In a paper published in Physical Review Letters, Gr@v researchers Pedro Cunha and Eugen Radu (in collaboration with Carlos Herdeiro from IST-Lisbon) provide a new insight on how spin could mask non-GR features in astrophysical black holes.
On May 29th 1919 Eddington and Cottingham measured the position of stars near the sun during a total eclipse observed at the island of Príncipe, off the west African coast. Their results, together with the ones of another expedition undertaken by Crommelin and Davidson to Sobral (Brazil), were announced on November 6th 1919 and confirmed the General Theory of Relativity. This openned a new era in our understanding of gravity, space, time and matter... and made Einstein world famous.
In this talk I describe a new class of superradiant instabilities in which ultralight scalar fields extract rotational energy from neutron stars. The instability arises from the mixing of scalar and photon modes in the magnetic field of the neutron star which extract energy from the rotating magnetosphere.
Gr@v warmly congratulates the Event Horizon Telescope collaboration for the first direct image of a black hole. This discovery has had a worldwide impact, including news coverage in Portugal with the contribution of Gr@v and former Gr@v members.
In a recent paper "Spontaneous scalarisation of charged black holes: coupling dependence and dynamical features", [arXiv:1902.05079], by Gr@v members A. Pombo and E. Radu, in collaboration with a group at IST-Lisbon (P. Fernandes, C. Herdeiro and N. Sanchis-Gual), fully non-linear evolutions of the process of spontaneous scalarisation of charged black holes.
Gr@v member Valério Ribeiro was part of an international team of researchers studying thermonuclear eruptions in the Andromeda galaxy. The team published, in Nature magazine, the discovery of a super-nova remnant which is bigger than most supernova remnants. They found that the super-nova remnant was the consequence of yearly repeated eruptions over millions of years. Few of these systems are known in the galaxy due to the fact that we suffer from dust obscuration.
Gr@v member João Rosa was one of the recipients of the 2018 Alberto prize, awarded by the Portuguese Society of Relativity and Gravitation (SPRG). The prize was given for his work on the phenomenon of superradiance and its physical and astrophysical implications. The prize was shared by Richard Brito, a researcher of the Max Planck Institute for Gravitational Physics, in Berlin, Germany. The prize was delivered at the General Assembly of the SPRG, on 19th December 2018, during the XI Black Holes Workshop.
Gr@v member Pedro Cunha was one of the invited lecturers of the V Amazonia Workshop on Black Holes and Analogue Models of Gravity, that took place at the Federal University of Pará, in Belém, Brazil, from December 3rd to 7th, 2018. Cunha gave five lectures on "Geodesics and Shadows of Kerr black holes".
The Brazilian Funding Agency, CAPES, presented Carolina Benone's PhD Thesis with an Honorable Mention. This award results from a Brazilian national contest for the PhD theses defended in 2017. Carolina's thesis was supervised by Professor Luis Carlos Crispino from Universidade Federal do Pará (UFPA), Brazil, and includes research performed with Gr@v members, as a result of two long term visits of Carolina's to Gr@v during her PhD. Hearty congratulations Carolina!
From October 2018 onwards, Carlos Herdeiro, one of Gr@v's founding members, became an Associate Professor at the Physics Department of IST-Lisbon. The photo shows group members and Yves Brihaye, visiting from Mons University, enjoying a wonderful "parrilhada de peixe", by the seaside, a few kilometers from the Aveiro Campus, on September 28th 2018.