The Flux Auto- and Cross-Correlation of the Lyman-alpha Forest. I. Spectroscopy of QSO Pairs with Arcminute Separations and Similar Redshifts

TL;DR

This paper presents moderate-resolution spectroscopic observations of QSO pairs at high redshift to study the Lyman-alpha forest's auto- and cross-correlation, aiming to improve cosmological constraints and understand absorber coherence.

Contribution

It provides new spectroscopic data of QSO pairs at z > 2.2 with small angular separations, enabling advanced analysis of the Lyman-alpha forest's correlation properties and cosmological applications.

Findings

Spectroscopic data of 7 QSOs, 35 pairs, and 1 triplet collected.

Revisions made to previously published QSO redshifts.

Data suitable for studying absorber coherence and proximity effects.

Abstract

The Lyman-alpha forest has opened a new redshift regime for cosmological investigation. At z > 2 it provides a unique probe of cosmic geometry and an independent constraint on dark energy that is not subject to standard candle or ruler assumptions. In Paper I of this series on using the Lyman-alpha forest observed in pairs of QSOs for a new application of the Alcock-Paczynski test, we present and discuss the results of a campaign to obtain moderate-resolution spectroscopy (FWHM ~ 2.5 Angstroms) of the Lyman-alpha forest in pairs of QSOs with small redshift differences (Delta z < 0.25, z > 2.2) and arcminute separations (< 5'). This data set, composed of seven individual QSOs, 35 pairs, and one triplet, is also well-suited for future investigations of the coherence of Lyman-alpha absorbers on ~ 1 Mpc transverse scales and the transverse proximity effect. We note seven revisions for previously published QSO identifications and/or redshifts.