Banner

CAUSTIC Projects

  Home Members Projects Journal Club Publications Collaborators  

Large Scale Cosmic Structure

    Caustics

    The caustic technique is a unique method to estimate the mass of galaxy clusters well beyond the region of dynamical equilibrium. The method is based on galaxy redshifts alone and is complementary to the more popular gravitational lensing techniques. In collaboration with Margaret Geller and Ken Rines at the Harvard-Smithsonian Center for Astrophysics, we have measured the mass profiles of tens of massive and less massive clusters out to a few times the virial radius (e.g. the cluster catalogs CAIRNS and CIRS). With the caustic technique we can also estimate the gravitational potential of galaxy clusters and identify cluster members. Sophisticated tests of the caustic technique with state-of-the-art N-body/hydrodynamical simulations show the reliability of this mass estimation method.
Image 2

    SHELS

    In collaboration with the Harvard-Smithsonian Center for Astrophysics, we have been analyzing the properties of the large-scale distribution of galaxies in a deep redshift survey named SHELS.
Image 2

    AGNS

    We currently work on observations and modelling of the broad-band spectral properties of blazars and young radio galaxies. The emission properties of these objects affect the thermal properties of the interstellar and intergalactic media and can thus play a crucial role in the efficiency of the formation of stars and galaxies. In collaboration with INAF-Torino, INAF-Trieste and the University of Trieste we perform N-body/hydrodynamical simulations of galaxy clusters and large-scale cosmic structure to understand the interplay between the dynamics of dark matter and the processes affecting the baryonic matter (star formation, supernovae explosions, AGN feedback).
Image 2

Alternative Theories of Gravity

    Conformal Gravity

    The Ricci scalar in the Einstein-Hilbert action is replaced by the contraction of the Weyl tensor. This theory does not need dark matter or dark energy to reproduce some of the observed properties of cosmic structures. However, it does have remarkable shortcomings, e.g. low deuterium abundance, divergent gravitational lensing, unrealistic X-ray clusters.
Image 2

    Modified Newtonian Dynamics

    This theory fits astrophysical data at the small scale of galaxies, arguably very well, without the help of dark matter. At large scales MOND still fits the data but needs the help of an 11 eV sterile neutrino. We are now investigating the dynamics of dwarf galaxies both analytically and with numerical N-body simulations with a unique perspective that can explain the missing satellites problem and the unrealistically large velocity dispersions of the ultra-low luminosity dwarfs. Thanks to a conference in Germany, a popular article has been written which shows the value of MOND to explain the origin of the dwarf galaxies of the Milky Way.
Image 2

    Unified Dark Matter Models

    These models describe the dynamics of the universe with a single dark fluid which triggers both the accelerated expansion of the universe at late times and the large-scale structure formation at earlier times. We currently work on the formation of cosmic structure in these models and their related observables.
Image 2