Numerical Simulations of the Large-Scale Structure

Principal Investigator: Pierluigi Monaco


  • Structures in the Universe and Emergent Phenomena


We use numerical techniques to simulate the formation of structures in the Universe, from horizon scales down to galactic scales. We address the following questions: how do we produce large sets of huge simulations, for error estimation in cosmological surveys? what are the main physical processes responsible for the formation of galaxies and galaxy clusters? what are our forecasts for planned and future galaxy surveys?

Status of project and perspectives:

This work is done within the Italian Center for SuperComputing (ICSC), in particular with Spoke 3 on Astrophysics and Cosmos Observations.

Hydro simulations for the formation of galaxies. We have progressed in our description of the sub-grid physics of galaxy formation, including innovative recipes for AGN feedback and dust evolution. We are currently working on an explicit treatment of molecular gas evolution. This allows us to progress in the sophistication of the treatment of the small-scale physics that shapes the properties of galaxies, thus improving our predictive power. These same recipes are used in simulations of galaxy clusters to understand their physics; the production of galaxy cluster simulations for cosmology is described in the “Cosmology with Galaxy Clusters” line of research.

Cosmological simulations for galaxy surveys. We are developing and massively using the PINOCCHIO code for fast simulations; development is progressing along two main avenues, implementation of cosmologies beyond LambdaCDM and technical development for better scaling on supercomputers. The code has been used to produce 1000 huge catalogs of dark matter halos in the past lightcone, covering half of the sky and starting at redshift z=4. Based on these simulations, we provide a large set of mock galaxy catalogs to the Euclid collaboration. These will be the basis for the computation of the numerical covariance matrix for the clustering of the spectroscopic galaxy sample observed by Euclid. This is explained in the “Galaxy Clustering” line of research.

Simulations beyond Newtonian LambdaCDM. We have merged the Particle- Mesh (PM) relativistic Gevolution and the Newtonian Tree-PM Gadget-4 code, so as to have a proper relativistic treatment of clustering on large scales where the Newtonian limit neglects effects that have small but relevant observational consequences. We have developed PINOCCHIO to work with some modified gravity theories, in particular f(R) and cubic galileon. We plan to set up, in the future, an ecosystem of codes for the production of mock galaxy catalogs in a larger set of gravity theories.