TY - JOUR
T1 - A persistent excess of galaxy-galaxy strong lensing observed in galaxy clusters
AU - Meneghetti, Massimo
AU - Cui, Weiguang
AU - Rasia, Elena
AU - Yepes, Gustavo
AU - Acebron, Ana
AU - Angora, Giuseppe
AU - Bergamini, Pietro
AU - Borgani, Stefano
AU - Calura, Francesco
AU - Despali, Giulia
AU - Giocoli, Carlo
AU - Granata, Giovanni
AU - Grillo, Claudio
AU - Knebe, Alexander
AU - Macciò, Andrea V.
AU - Mercurio, Amata
AU - Moscardini, Lauro
AU - Natarajan, Priyamvada
AU - Ragagnin, Antonio
AU - Rosati, Piero
AU - Vanzella, Eros
N1 - Publisher Copyright:
© 2023 EDP Sciences. All rights reserved.
PY - 2023/10/1
Y1 - 2023/10/1
N2 - 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.
AB - 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.
KW - Dark matter
KW - Galaxies: clusters: general
KW - Gravitational lensing: strong
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U2 - 10.1051/0004-6361/202346975
DO - 10.1051/0004-6361/202346975
M3 - Article
AN - SCOPUS:85174203130
SN - 0004-6361
VL - 678
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - L2
ER -