The effect of ionizing background fluctuations on the spatial correlations of high redshift Ly$\alpha$-emitting galaxies

TL;DR

This study explores how fluctuations in the ultraviolet background at high redshifts can significantly influence the observed clustering of Lyα-emitting galaxies, affecting interpretations of their distribution and evolution.

Contribution

It demonstrates that UV background fluctuations can dominate galaxy clustering signals at high redshifts, expanding the range of models consistent with observations and influencing bias factor estimates.

Findings

UVBG fluctuations can enhance galaxy clustering on scales up to a few hundred arcsecs.

Allowing UVBG fluctuations broadens the acceptable bias factor range for Lyα emitters.

The halo mass of Lyα-emitting galaxies remains nearly constant at about 10^{10.5} solar masses from redshift 3 to 7.

Abstract

We investigate the possible influence of fluctuations in the metagalactic photoionizing ultra-violet background (UVBG) on the clustering of Ly$\alpha$-emitting galaxies through the modulation of the ionization level of the gas surrounding the systems. At redshifts $z > 5$, even when assuming the reionization of the intergalactic medium has completed, the fluctuations are sufficiently large that they may non-negligibly enhance, and possibly even dominate, the angular correlation function on scales up to a few hundred arcsecs. Whilst a comparison with observations at $z \sim 5.7$ is statistically consistent with no influence of UVBG fluctuations, allowing for the fluctuations opens up the range of acceptable models to include those with relatively low bias factors for the Ly$\alpha$-emitting galaxies. In this case, the evolution in the bias factor of Ly$\alpha$-emitters over the approximate redshift range $3 < z < 7$ corresponds to a nearly constant halo mass for Ly$\alpha$-emitting galaxies of $\sim 10^{10.5}\,M_\odot$.