Tunable filter imaging of high redshift quasar fields

TL;DR

This study used tunable filter imaging to identify candidate Lyman alpha emitters around high redshift quasars, revealing a significant galaxy overdensity at z~4.5 in one of the observed fields.

Contribution

First application of the Taurus Tunable Filter to search for Lyman alpha emitters in high redshift quasar fields, demonstrating its effectiveness in detecting galaxy overdensities.

Findings

Detected candidate emission line galaxies in all three fields.

Found a significant galaxy overdensity at z~4.5 near BR B0019-1522.

Estimated galaxy density consistent with large-scale structure formation models.

Abstract

We have used the Taurus Tunable Filter to search for Lyman alpha emitters in the fields of three high redshift quasar fields: two at z~2.2 (MRC B1256-243 and MRC B2158-206) and one at z~4.5 (BR B0019-1522). Our observations had a field of view of around 35 square arcminutes, and reached AB magnitudes of magnitudes of ~21 (MRC B1256-243), ~22 (MRC B2158-206), and ~22.6 (BR B0019-1522), dependent on wavelength. We have identified candidate emission line galaxies in all three of the fields, with the higher redshift field being by far the richest. By combining our observations with simulations of the instrumental response, we estimate the total density of emission line galaxies in each field. Seventeen candidate emission line galaxies were found in within 1.5 Mpc of BR0019-1522, a number density of 4.9 +/- 1.2 x 10^-3 Mpc^-3, suggesting a significant galaxy overdensity at z~4.5.