Improved strong lensing modelling of galaxy clusters using the Fundamental Plane: Detailed mapping of the baryonic and dark matter mass distribution of Abell S1063

Abstract

Aims. From accurate photometric and spectroscopic information, we build the Fundamental Plane (FP) relation for the early-type galaxies of the cluster Abell S1063. We use this relation to develop an improved strong lensing model of the cluster, and we decompose the cluster’s cumulative projected total mass profile into its stellar, hot gas, and dark matter mass components. We compare our results with the predictions of cosmological simulations. Methods. We calibrate the FP using Hubble Frontier Fields photometry and data from the Multi Unit Spectroscopic Explorer on the Very Large Telescope. The FP allows us to determine the velocity dispersions of all 222 cluster members included in the model from their measured structural parameters. As for their truncation radii, we test a proportionality relation with the observed half-light radii. Fixing the mass contribution of the hot gas component from X-ray data, the mass density distributions of the diffuse dark matter haloes are optimised by comparing the observed and model-predicted positions of 55 multiple images of 20 background sources distributed over the redshift range 0.73 − 6.11. We determine the uncertainties on the model parameters with Monte Carlo Markov chains. Results. We find that the most accurate predictions of the positions of the multiple images are obtained when the truncation radii of the member galaxies are approximately 2.3 times their effective radii. Compared to earlier work on the same cluster, our model allows for the inclusion of some scatter on the relation between the total mass and the velocity dispersion of the cluster members. We notice a lower statistical uncertainty on the value of some model parameters. For instance, the main dark matter halo of the cluster has a core radius of 86 ± 2 kpc: the uncertainty on this value decreases by more than 30% with respect to previous work. Taking advantage of a new estimate of the stellar mass of all cluster members from the HST multi-band data, we measure the cumulative two-dimensional mass profiles out to a radius of 350 kpc for all baryonic and dark matter components of the cluster. At the outermost radius of 350 kpc, we obtain a baryon fraction of 0.147 ± 0.002. We study the stellar-to-total mass fraction of the high-mass cluster members in our model, finding good agreement with the observations of wide galaxy surveys and some disagreement with the predictions of halo occupation distribution studies based on N-body simulations. Finally, we compare the features of the sub-haloes as described by our model with those predicted by high-resolution hydrodynamical simulations. We obtain compatible results in terms of the stellar over total mass fraction. On the other hand, we report some discrepancies both in terms of the maximum circular velocity, which is an indication of the halo compactness, and the sub-halo total mass function in the central cluster regions.

The probability of galaxy-galaxy strong lensing events in hydrodynamical simulations of galaxy clusters

“…Integral field observations with the Multi-Unit Spectroscopic Explorer (MUSE) at the VLT have contributed invaluably to strong lensing modeling (see, e.g. Karman et al 2015;Grillo et al 2015Grillo et al , 2016Vanzella et al 2021;Caminha et al 2019;Jauzac et al 2021;Bergamini et al 2021;Richard et al 2021;Granata et al 2022). Thanks to its tremendous efficiency and sensitivity to line emitters, this instrument has expanded the list of confirmed strongly lensed galaxies available for mapping the matter distribution and made unprecedented resolution possible in several galaxy clusters.…”

A Spectroscopic View of the JWST/GTO Strong Lensing Cluster A1489

“…Here we discuss a spectroscopic survey of A1489 that includes redshifts for 195 members. We also provide central stellar velocity dispersions; these observations promise enhancement of constraints on lensing models (e.g., Monna et al 2017;Bergamini et al 2019;Acebron et al 2021;Granata et al 2022).…”

“…Use of this set of dispersions will enhance constraints on the strong lensing models. The data set for A1489 is larger than the one for A383 (Monna et al 2015) but smaller than the recent sample used by Granata et al (2022) to analyze the cluster Abell S1063. A more complete sample of high-dispersion objects and extension of the sample of dispersions to fainter cluster members would provide even stronger constraints.…”

“…Concurrent constraints on the mass of the cluster halo improve by ∼10%. Application to other systems underscores the enhanced lens models enabled by the use of central velocity dispersions (e.g., Monna et al 2017;Bergamini et al 2019;Acebron et al 2021;Granata et al 2022).…”

Galaxies in the central regions of simulated galaxy clusters

“…First off, in the following analyses, we focus primarily on SHs with M SH > 2 × 10 10 h −1 M , whose inner structure is resolved with 100 particles. In each region we focus on the main central halo at z = 0.4, in order to consistently compare the redshift of observations presented in Bergamini et al (2019) and Granata et al (2022). We consider three orthogonal lines-of-sight to each cluster halo, and extract all SHs in cylinders with depth 10 comoving Mpc/h and radius R < 0.15R vir centred on the halo centre.…”