No excess of bright galaxies around the redshift 7.1 quasar ULAS J1120+0641

TL;DR

This study uses Hubble and Spitzer imaging to investigate the galaxy environment around a high-redshift quasar, finding no excess of bright galaxies within 1 Mpc, which informs understanding of early universe galaxy distribution.

Contribution

First detailed search for bright galaxies around a z=7.1 quasar using optical and infrared imaging, showing no excess of such galaxies nearby.

Findings

No excess of >L* galaxies within 1 Mpc of the quasar.

Detection of one galaxy likely at z~2, not associated with the quasar.

Quasar's spectrum consistent with IGM evolution at z>5.5.

Abstract

We present optical and near-infrared imaging of the field of the z=7.0842 quasar ULAS J112001.48+064124.3 taken with the Hubble Space Telescope. We use these data to search for galaxies that may be physically associated with the quasar, using the Lyman break technique, and find three such objects, although the detection of one in Spitzer Space Telescope imaging strongly suggests it lies at z~2. This is consistent with the field luminosity function and indicates that there is no excess of >L* galaxies within 1 Mpc of the quasar. A detection of the quasar shortward of the Ly-alpha line is consistent with the previously observed evolution of the intergalactic medium at z>5.5.