Line of research overview

Numerical Simulations of the Large-Scale Structure

Principal Investigator: Pierluigi Monaco

Abstract:

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.

Simulations for the formation of galaxies, with full hydro or semi-analytic techniques. We have progressed in our modelling of the sub-grid physics of galaxy formation, including innovative prescriptions for AGN feedback and dust evolution. We are involved in several further developments of our modelling to progress in the sophistication of the treatment of the small-scale physics that shapes the properties of galaxies, thus improving our predictive power. The relation of their (predicted and observed) properties with the surrounding environment is described in the Galaxies in their cosmic web line of research. These same prescriptions are used in simulations of galaxy clusters to understand their physics, and to investigate how to extract cosmological information from them, as described in the Large-Scale Structure line of research. We are actively involved in the prediction of X-ray mock emission from simulated galaxy clusters for comparisons with various X-ray observational campaigns, with the aim of studying their thermodynamical and chemical properties

Cosmological simulations for galaxy surveys. We are developing and massively using the PINOCCHIO code for fast simulations; development is progressing along two main avenues, improvement of its accuracy 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 Consortium. These will be the basis for the computation of the numerical covariance matrix for the clustering of the spectroscopic galaxy sample observed by Euclid, as explained in the Large-Scale Structure line of research. We also have simulated cosmologies with large-scale inhomogeneities to model structure growth on an inhomogeneous background.

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.