0.2 the intrinsic (corrected for lensing) flux is fint = (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 mint H160W = 27.57 ± 0.17, corresponding to 0.5L* 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.
AB - 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 z850LP-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 Lya flux detected at these redshifts. Given the magnification of μ = 3.0 ± 0.2 the intrinsic (corrected for lensing) flux is fint = (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 mint H160W = 27.57 ± 0.17, corresponding to 0.5L* 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.
KW - dark ages, reionization, first stars
KW - galaxies: clusters: individual
KW - galaxies: high-redshift
KW - gravitational lensing: strong
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U2 - 10.1088/2041-8205/755/1/L7
DO - 10.1088/2041-8205/755/1/L7
M3 - Article
AN - SCOPUS:84864474686
SN - 2041-8205
VL - 755
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L7
ER -