MUSE observations of the lensing cluster Abell 1689

TL;DR

This study uses MUSE integral-field spectroscopy to analyze the core of the lensing cluster Abell 1689, identifying multiple lensed galaxies and sources at high redshift, providing insights into faint galaxy populations and reionization.

Contribution

First spectroscopic census of lensed galaxies in Abell 1689 using MUSE, revealing new high-redshift sources and confirming multiple images without preselection.

Findings

Confirmed 12 images of 7 galaxies via emission lines.

Identified 14 new galaxies with redshifts 0.8 to 6.2.

Detected 17 sources at z > 3, sensitive to faint-end luminosity function slope.

Abstract

We present the results obtained with MUSE on the core of the lensing cluster A1689. Integral-field observations with MUSE provide a unique view of the central region, allowing us to conduct a complete census on both cluster galaxies and lensed background sources, identified based on their spectral features without preselection. We investigate the multiple-image configuration for all known sources in the field. Previous to our survey, 28 different lensed galaxies displaying 46 multiple images were known in the MUSE field of view, most of them based on photometric redshifts and lensing considerations. Among them, we spectroscopically confirm 12 images based on their emission-lines, corresponding to 7 different lensed galaxies between z = 0.95 and 5.0. In addition, 14 new galaxies have been spectroscopically identified in this area, with redshifts ranging between 0.8 and 6.2. All background sources within the MUSE field of view correspond to multiple-imaged systems lensed by A1689. 17 sources in total are found at z > 3 based on their Lyman-alpha emission, with Lyman-alpha luminosities ranging between 40.5 < log(Ly{\alpha}) < 42.5 after correction for magnification. This sample is particularly sensitive to the slope of the LF toward the faintest-end. The density of sources obtained in this survey is consistent with a steep value of {\alpha} < -1.5, although this result still needs further investigation. These results illustrate the efficiency of MUSE in the characterization of lensing clusters on one hand, and the study of faint and distant populations of galaxies on the other hand. In particular, our current survey of lensing clusters should provide a unique census of sources responsible for the reionization in a representative volume at z ~ 4-7.