8 papers
Seeing Unseen Gravitational Wave Inspirals at the Galactic Center
Pau Amaro Seoane, Qimin Song, Shao-Dong Zhao +14
The Galactic Center is expected to host a population of extremely large mass-ratio inspirals (X-MRIs) migrating toward the supermassive black hole. We propose an observational appr…
Superdiffusion at the Galactic Centre
Pau Amaro Seoane, Kostas Tzanavaris, Reinhard Genzel +14
Tracking S-star cluster orbits around Sgr A* calibrates orbital transport models for space-borne gravitational wave detectors. Standard kinetic theories model this cluster via loca…
The free boundary problem in general relativity
Kostas Tzanavaris, Latham Boyle, Neil Turok
We study the action principle for space-times whose boundary is singular. We suggest that it is natural to treat the singularity as a {\it free} boundary, where the variation is un…
Perfect fluids revisited: an action principle approach
Kostas Tzanavaris
We revisit the variational principle for relativistic perfect fluids in a manifestly covariant formulation based on differential forms, with particular attention to the boundary da…
Popcorn EMRIs: Transient Gravitational Wave Signals and Their Analysis in Schwartz Space
Pau Amaro Seoane, Kostas Tzanavaris
We investigate extreme-mass ratio inspirals (EMRIs) with orbital periods exceeding the observational timescale of mHz gravitational wave observatories. In their early, highly eccen…
Black Mirrors: CPT-Symmetric Alternatives to Black Holes
Kostas Tzanavaris, Latham Boyle, Neil Turok
Einstein's equations imply that a gravitationally collapsed object forms an event horizon. But what lies on the other side of this horizon? In this paper, we question the reality o…
Mono- and oligochromatic extreme-mass ratio inspirals
Pau Amaro Seoane, Yiren Lin, Kostas Tzanavaris
The gravitational capture of a stellar-mass object by a supermassive black hole represents a unique probe of warped spacetime. The small object, typically a stellar-mass black hole…
Curvature conditions for spatial isotropy
Kostas Tzanavaris, Pau Amaro Seoane
In the context of mathematical cosmology, the study of necessary and sufficient conditions for a semi-Riemannian manifold to be a (generalised) Robertson-Walker space-time is impor…