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We present MOSFIRE spectroscopy of 13 candidate z~8 galaxies selected as Y-dropouts as part of the BoRG pure parallel survey. We detect no significant lya emission (our median 1-sigma rest frame equivalent width sensitivity is in the range 2-16 AA). Using the Bayesian framework derived in a previous paper, we perform a rigorous analysis of a statistical subsample of non-detections for ten Y-dropouts, including data from the literature, to study the cosmic evolution of the lya emission of Lyman Break Galaxies. We find that lya emission is suppressed at z~8 by at least a factor of three with respect to z~6 continuing the downward trend found by previous studies of z-dropouts at z~7. This finding suggests a dramatic evolution in the conditions of the intergalactic or circumgalactic media in just 300 Myrs, consistent with the onset of reionization or changes in the physical conditions of the first generations of starforming regions.
We present the results of a systematic search for galaxies in the redshift range z = 6 - 9, within the new, deep, near-infrared imaging of the Hubble Ultra Deep Field provided by the Wide Field Camera 3 (WFC3) on HST. We have performed full SED fitti
Determining Lya properties of distant galaxies is of great interest for various astrophysical studies. We examine how the strength of Lya emission can be constrained from broad-band SED fits instead of relying on spectroscopy. We use our SED fitting
We present Lya and UV-nebular emission line properties of bright Lya emitters (LAEs) at z=6-7 with a luminosity of log L_Lya/[erg s-1] = 43-44 identified in the 21-deg2 area of the SILVERRUSH early sample developed with the Subaru Hyper Suprime-Cam (
We have taken a deep, moderate-resolution Keck/Deimos spectra of QSO, CFHQS2329, at z=6.4. At the wavelength of Lya, the spectrum shows a spatially-extended component, which is significantly more extended than a stellar spectrum, and also a continuum
Using an i-z dropout criterion, we determine the space density of z~6 galaxies from two deep ACS GTO fields with deep optical-IR imaging. A total of 23 objects are found over 46 arcmin^2, or ~0.5 objects/arcmin^2 down to z~27.3 (6 sigma; all AB mag)