Prof. Lauro Moscardini
phone: (+39) 051-2095726
fax : (+39) 051-2095700
1. HYDRODYMNAMICAL simulations of galaxy clusters and large-scale structure of the universe: Study of the thermodynamics of the intracluster medium during the formation of galaxy clusters, by mean of high-resolution Tree-SPH simulations. In particular, we plan to investigate how and when the accreted substructure reaches hydrostatic equilibrium, the related mass estimates and their reliabilities. Implementation of a code to simulate a virtual telescope in the X-band, including all possible effects affecting real images (background, foreground, cosmic rays, counts in pixels, internal noise, etc.). This tool will be used with numerically simulated clusters in some of the following projects to obtain realistic images which can be directly compared to real observational data. Numerical simulations of high-redshift clusters to study the morphology and dynamics of galaxy clusters and the intra-cluster medium at redshift z>0.5, using hydrodynamical simulations (Tree-SPH). Some data for clusters and possible superclusters at redshift z~1 are now available and comparisons with high-resolution simulations can help in their interpretation. Analysis of a cosmological hydrodynamical simulation of a representative volume of the universe, with high enough resolution to describe in detail the X-ray and SZ properties of the baryonic intergalactic medium in groups and clusters of galaxies and within large-scale filaments.
(The large scale distribution of gas in a LCDM model at redshift z=0. The box size is 192 Mpc/h and the slice tickness is 1/16th. Courtesy of S. Borgani )
Main collaborators: V. Springel (Garching), K. Dolag, M. Meneghetti, E. Rasia, G. Tormen (Padova), A. Diaferio, G. Murante (Torino), S. Borgani, L. Tornatore, P. Tozzi (Trieste)
2. Gravitational lensing: Numerical simulations of the strong-lensing properties of galaxy clusters, with special attention to the consequences due to the inclusion of observational effects, as atmospheric seeing, photonic noise in the CCD pixels, brightness of the night sky, and extraction of sources from noisy images. Starting from N-body simulations of single clusters, and using ray-shooting techniques, we plan to study several statistics of gravitational arcs (length, width, curvature radius, length to width ratio). We will consider a realistic redshift distribution of the background sources. Their lensed images will be identified and classified using the same techniques adopted to analyze observational images (i.e. SExtractor). Analytical models of arc statistics in different cosmologies, to constrain cosmological parameter, with particular attention to the quintessence models. The results obtained at the previous point may be used in connection with Press-Schechter like models to determine the optical depth of arcs in different cosmological models.
(Logarithmic map of the temperature for a galaxy cluster simulated at very high resolution. Courtesy of K. Dolag.)
Main collaborators: M. Bartelmann (Garching),K. Dolag, M. Maturi, M. Meneghetti, G. Tormen, E. Torri (Padova), C. Baccigalupi, F. Perrotta (Trieste)
3. Models for clustering evolution: computation of the theoretical predictions of clustering expected for galaxies, clusters, AGN and EROs in the framework of different cosmological models. We will use updated models for the bias factor, based on the luminosity function or abundances of the objects and including the dependence on their physical properties. For galaxies, the comparison to the observational data will allow us to constrain the formation redshift, the halo occupation number and the relative importance of merging events vs. passive evolution. For AGNs it will be possible to constrain their duty cycle and the properties of the central black holes (mass and efficiency) as a function of redshift. Finally, for clusters, thanks to more reliable relations between the observational quantities and the mass of the hosting dark matter haloes, it will possible to put constraints on the cosmological parameters.
Main collaborators: G. de Zotti, S. Matarrese (Padova), A. Grazian (Roma), S. Cristiani, M. Magliocchetti, M. Negrello (Trieste).
|Last update: 18/08/2005||