In a paper published in Phys. Rev. Lett, Gr@v member Nico Sanchis-Gual and co-authors reports a degeneracy between the gravitational-wave signals emitted in quasi-circular precessing black-hole mergers and those from extremely eccentric mergers, namely head-on collisions.
The ability to model the evolution of compact binaries from the inspiral to coalescence is central to gravitational wave astronomy. Current waveform catalogues are built from vacuum binary black hole models, by evolving Einstein equations numerically and complementing them with knowledge from slow-motion expansions.
A call for a 2 years research position in Strong Gravity. within the research grant “Testing the Kerr hypothesis with gravitational waves and lensing", PTDC/FIS-AST/3041/2020, is open. The call closes on June 14th 2021.
Abstract: Quantifying the evidence for horizons and understanding the nature of the dark ultracompact objects that populate our Universe are some of the most pressing problems in gravitational physics.
In this work, we study the relation of the eikonal quasinormal modes (EQNMs) and the unstable fundamental photon orbits (UFPOs) in the Kerr-Newman spacetime. We find that in the eikonal limit the gravitational and electromagnetic perturbations of the Kerr-Newman black hole are naturally decoupled, and a single one-dimensional Schrodinger-like equation encoding the QNM spectrum can be derived.
Despite of the weak couplings to normal matter, light axion fields can be significantly sourced by neutron stars, leaving potentially detectable signals in gravitational waves from binary neutron star inspirals. In this talk, I am going to talk about how the axions affect the inspiral waveform, and to report a recent search for such axions with GW170817.
Abstract: The detection of gravitational waves from extreme-mass-ratio inspirals (EMRIs) with upcoming space-borne detectors will allow for unprecedented tests of general relativity in the strong-field regime. Aside from assessing whether black holes are unequivocally described by the Kerr metric, they may place constraints on the degree of spacetime symmetry.
It was recently shown that a broad class of gravity theories allows for spontaneous scalarization of black holes, letting these objects grow “scalar hair” once certain conditions are met and to remain “bald” otherwise.
Our group coordinated the "Numerical Relativity and High Energy Physics" IRSES network (2012-2015). Here is a list of the global network meetings organized:
