S'authentifier

A journey through the theoretical universe

28–29 juin 2023
Université de Toulouse, Faculté de médecine
Fuseau horaire Europe/Paris

Contacts

Liste des Contributions

19 sur 19 affichés
Exporter en PDF
  1. 13. Introduction
    Prof. Ruth Durrer (Université de Genève)
    28/06/2023 09:20
  2. 5. A Gaussian ansatz beyond the Zeldovich approximation
    Patrick VALAGEAS (CEA Saclay)
    28/06/2023 09:40

    We present a new approach to model the gravitational dynamics of large-scale structures, where we follow the evolution of the probability distribution of the displacement field. This provides a nonperturbative scheme that goes beyond shell crossing and the truncations of the power spectra on nonlinear scales directly arise from the equations of motion. Although the density power spectrum is...

    Go to contribution page
  3. 12. Structure formation and scale-free models
    M. Michael Joyce (LPNHE)
    28/06/2023 10:40

    I will discuss some of the applications of called scale-free models to the problem of non-linear structure formation: as a tool to control the accuracy of measurements from numerical simulations, as a tool for precision testing of theoretical approaches to matter clustering, and more generally as a tool to better understand and model clustering in standard cosmological models

    Go to contribution page
  4. 19. Gravitational wave standard sirens: cosmological constraints from LVK observations and future prospects with LISA
    Danny Laghi (CNES, L2I Toulouse, CNRS/IN2P3, UT3)
    28/06/2023 11:10

    Compact binary systems that emit detectable gravitational waves, such as binary black holes and binary neutron stars, can be used as "standard sirens" to constrain cosmological parameters. This talk will review cosmological results obtained from the most recent gravitational wave observations, with a focus on the most stringent constraints produced by the LIGO-Virgo-KAGRA Collaboration, while...

    Go to contribution page
  5. 17. Measuring the anisotropic stress with future galaxy surveys
    Isaac Tutusaus (IRAP)
    28/06/2023 11:40

    Galaxy surveys provide one of the best ways to constrain the theory of gravity at cosmological scales. They can be used to constrain the two gravitational potentials encoding time, Ψ, and spatial, Φ, distortions, which are exactly equal at late time within general relativity. Hence, any small variation leading to a nonzero anisotropic stress, i.e. a difference between these potentials, would...

    Go to contribution page
  6. 7. Cosmology in Minkowski space
    Lucas Lombriser (University of Geneva)
    28/06/2023 14:30

    Theoretical and observational challenges to standard cosmology such as the cosmological constant problem and tensions between cosmological model parameters inferred from different observations motivate the development and search of new physics. A less radical approach to venturing beyond the standard model is the simple mathematical reformulation of our theoretical frameworks underlying it....

    Go to contribution page
  7. 2. LCDM is alive and well
    Prof. ALAIN BLANCHARD (IRAP , OMP)
    28/06/2023 15:00

    The LCDM is expected to face two significant "tensions", one on H0 and the other on S_8. I will discuss these two tensions to assess whether current observational data are at a sufficient level to conclude that LCDM is excluded.

    Go to contribution page
  8. 18. Two-field screening and its cosmological dynamics
    philippe brax (IPHT Saclay)
    28/06/2023 15:30

    I will present how screening could (or could not) occur in two-field models of the axio-dilaton type and
    present a simplified analysis of their cosmology.

    Go to contribution page
  9. 21. Relativistic asymmetry in galaxy-galaxy and galaxy-ellipticity correlations
    Shohei Saga (IAP)
    28/06/2023 16:00

    The observed galaxy distribution via galaxy redshift surveys appears distorted due to redshift-space distortions (RSD). One dominant contribution to RSD comes from the Doppler effect induced by the peculiar velocity of galaxies. The Doppler effect produces the even multipole anisotropy in the correlation function and it has been well studied in a few decades. I will present my recent work on...

    Go to contribution page
  10. 3. Why we need to care about unobservable modes
    Dr Fabien Lacasa (Institut d'Astrophysique Spatiale, Orsay)
    28/06/2023 17:00

    In the coming decades, large observational efforts will allow us to map the distribution of the large scale structure in the evolved Universe, a.k.a. the cosmic web. The major purpose of these efforts is to extract the cosmological information present in the observed density fluctuations. However, from observations of the Cosmic Microwave Background, we know that there are also fluctuations on...

    Go to contribution page
  11. 15. Gravitational waves from (magneto)hydrodynamic turbulence at LISA and PTA
    Chiara Caprini (APC)
    28/06/2023 17:30
  12. 11. Probing the primordial power spectrum on small scales with dark matter subhalos
    Julien Lavalle (CNRS - LUPM - Montpellier)
    29/06/2023 09:30

    I will discuss the role dark matter subhalos may play in unveiling or constraining both the nature of dark matter and the properties of the primordial power spectrum on small scales. This is a topic in which semi-analytical predictions can be made without resorting to cosmological simulations, in the regime where dark matter subhalos are too light to accrete baryons, as expected in the cold...

    Go to contribution page
  13. 10. A visual and theoretical journey into some black hole and wormhole universes
    Alain Riazuelo (CNRS - Institut d'astrophysique de Paris)
    29/06/2023 10:00

    Although it looks mathematically simple, the Schwarzschild metric describes a complicated spacetime that is endowed with two asymptotic regions and two singularities. When including electric charge and spin, other black hole metrics are even more complicated. Although causal diagrams help to figure out what an observer can possibly see, it is almost impossible to guess how different regions of...

    Go to contribution page
  14. 8. Bouncing cosmological model ambiguities
    Patrick Peter (CNRS)
    29/06/2023 11:00

    I'll present recent results showing that getting a bounce by means of quantising the background may yield to a mild ambiguity on the spectral index of the perturbations, and a more serious one on its amplitude. We trace the origin of this issue to the fact that quantising and applying a canonical transformation do not commute.

    Go to contribution page
  15. 6. Topology in the electroweak model
    Tanmay Vachaspati (Arizona State University)
    29/06/2023 11:30

    I will discuss topology in the electroweak model.

    Go to contribution page
  16. 9. Multipole Expansion of the Local Expansion Rate
    Christian MARINONI (Centre de Physique Théorique)
    29/06/2023 14:00

    The lack of convergence to a consensus value for the Hubble constant has triggered a search for the reliability of non-standard cosmological line elements. The question is whether metrics with a lower degree of symmetry than FRW, while remaining simple, provide a reliable description of the data in the local part of the universe where the global uniformity is violated. We address this problem...

    Go to contribution page
  17. 22. Relativistic cosmology in the nonlinear regime
    Dr Francesca Lepori (Zurich)
    29/06/2023 14:30

    Relativistic cosmology in the nonlinear regime

    Go to contribution page
  18. 20. Concluding remarks
    Ruth Durrer (Université de Genève)
    29/06/2023 15:40
  19. 14. Nonlinearity in relativistic cosmology of the early and late universe
    Dr Marco Bruni

    In this talk I will give a brief overview of work on three topics: 1) nonlinear perturbation theory, observables and gauge-invariance; 2) bouncing cosmology based on dark energy with a nonlinear equation of state, possibly interacting with CDM; 3) full-GR simulations of nonlinear structure formation

    Go to contribution page