Recent investigations into non-vacuum general relativity and parametrized spacetimes have reported viable black hole solutions that admit multiple photon spheres. Investigations of these black holes through their shadows often suffer from parameter degeneracy.
Gravitational-wave (GW) observations have significantly advanced our understanding of stellar-origin compact objects. Current detectors could, in principle, also observe exotic compact objects (ECOs) acting as black-hole mimickers and interacting only gravitationally with visible matter.
Neutron stars offer unique natural laboratories for probing the interaction between dark matter and baryonic matter — a central open question in modern astrophysics and high-energy physics. In this talk, I will present our recent work modeling dark matter as an ultralight bosonic field that accretes onto neutron stars, forming composite objects — fermion-boson stars — bound through gravity.
We present a large family of twisting and expanding solutions to the Einstein-Maxwell equations of algebraic type D, for which the two double principal null directions (PNDs) of the Weyl tensor are not aligned with the null eigendirections of the Faraday tensor. In addition to systematically deriving this new class, we present its various metric forms and convenient parameterizations.
In April 2026 we received the visits of Maryem Jemri (Rabat) and Justin Feng (Prague). Thank you for your seminars and the great scientific interactions!
Inspired by noncommutative geometry in string theory, we introduce extended derivatives in black hole physics by incorporating a real antisymmetric rank-2 tensor, exhibiting similarities with certain string-theoretic fields.
Gr@v is hosting the visits of Yasha Shnir, long time group collaborator, under an FCT mobility grant, and Mario Luciano Navarro, Ph.D. student from Valencia in the spring 2026. In the photo Yasha and Mario enjoy a bit of sunshine after the weekly group lunch.
We present and study new nontopological soliton solutions in the U(1) gauged nonlinear O(3) sigma-model with a symmetry breaking potential in 3+1 dimensional space-time. The configurations are endowed with an electric and magnetic field and also carry a nonvanishing angular momentum density.
This talk presents two distinct problems in gravitational physics that are connected through the use of solution-generating techniques within Einstein–Maxwell–scalar theory. First, we construct new vacuum solutions of Einstein’s equations starting from electrovacuum configurations embedded in external electromagnetic backgrounds.
Our group coordinated the "Numerical Relativity and High Energy Physics" IRSES network (2012-2015). Here is a list of the global network meetings organized:
