Séminaire

Scalar-vector gauge unification and quantum de Sitter geometry

We consider the massless minimally coupled scalar field in the de Sitter ambient space formalism as a gauge potential or connection field. We construct the scalar gauge theory by helping an arbitrary constant five-vector field B analogous to the standard gauge theory. The Lagrangian density of the interaction between the scalar and spinor fields is presented in this framework. The Yukawa potential can be extracted from this Lagrangian density at the null curvature limit by an appropriate choice of a constant five-vector field.

Gravitation group Seminar: Rachel Gray - Cosmology with Dark Sirens and Galaxy Catalogues

Dear all,

On Monday, October 17 at 10.00 we will be welcoming Rachel Gray (Queen Mary University of London) for the gravitation group seminar. The seminar will take place online - the zoom link can be found below.

Rachel will talk about cosmological constraints from gravitational wave dark sirens and galaxy catalogs. 

Title: 
Cosmology with Dark Sirens and Galaxy Catalogues

Abstract: 

Local sources of 100 TeV neutrinos

Multi-messenger data of high energy neutrinos by IceCube and  gamma-rays by Tibet AS-gamma show new signal at 100 TeV energies outside of Galactic plane but below 20 degrees from it. This mysterious signal challenge conventional cosmic ray models, which predict major Galactic signal from Galactic plane and no significant flux at high galactic latitudes, as seen at GeV energies by Fermi LAT telescope.

Here we show that main assumption of continues distribution of cosmic rays in Galaxy is broken at PeV energies. 

Gravitation Group Seminar: Nicola Franchini: Constraining modifications of black hole perturbation potentials near the light ring with quasinormal modes

On Monday, October 3 at 10.00 we will be welcoming Nicola Franchini (APC) for the gravitation group seminar. The seminar will take place in room 631B, (a zoom link can be found below).
Nicola will talk about the constraints from quasinormal modes on black hole perturbation potentials. 

Constraining modifications of black hole perturbation potentials near the light ring with quasinormal modes

Abstract

Theory and observational constraints in nonlocal gravity

I will present selected field theoretical aspects and Bayesian model selection studies in a particular class of modified gravity theories, so-called nonlocal gravity theories. In particular, I will focus on three nonlocal gravity models that have been proposed for explaining the late-time acceleration of the expansion of the universe and have been shown to provide a statistically equivalent fit to LCDM given recent cosmological data.

Primordial Black Holes from Inflation

Abstract:
It is now recognized that primordial black holes (PBHs) may be produced in various models of inflation in the early universe. In this talk, I review several different scenarios of PBH formation from inflation, each of which has rather distinct features. Then I discuss how these models may be observationally tested in the not-so-distant future, particularly by gravitational wave observations.
 

Gravitational lensing for dark matter explorations inside the Milky Way and for cosmological investigations

Abstract. I’ll show the analysis we perform on gravitational microlensing signatures and how we estimate gravitational microlensing parameters to obtain information about several components of the dark matter in our galaxy like free-floating planets, brown dwarfs, primordial black holes, making use of actual and future space-based telescopes: Euclid, THESEUS, Gaia, Roman, etc.

Gravitation Group Seminar: Jakub Klencki on: From massive stars through X-ray binaries to gravitational-wave sources

On Monday, September 19 at 14.00 we will be welcoming Jakub Klencki (ESO Garching and Max Planck Institute for Astrophysics Garching) for the gravitation group seminar. The seminar will take place online, (the zoom link can be found below). 

Title: From massive stars through X-ray binaries to gravitational-wave sources

Abstract: 

Gravitation Group Seminar: Francois Larrouturou: Minimalism as guideline to construct new paradigms.

Next week we will be welcoming François Larrouturou (DESY Hamburg) for the Gravitation group seminar. 
The seminar will take place in person, in room 371A-Klein (the zoom link can be found below) next Monday, July 11 at 10:00

François will give an introduction to: 

Title : Minimalism as guideline to construct new paradigms.

Abstract : 

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