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Our Universe in Simulation

Sede A. Riccò Via Santa Sofia 78, Catania

Ongoing and upcoming cosmological surveys—including the Simons Observatory, LiteBIRD, Rubin LSST, Euclid, DESI, PSF, SPHEREx, and the Roman Space Telescope—will deliver observations of unprecedented precision. Joint analyses across these surveys will be essential for uncovering fundamental physics, including the nature of inflation, dark energy, dark matter, neutrino mass, and more. In this talk, I will discuss the opportunities, challenges, and strategies for simulating our universe across multiple wavelengths to realize these goals.In this talk, I will discuss the motivations and objectives of the project, the published results, ongoing studies and the future developments.

Magnetic instabilities and angular momentum transport in red giant core

Sede A. Riccò Via Santa Sofia 78, Catania

The stability of magnetic fields in radiative stellar interiors remains a fundamental open question in understanding the rotational and chemical evolution of low-mass stars. Recent high-resolution asteroseismic observations of red giants have revealed unexpectedly slow core rotations and the presence of strong internal magnetic fields, opening a new window on the internal dynamics of evolved stars. In this talk, I will review the main magnetohydrodynamic instabilities expected in radiative stellar interiors and present new 3D direct numerical simulations of the Tayler instability, a kink-type instability of toroidal magnetic fields prevalent in these regions. By combining simulations, linear stability analysis, and stellar evolution models, we identify where and under what conditions the Tayler instability is likely to operate in red giant cores. These results provide new insight into angular momentum transport in evolved low-mass stars and may also have broader implications for other stars with radiative interiors.

The Nature of Polarized Sources in the MIGHTEE XMM-LSS Deep Field

Sede A. Riccò Via Santa Sofia 78, Catania

This study explores the polarized emission of the faint extragalactic radio sources in the MIGHTEE (MeerKAT International Giga-Hertz Tiered Extragalactic Exploration, Jarvis et al., 2016) survey in order to systematically study cosmic magnetic fields in galaxies to high redshift. Reaching a sensitivity of 1.5 µJy/beam at a resolution of 5 arcseconds, MIGHTEE is providing an opportunity to chart the evolution of polarized emission from distant galaxies over cosmic time.
The MIGHTEE survey detects polarized emission for a large number of radio sources down to total intensity flux densities of the order of 100 µJy. At these flux densities the source population is increasingly dominated by star-forming galaxies (SFGs) as opposed to active galactic nuclei (AGNs). While polarized emission of AGN can be traced to very distant galaxies, polarized emission of SFGs at moderate distance has been detected only once.
I use multi-wavelength criteria to classify MIGHTEE radio objects as either SFG or AGN. I perform Rotation Measure Synthesis (RMSY) on the spectro-polarimetric data cubes and use the polarization and RMSY spectra to search for polarized emission. A comparative analysis of the polarization properties of SFGs and AGNs is performed. The analysis is extended to the lowest possible flux densities using stacking techniques. I will show preliminary results of the MeerKAT polarization studies of radio sources down to a sensitivity at the micro-Jansky level.