MUSE observations of the lensing cluster Abell 1689

Abstract

Context. This paper presents the results obtained with the Multi Unit Spectroscopic Explorer (MUSE) for the core of the lensing cluster Abell 1689, as part of MUSE's commissioning at the ESO Very Large Telescope. Aims. Integral-field observations with MUSE provide a unique view of the central 1 × 1 arcmin 2 region at intermediate spectral resolution in the visible domain, allowing us to conduct a complete census of both cluster galaxies and lensed background sources. Methods. We performed a spectroscopic analysis of all sources found in the MUSE data cube. Two hundred and eighty-two objects were systematically extracted from the cube based on a guided-and-manual approach. We also tested three different tools for the automated detection and extraction of line emitters. Cluster galaxies and lensed sources were identified based on their spectral features. We investigated the multiple-image configuration for all known sources in the field. Results. Previous to our survey, 28 different lensed galaxies displaying 46 multiple images were known in the MUSE field of view, most of them were detected through photometric redshifts and lensing considerations. Of these, 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 thanks to MUSE data, with redshifts ranging between 0.8 and 6.2. All background sources detected within the MUSE field of view correspond to multiple-imaged systems lensed by A1689. Seventeen sources in total are found at z ≥ 3 based on their Lyman-α emission, with Lyman-α luminosities ranging between 40.5 log(Lyα) 42.5 after correction for magnification. This sample is particularly sensitive to the slope of the luminosity function toward the faintest end. The density of sources obtained in this survey is consistent with a steep value of α ≤ −1.5, although this result still needs further investigation. Conclusions. These results illustrate the efficiency of MUSE in characterizing lensing clusters on one hand and in studying faint and distant populations of galaxies on the other hand. In particular, our current survey of lensing clusters is expected to provide a unique census of sources responsible for the reionization in a representative volume at z ∼ 4−7.

A gravitationally-boosted MUSE survey for emission-line galaxies at z ≳ 5 behind the massive cluster RCS 0224

“…While these observations require integration times of ∼30 h, similar sources can potentially be found behind by strong lensing clusters within reasonable integrations times (e.g. Karman et al 2015;Bina et al 2016).…”

The MUSE Hubble Ultra Deep Field Survey

“…spectroscopically-confirmed LAEs in a homogeneous manner (Bacon et al 2015, Drake et al 2017 as well as probing the lensed LAE populations behind galaxy clusters (Bina et al 2016, Smit et al 2017. In addition to the ability of MUSE to perform as a 'detection machine' for star-forming galaxies, the deep datacubes allow us to establish reliable total Lyα line fluxes by ensuring we capture the total width of the Lyα line in wavelength, and the full extent of each object on-sky.…”

A 16 deg2 survey of emission-line galaxies at z < 1.5 in HSC-SSP Public Data Release 1

“…However, target selection for spectroscopy can cause biases with the observed galaxy sample. Rather than slit or fiber spectroscopy, an integral field unit spectrograph such as VLT/MUSE (Bacon et al 2015;Meillier et al 2016;Bina et al 2016;Swinbank et al 2017) or grism such as HST/WFC3 (e.g., Atek et al 2010;van Dokkum et al 2011;Straughn et al 2011;van der Wel et al 2011;Brammer et al 2012;Colbert et al 2013;Pirzkal et al 2013;Mehta et al 2015;Morris et al 2015;Momcheva et al 2016) can overcome selection biases by allowing us to get spectrum of all galaxies over the field surveyed. One weakness is the small field of view (FoV).…”