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A persistent excess of galaxy-galaxy strong lensing observed in galaxy clusters

Authors :
Meneghetti, Massimo
Cui, Weiguang
Rasia, Elena
Yepes, Gustavo
Acebron, Ana
Angora, Giuseppe
Bergamini, Pietro
Borgani, Stefano
Calura, Francesco
Despali, Giulia
Giocoli, Carlo
Granata, Giovanni
Grillo, Claudio
Knebe, Alexander
Macciò, Andrea
Mercurio, Amata
Moscardini, Lauro
Natarajan, Priyamvada
Ragagnin, Antonio
Rosati, Piero
Vanzella, Eros
Source :
A&A 678, L2 (2023)
Publication Year :
2023

Abstract

Previous studies have revealed that the estimated probability of galaxy-galaxy strong lensing in observed galaxy clusters exceeds the expectations from the $\Lambda$ Cold Dark Matter cosmological model by one order of magnitude. We aim to understand the origin of this excess by analyzing a larger set of simulated galaxy clusters and investigating how the theoretical expectations vary under different adopted prescriptions and numerical implementations of star formation and feedback in simulations. We perform a ray-tracing analysis of 324 galaxy clusters from the Three Hundred project, comparing the Gadget-X and Gizmo-Simba runs. These simulations, which start from the same initial conditions, are performed with different implementations of hydrodynamics and galaxy formation models tailored to match different observational properties of the Intra-Cluster-Medium and cluster galaxies. We find that galaxies in the Gizmo-Simba simulations develop denser stellar cores than their Gadget-X counterparts. Consequently, their probability for galaxy-galaxy strong lensing is higher by a factor of $\sim 3$. This increment is still insufficient to fill the gap with observations, as a discrepancy by a factor $\sim 4$ still persists. In addition, we find that several simulated galaxies have Einstein radii that are too large compared to observations. We conclude that a persistent excess of galaxy-galaxy strong lensing exists in observed galaxy clusters. The origin of this discrepancy with theoretical predictions is still unexplained in the framework of the cosmological hydrodynamical simulations. This might signal a hitherto unknown issue with either the simulation methods or our assumptions regarding the standard cosmological model.<br />Comment: 6 pages, 2 figures, accepted for publication on A&A Letters. See companion paper Srivastava et al. (2023)

Details

Database :
arXiv
Journal :
A&A 678, L2 (2023)
Publication Type :
Report
Accession number :
edsarx.2309.05799
Document Type :
Working Paper
Full Text :
https://doi.org/10.1051/0004-6361/202346975