Periodic Reporting for period 3 - ModGravTrial (Modified Gravity on Trial)
Período documentado: 2021-11-01 hasta 2023-04-30
My research activities following from these questions fall into four main areas: (1) Different representations of gravity allow alternative and simpler approaches to essential problems of general relativity (GR), e.g. to the calculation of energy and entropy of gravitational fields or their canonical quantization. For this reason, I am studying GR from a variety of geometrical and field-theoretical concepts. (2) Generalizations of gravity theory beyond GR underly severe restrictions. I have completed the most extensive classes of such generalizations, and I am studying these with respect to their theoretical consistency, e.g. in view of background stability, absence of ghosts, causality, and well-posedness. (3) Gravity as we observe it is a low-energy effective field theory of an underlying quantum or string theory. I study the implications of quantum corrections for the low-energy sector. This includes also the renormalizability properties of classical Lagrangians, the structure of the arising counterterms, and stringy implications for cosmology. (4) The consequences of the theoretical foundations of gravity for astrophysics, cosmology, and particle physics need to be confronted with empirical evidence. I am working out the observational implications of theoretical ideas, e.g. on gravitational waves, cosmic structures, astrophysical compact objects, and particle physics beyond the standard model. These activities are encapsulated in 6 work packages (WP) of my ERC grant.
regime of gravity theories. The next ESA mission to advance in our comprehension of the universe will be the Euclid satellite. The analysis of Euclid data will require very advanced techniques and, in particular, the availability of N-body simulations to model the non-linear formation of structures in the universe for different cosmological scenarios will be crucial. Our simulations will complement those already existing and those under development by including novel effects derived from more general theories. Similarly, the recently inaugurated field of GWs astronomy by LIGO makes use of extremely advanced interferometers able to detect strains with an accuracy corresponding to one hydrogen-atom radius compared to the astronomical unit. This technology will be pushed even further with the ESA project LISA (whose pathfinder already gave extraordinary results). These measurements also require an exquisite control of the theoretical predictions to properly analyse the data. In particular, it is necessary to have full understanding of the whole process of the merging of compact objects. In the present project, we crucially contribute to an intense exploitation of the products of these two foremost European experiments, which represent two major items in the long-term strategic plans of ESA.