Exploring the early universe with gravitational waves and primordial magnetic fields

The title is: 'Exploring the early universe with gravitational waves and primordial magnetic fields'

The main goal of the project is to use gravitational astronomy to improve our understanding of the early universe at its highest energy scales. We study the generation of cosmological gravitational wave (GW) backgrounds produced by primordial turbulence in the early universe. In particular, we aim to analyse different mechanisms leading to the production of turbulence and magnetic fields. Both phenomena produce inevitably magnetohydrodynamic (MHD) turbulence in the primordial plasma due to the large induced velocities and the high conductivity of the early universe, and it requires fully numerical simulations of the velocity and magnetic field dynamics to accurately model the generated stochastic GW background and the posterior evolution of the magnetic field up to our present time. Hence, to perform the analyses, we will be combining theoretical calculations with large resolution numerical simulations of MHD turbulence coupled to linearized general relativity, using the open-source Pencil Code, at high-performance computing infrastructures. Using the results of such simulations, we aim to develop a template for the production of GWs due to MHD turbulence that is of paramount importance for the future successful detection of early universe signals with the Laser Interferometer Space Antenna (LISA), pulsar timing arrays, and other GW detectors. Additionally, primordial magnetic fields can be probed by observations from distant TeV gamma-ray sources using the Fermi Observatory and, in the near future, the Cerenkov Telescope Array, allowing us to put lower limits on the strength of the relics of primordial magnetic fields. Such multi-messenger detections can shed light on our understanding of the early universe physics and provide an answer to fundamental open questions in cosmology like the baryon asymmetry problem, the electroweak hierarchy problem, or the nature of dark matter, by directly probing the physics of the early universe, e.g., first-order phase transitions, parity-odd violation processes, or axion fields.