%0 Generic %1 davies2019ionization %A Davies, Frederick B. %D 2019 %K library %T Ionization bias and the ghost proximity effect near $z\gtrsim6$ quasars in the shadow of proximate absorption systems %U http://arxiv.org/abs/1904.10459 %X The larger-than-expected scatter in the opacity of the Ly$\alpha$ forest suggests that the metagalactic ionizing background is strongly fluctuating at $z > 5.5$. Models for ionizing background fluctuations predict a strong positive bias on large scales, so the environments of massive $>10^12\,\rm M_ødot$ dark matter halos, e.g. $z\sim6$ quasar hosts, would be ideal laboratories to constrain the sources of ionizing photons. While the quasars themselves should overwhelm any plausible ionizing photon contribution from neighboring galaxies, proximate damped Ly$\alpha$ absorbers (DLAs) have recently been discovered in the foreground of $z\sim6$ quasars, and the Ly$\alpha$ forest in the shadow of these DLAs could probe the local ionization environment. Using Gpc$^3$ simulations of $z=6$ ionizing background fluctuations, we show that while the Ly$\alpha$ forest signal from ionization bias around a quasar host halo should be strong, it is likely suppressed by the associated intergalactic matter overdensity. We also show that the quasar itself may still overwhelm the clustering signal via a "ghost" of the proximity effect from the quasar radiation causing a large-scale bias in the ionizing photon mean free path. This ghost proximity effect is sensitive to the lifetime and geometry of quasar emission, potentially unlocking a new avenue for constraining these fundamental quasar properties. Finally, we present observations of a $z\sim6$ quasar with a proximate DLA which shows a strong excess in Ly$\alpha$ forest transmission at the predicted location of the ghost proximity effect.

@misc{davies2019ionization, abstract = {The larger-than-expected scatter in the opacity of the Ly$\alpha$ forest suggests that the metagalactic ionizing background is strongly fluctuating at $z > 5.5$. Models for ionizing background fluctuations predict a strong positive bias on large scales, so the environments of massive $>10^{12}\,{\rm M}_\odot$ dark matter halos, e.g. $z\sim6$ quasar hosts, would be ideal laboratories to constrain the sources of ionizing photons. While the quasars themselves should overwhelm any plausible ionizing photon contribution from neighboring galaxies, proximate damped Ly$\alpha$ absorbers (DLAs) have recently been discovered in the foreground of $z\sim6$ quasars, and the Ly$\alpha$ forest in the shadow of these DLAs could probe the local ionization environment. Using Gpc$^3$ simulations of $z=6$ ionizing background fluctuations, we show that while the Ly$\alpha$ forest signal from ionization bias around a quasar host halo should be strong, it is likely suppressed by the associated intergalactic matter overdensity. We also show that the quasar itself may still overwhelm the clustering signal via a "ghost" of the proximity effect from the quasar radiation causing a large-scale bias in the ionizing photon mean free path. This ghost proximity effect is sensitive to the lifetime and geometry of quasar emission, potentially unlocking a new avenue for constraining these fundamental quasar properties. Finally, we present observations of a $z\sim6$ quasar with a proximate DLA which shows a strong excess in Ly$\alpha$ forest transmission at the predicted location of the ghost proximity effect.}, added-at = {2019-04-25T05:07:53.000+0200}, author = {Davies, Frederick B.}, biburl = {https://www.bibsonomy.org/bibtex/27e8e83ad0855e6b36b193f3d658885bb/gpkulkarni}, description = {Ionization bias and the ghost proximity effect near $z\gtrsim6$ quasars in the shadow of proximate absorption systems}, interhash = {0ab604b251fa7da43da9cc21b91b25e4}, intrahash = {7e8e83ad0855e6b36b193f3d658885bb}, keywords = {library}, note = {cite arxiv:1904.10459Comment: 12 pages, 17 figures, submitted to MNRAS}, timestamp = {2019-04-25T05:07:53.000+0200}, title = {Ionization bias and the ghost proximity effect near $z\gtrsim6$ quasars in the shadow of proximate absorption systems}, url = {http://arxiv.org/abs/1904.10459}, year = 2019 }