CLEAR: Boosted Ly Transmission of the Intergalactic Medium in UV-bright Galaxies
Academic Article
Overview
Research
Identity
Additional Document Info
Other
View All
Overview
abstract
AbstractReionization is an inhomogeneous process, thought to begin in small ionized bubbles of the intergalactic medium (IGM) around overdense regions of galaxies. Recent Ly studies during the epoch of reionization show evidence that ionized bubbles formed earlier around brighter galaxies, suggesting higher IGM transmission of Ly from these galaxies. We investigate this problem using IR slitless spectroscopy from the Hubble Space Telescope (HST) Wide-Field Camera 3 (WFC3) G102 grism observations of 148 galaxies selected via photometric redshifts at 6.0 < z < 8.2. These galaxies have spectra extracted from the CANDELS Ly Emission at Reionization (CLEAR) survey. We combine the CLEAR data for 275 galaxies with the Keck Deep Imaging Multi-Object Spectrograph and MOSFIRE data set from the Texas Spectroscopic Search for Ly Emission at the End of Reionization Survey. We constrain the Ly equivalent width (EW) distribution at 6.0 < z < 8.2, which is described by an exponential form, dN/dEWexp(EW)/W0, with the characteristic e-folding scale width (W0). We confirm a significant drop in the Ly strength (i.e., W0) at z > 6. Furthermore, we compare the redshift evolution of W0 between galaxies at different UV luminosities. UV-bright (MUV < 21 [i.e., LUV > L*]) galaxies show weaker evolution with a decrease of 0.4 ( 0.2) dex in W0 at z > 6, while UV-faint (MUV > 21 [LUV < L*]) galaxies exhibit a significant drop of 0.70.8 (0.2) dex in W0 from z < 6 to z > 6. If the change in W0 is proportional to the change in the IGM transmission for Ly photons, then this is evidence that the transmission is boosted around UV-brighter galaxies, suggesting that reionization proceeds faster in regions around such galaxies.
