The merging cluster Abell 1758 revisited: multi-wavelength observations and numerical simulations (1102.2175v2)

Abstract: [Abriged] We discuss here the properties of the double cluster Abell 1758, at a redshift z~0.279, which shows strong evidence for merging. We analyse the optical properties of the North and South clusters of Abell 1758 based on deep imaging obtained with the CFHT archive Megaprime/Megacam camera in the g' and r' bands, covering a total region of about 1.05 x 1.16 deg^2. Our X-ray analysis is based on archive XMM-Newton images. Numerical simulations were performed using an N-body algorithm to treat the dark matter component, a semi-analytical galaxy formation model for the evolution of the galaxies and a grid-based hydrodynamic code with a PPM scheme for the dynamics of the intra-cluster medium. We have computed galaxy luminosity functions (GLFs) and 2D temperature and metallicity maps of the X-ray gas, which we then compared to the results of our numerical simulations. The GLFs of Abell 1758 North are well fit by Schechter functions in the g' and r' bands, but a small excess of bright galaxies, particularly in the r' band. On the contrary, the GLFs of Abell 1758 South are not well fit by Schechter functions: excesses of bright galaxies are seen in both bands. Comparing observational results to those derived from numerical simulations, we could mimic the most prominent features present in the metallicity map and propose an explanation for the dynamical history of the cluster. Particilarly, we found in particular that in the metal rich elongated regions of the North cluster, winds had been more efficient in transporting metal enriched gas to the outskirts than ram pressure stripping. We confirm the merging structure of each of the North and South clusters, both at optical and X-ray wavelengths.