Théorie

Black holes and the integrability of extended body dynamics

In general relativity, freely-falling test objects follow geodesics of the background spacetime in which they live. In a sense, this feature is a mere rephrasing of Einstein’s equivalence principle. In 1968, Brandon Carter showed that the geodesic motion of objects orbiting a Kerr black hole was integrable, in the sense of Hamiltonian mechanics, by discovering a fourth constant of motion that now bears his name. This “universality” of geodesic free fall is, however, but an approximation: In general, two different bodies will follow two distinct paths, depending on how they spin and deform.

Latest Results of the Diffuse Supernova Neutrino Background Search in Gadolinium-loaded Super-Kamiokande

The Diffuse Supernova Neutrino Background (DSNB) is the collection of neutrinos emitted from all past core-collapse supernovae, and it has yet to be detected experimentally. An observation of the DSNB can probe the star formation history of the universe, the fraction of black hole-forming supernovae, and even novel neutrino physics phenomena. At present, the Super-Kamiokande (SK) water Cherenkov detector is the most sensitive experiment to detect the DSNB.

Analytic Inversion of the M-R relation

The structure of neutron stars is determined by the so-called TOV equations of general relativity. Knowledge of the pressure-energy density relation is sufficient to determine the neutron star mass-radius (M-R) relation. Recent observations from X-ray telescopes, radio timing of pulsars, and gravitational wave observations, have provided several constraints on the masses and radii of neutron stars.

Late-time signal from binary black hole coalescences

Recently, studies on numerical evolutions of eccentric binary inspirals found a several orders of magnitude enhancement of the post-ringdown tail amplitude. This characteristic might render the tail a phenomenon of observational interest, opening the way to experimental verification of this general relativistic prediction in the near future. I will present an analytical perturbative model that accurately predicts the numerically observed tail evolution.

Cosmic Rays and Neutrinos in the Multi-Messenger Era

The 'Cosmic Rays  in the Multi-Messenger Era' conference aims to bring together the scientific communities working on high-energy cosmic rays, from an experimental point of view as well as from a theoretical and phenomenological sides. In addition to detailed presentations of theoretical models dealing with the production of cosmic rays and secondary neutrinos and gamma-rays, the conference will include reviews of the latest experimental results as well as prospects for the next decade.

Classical and stochastic calculations for inflationary correlators

The statistics of primordial scalar perturbations play a crucial role in providing phenomenological constraints for new inflationary models. In particular, the probability of unlikely large scalar perturbations (leading to primordial black hole formation) and the concurrent GW backgrounds are very sensitive to the tail of the PDF of primordial curvature perturbations. We analyse such tails in inflationary models featuring an ultra-slow roll phase, known to enhance both the amplitude and non-Gaussianity of curvature perturbations at small scales.

Scalar perturbations from inflationary magnetogenesis

Primordial non-Gaussianities, though yet unobserved, remain an important observable since they can help differentiate various models of inflation. This necessitates a deep understanding of the various processes that could contribute to these non-Gaussianities, with inflationary magnetogenesis being one of them. Often, the spectrum and the bispectrum of the perturbations produced during inflation are studied under the assumption that the metric perturbations can be neglected and that all the relevant physics resides in the coupling of the inflaton and the gauge fields.

Pages

Subscribe to RSS - Théorie