Strong Gravity News & Events

We got together on May 20th 2026 at Etevaldo's favourite restaurant in Aveiro (O Telheiro), to celebrate his 4.5 years in Gr@v. In the same day we had an excellent seminar from Hryhorii Ovcharenko, visiting from Prague. Etevaldo is now starting a post-doctoral position in Brazil. Many thanks, Etevaldo, for being with us. See you soon!

We investigate the absorption of massless scalar waves by three distinct hairy black hole solutions obtained through the gravitational decoupling method, considering  the weak, the strong or the dominant energy conditions.

Charged boson stars serve as models for exploring how self-interaction and electromagnetic charge influence the stability and evolution of compact objects. In this seminar, I will present results from numerical relativity simulations identifying a critical charge that serves as a threshold for stable configurations.

In early May 2026 we received the visits of our collaborators Nico Sanchis Gual, Isa Cordero, Gabriele Palloni, Claudio Lazarte (Valencia, Spain), members of the NewFunFiCO network, as well as Carolina Benone (UFPA, Brazil) and Carlos Joaquin (UNAM, Mexico), who joined us to celebrate the successful Ph.D. exam of Etevaldo Costa. 

Etevaldo Costa successfully defended his Ph.D. thesis with title "Bosonic exotic compact objects: construction and physical properties". The thesis was supervised by C. Herdeiro and E. Radu and the committee included Eric Gourgoulhon, Daniela Doneva and Carolina Benone as examiners. Congratulations Etevaldo!

A four months grant for a student enrolled in a doctorate programme is open, to start on June 1st 2026. More informations here. 

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.