Context. Previous studies have revealed that the estimated probability of galaxy-galaxy strong lensing in observed galaxy clusters exceeds the expectations from the Λ cold dark matter cosmological model by one order of magnitude. Aims. 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. Methods. We performed 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, were performed with different implementations of hydrodynamics and galaxy formation models tailored to match different observational properties of the intracluster medium and cluster galaxies. Results. 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 ∼3. This increment is still insufficient to fill the gap with observations as a discrepancy by a factor ∼4 still persists. In addition, we find that several simulated galaxies have Einstein radii that are too large compared to observations. Conclusions. 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.

A persistent excess of galaxy-galaxy strong lensing observed in galaxy clusters / M. Meneghetti, W. Cui, E. Rasia, G. Yepes, A. Acebron, G. Angora, P. Bergamini, S. Borgani, F. Calura, G. Despali, C. Giocoli, G. Granata, C. Grillo, A. Knebe, A.V. Macci??, A. Mercurio, L. Moscardini, P. Natarajan, A. Ragagnin, P. Rosati, E. Vanzella. - In: ASTRONOMY & ASTROPHYSICS. - ISSN 1432-0746. - 678:(2023), pp. L2.1-L2.6. [10.1051/0004-6361/202346975]

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

A. Acebron;P. Bergamini;G. Granata;C. Grillo;
2023

Abstract

Context. Previous studies have revealed that the estimated probability of galaxy-galaxy strong lensing in observed galaxy clusters exceeds the expectations from the Λ cold dark matter cosmological model by one order of magnitude. Aims. 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. Methods. We performed 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, were performed with different implementations of hydrodynamics and galaxy formation models tailored to match different observational properties of the intracluster medium and cluster galaxies. Results. 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 ∼3. This increment is still insufficient to fill the gap with observations as a discrepancy by a factor ∼4 still persists. In addition, we find that several simulated galaxies have Einstein radii that are too large compared to observations. Conclusions. 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.
Dark matter; Galaxies: clusters: general; Gravitational lensing: strong
Settore FIS/05 - Astronomia e Astrofisica
   Zooming into Dark Matter and proto-galaxies with massive lensing clusters
   MINISTERO DELL'ISTRUZIONE E DEL MERITO
   2017WSCC32_002

   GRAvitational lensing in galaxy clusters next-generation proposAL
   GRAAL
   MINISTERO DELL'ISTRUZIONE E DEL MERITO
   2020SKSTHZ_001
2023
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/1019979
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