Conveners
Gravitation and Cosmology: 1
- Vyacheslav Dokuchaev ()
Gravitation and Cosmology: 2
- Elena Arbuzova (Dubna State University and Novosibirsk State University)
Gravitation and Cosmology: 3
- Sergei Bolokhov (RUDN University)
Gravitation and Cosmology: 4
- Sergey Rubin ()
Description
https://zoom.us/j/95346789951
Presentation Materials
AdS/CFT correspondence has provided a very important tool for studying
the strongly coupled dynamics in a class of superconformal field theories,
in particular, ${\cal N} = 4$ super Yang-Mills theory
and the corresponding gravity dual description in AdS space-time.
In this work, we have used time dependent AdS/CFT correspondence to
study the expansion of the strongly coupled QGP...
We generalise the anisotropic core–envelope model of the super-dense star to kappa-deformed space-time (a non-commutative space-time) and study the modifications due to the existence of a minimal length. We formulate Einstein’s field equation in the kappa-deformed space-time and solve it to obtain the anisotropic core–envelope model, describing the super-dense star, in kappa deformed...
A class of dilatonic black hole dyon-like solutions in the gravitational
$4d$ model with two scalar fields, two 2-forms and two 2-dimensional dilatonic coupling vectors is obtained. The solutions are governed by two parameters $P > 0$ and $\mu > 0$. For collinear dilatonic coupling vectors the metric of the solution is coinciding with that
of the Reissner-Nordstr\"om one. The physical...
The hybrid metric-Palatini theory of gravity (HMPG), proposed in 2012 by T. Harko et al.,
is known to successfully describe both local (solar-system) and cosmological observations.
We discuss static. spherically symmetric vacuum solutions of HMPG with the aid of its scalar-tensor
representation. This scalar-tensor theory coincides with general relativity with a conformally
coupled scalar...
It is described the motion of bright spot in jets from supermassive black holes M87 and SgrA viewed by a distant observer. It is supposed that the motion of this bright spot is ballistic. The trajectories of photons emitted by the bright spot and reaching a distant observer are calculated by using the Carter equations of motion for test particles in Kerr metric. We calculate the positions,...
We consider some properties and possible observational manifestations of very heavy primordial black holes, with mass ~10^9-10^10 solar masses. These black holes should be surrounded by dense dark matter and barionic halos even at early cosmological epochs. The gas dynamics properties of the barions provide the mechanisms as for emission of radiation and for deep absorption at the periphery of...
The existence of the ergosphere of the Kerr metric does not manifest itself in quantum equations for particles of different spins.
To justify the Penrose process with energy extraction from the ergosphere, it is necessary to substantiate and prove its existence within the framework of the consistent quantum theory.
Tidal forces near a black hole with scalar hairy
E.L. Andre, I.M. Potashov, Ju.V. Tchemarina, and A.N. Tsirulev
Faculty of Mathematics, Tver State University, 35 Sadovyi, Tver, Russia, 170002
We deal with static, asymptotically flat, spherically symmetric black holes supported by a minimally coupled scalar field with an arbitrary self-interaction potential. We consider a scalar black hole...
It is since 1966, with the paper of DeWitt, that there is great interest in the interplay between the theory of gravitation and superconductivity. In the following years, a lot of theoretical papers about this topic have been produced, until Podkletnov and Nieminem declared to have observed a gravitational shielding in a disk of YBaCuO. Of course, after the publication of this paper, other...
Euclid is an ESA medium-class mission which will launch a space telescope by the end of 2022 with the aim to perform the largest galaxy survey until now, covering up to one third of the sky and reaching unprecedented precision in probing the Dark sector of the Universe, i.e. Dark Energy and Dark Matter. Euclid will acquire the 2D images of the galaxies’ spectra with an instrument called NISP,...
Quantum liquids described by wave equations with logarithmic nonlinearity, usually referred as “logarithmic fluids”, are very instrumental in describing generic condensate-like matter [1], including strongly-interacting quantum liquids, one example being a superfluid component of He-4 [2,3]. Applications of the logarithmic fluids can also be found in a theory of physical vacuum, which is a...
We investigate inflationary dynamics in the framework of the Einstein-Gauss-Bonnet gravity using the effective potential. In the model under consideration, the inflaton field is non-minimally coupled to the Gauss-Bonnet curvature invariant, so that the latter appears to be dynamically important. We consider a quartic potential for the inflaton field, in particular the one asymptotically...
We demonstrate explicitly that in the quadratic gravity the energy-momentum tensor is automatically conservative. Thus, its non-conservation, i.e., the creation of the matter fields and particles straight from the geometry is possible only by the double layer formed on the singular hyper-surface where the curvature tensor undergoes a jump. These double layers describe the gravitational shock waves.
The conventional Friedmann cosmology is known to be in tension with the existence of stable particles having interaction strength typical for supersymmetry and heavier than several TeV. A possible way to save life of such particles may be a modification of the standard cosmological expansion law in such a way that the density of these heavy relics would be significantly reduced. We study...
Ju.V. Tchemarina, I.M. Potashov, I.A. Shapovalova, and A.N. Tsirulev
Faculty of Mathematics, Tver State University, 35 Sadovyi, Tver, Russia, 170002
We study nonstationary spherically symmetric solutions of the Einstein-scalar field system with a massless scalar field minimally coupled to gravity. We use a method for constructing nonstationary configurations of a spherically symmetric scalar...
Different cosmological scenarios are confronted with recent observational data, in particular, models with interaction of the dark components which are interpreted as scalar field with common potential, two models with bulk viscosity combined with power-law and logarithmic equations of states, F(R) models and other scenarios. The mentioned observations include the Pantheon catalog of Type Ia...
We consider a new mechanism of baryon/lepton number accumulation in the early Universe in theories with compact extra dimensions. The relaxation processes in the extra space metric lead to the establishment of symmetrical extra space configuration and take place during its formation. As a result, the initial accumulation of the charges (numbers) associated with the symmetry occurs. A variant...
Cosmic voids are the biggest large scale structure of the universe, whose evolution is
sensitive to cosmological parameters. In particular, it is possible to study their auto-
correlation function, or cross-correlate their distribution with other cosmological
observables, such as the CMB, the galaxy distribution or the weak gravitational lensing.
In this talk I will present the forecast on the...
