%0 Generic %1 kashino2019evidence %A Kashino, Daichi %A Lilly, Simon J. %A Shibuya, Takatoshi %A Ouchi, Masami %A Kashikawa, Nobunari %D 2019 %K observations %T Evidence for a highly opaque large-scale galaxy void at the end of reionization %U http://arxiv.org/abs/1909.09077 %X We present evidence that a region of high effective Ly$\alpha$ optical depth at $z\sim5.7$ is associated with an underdense region at the tail end of cosmic reionization. We carried out a survey of Lyman Break Galaxies (LBGs) using Subaru Hyper Suprime-Cam (HSC) in the field of the $z=5.98$ quasar J0148+0600, whose spectrum presents an unusually long ($\sim160 cMpc$) and highly opaque ($\gtrsim7$) Ly$\alpha$ trough at $5.5z5.9$. LBG candidates were selected to lie within the redshift range of the trough, and the projected number densities were measured within 90 cMpc of the quasar sightline. The region within $8'$ (or, $\approx19 cMpc$) of the quasar position is the most underdense of the whole field. This is consistent with the significant deficit of Ly$\alpha$-emitters (LAE) at $z=5.72$ reported by Becker et al., and suggests that the paucity of LAEs is not purely due to removal of the Ly$\alpha$ emission by the high opacity but reflects a real coherent underdensity of galaxies across the entire redshift range of the trough. These observations are consistent with scenarios in which large optical depth fluctuations arise due to fluctuations in the galaxy-dominant UV background or due to residual neutral islands that are expected from reionization that is completed at redshifts as low as $złesssim5.5$.

@misc{kashino2019evidence, abstract = {We present evidence that a region of high effective Ly$\alpha$ optical depth at $z\sim5.7$ is associated with an underdense region at the tail end of cosmic reionization. We carried out a survey of Lyman Break Galaxies (LBGs) using Subaru Hyper Suprime-Cam (HSC) in the field of the $z=5.98$ quasar J0148+0600, whose spectrum presents an unusually long ($\sim160 \mathrm{cMpc}$) and highly opaque ($\tau \gtrsim7$) Ly$\alpha$ trough at $5.5\le z\le 5.9$. LBG candidates were selected to lie within the redshift range of the trough, and the projected number densities were measured within 90 cMpc of the quasar sightline. The region within $8'$ (or, $\approx19 \mathrm{cMpc}$) of the quasar position is the most underdense of the whole field. This is consistent with the significant deficit of Ly$\alpha$-emitters (LAE) at $z=5.72$ reported by Becker et al., and suggests that the paucity of LAEs is not purely due to removal of the Ly$\alpha$ emission by the high opacity but reflects a real coherent underdensity of galaxies across the entire redshift range of the trough. These observations are consistent with scenarios in which large optical depth fluctuations arise due to fluctuations in the galaxy-dominant UV background or due to residual neutral islands that are expected from reionization that is completed at redshifts as low as $z\lesssim5.5$.}, added-at = {2019-09-23T06:45:23.000+0200}, author = {Kashino, Daichi and Lilly, Simon J. and Shibuya, Takatoshi and Ouchi, Masami and Kashikawa, Nobunari}, biburl = {https://www.bibsonomy.org/bibtex/2f4e126089dcf2e61e25dc66f45980c45/rana_7690}, description = {Evidence for a highly opaque large-scale galaxy void at the end of reionization}, interhash = {6111fc2882e49384fc0f8d23fa30b9f3}, intrahash = {f4e126089dcf2e61e25dc66f45980c45}, keywords = {observations}, note = {cite arxiv:1909.09077Comment: 15 pages, 12 figures, submitted to ApJ. Comments welcome}, timestamp = {2019-09-25T22:58:39.000+0200}, title = {Evidence for a highly opaque large-scale galaxy void at the end of reionization}, url = {http://arxiv.org/abs/1909.09077}, year = 2019 }