Informazioni sull’evento

02/09/2018

Astrophysics Talk

Strong-lensed galaxies in simulated and observed galaxy clusters

Antonio Ragagnin (Unibo-DIFA)

Tuesday 14/02/2023 @ 14:00, Sala IV piano Battiferro - Presenza + remoto

Recent observations found that observed cluster member galaxies are more compact than their counterparts in LCDM numerical works, as indicated by the difference in their strong gravitational lensing properties. In particular, measured and simulated galaxy-galaxy strong lensing events on small scales are discrepant by one order of magnitude. Among the possible explanations for this discrepancy some studies suggest that simulations with better resolution and implementing different schemes for galaxy formation could produce simulations that are in better agreement with the observations. We found that regardless of the adopted numerical resolution and feedback model, simulations are not able to increase the compactness of low mass subhaloes, which however is the most relevant mass range for galaxy galaxy strong lensing. While for what concern high mass subhaloes, a change in AGN energy feedback can possibly increase their compactness to match observations, however, with the price of producing irrealistically overly-bright massive galaxies. We conclude that LCDM simulations are unable to simultaneously reproduce the observed stellar masses and compactness (or maximum circular velocities) of galaxy clusters. Thus, there is still a discrepancy between numerical works performed within the LCDM scenario and observations.