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Colloque national Action Dark Energy 2021 - 5ème édition

Oct 13 – 14, 2021
Institut Henri Poincaré
Europe/Paris timezone

Contacts

Contribution List

44 out of 44 displayed
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  1. 1. Welcome / Accueil
    Alain Blanchard (IRAP , OMP)
    10/13/21, 10:10 AM
  2. 2. Fundamental constants, gravity and dark energy
    Jean-Philippe Uzan (IAP / CNRS)
    10/13/21, 10:20 AM
    Invité
  3. 46. Planck constraints on the tensor-to-scalar ratio
    Matthieu Tristram (IJClab, CNRS, France)
    10/13/21, 11:00 AM
    Contribué
    Contributions
  4. 18. Prédictions de performances de l'analyse combinée Euclid et CMB
    Dr Stéphane Ilic (Observatoire de Paris - LERMA)
    10/13/21, 11:30 AM
    Invité

    Grâce aux mesures de lentillage gravitationnel et de clustering des galaxies, Euclid posera des contraintes sans précédent sur l'Univers récent. D'autre part, des observations CMB de haute qualité (Planck et futures expériences) sont capables d'imposer des contraintes strictes sur l'Univers primordial. La combinaison de ces deux sources d'informations cosmologiques peut constituer un bras de...

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  5. 4. Dark Energy direct detection in space: MICROSCOPE and beyond
    Joel Bergé (ONERA)
    10/13/21, 2:30 PM
    Invité
  6. 26. Scale-dependence in DHOST inflation
    Andrei Lazanu (École Normale Supérieure)
    10/13/21, 3:10 PM
    Contribué
    Contributions
  7. 27. Flat rotation curves, MOND-like behavior, and CMB spectrum in the Dirac-Milne universe
    Gabriel Chardin (CSNSM Orsay)
    10/13/21, 3:30 PM
    Contribué
    Contributions
  8. 28. Mesure des fluctuations du monopole du fond diffus cosmologique
    Calum Murray (LPSC)
    10/13/21, 3:50 PM
    Contribué
    Contributions
  9. 29. Y-a-t-il une tension avec les amas?
    Alain Blanchard (IRAP , OMP)
    10/13/21, 4:10 PM
    Contribué
    Contributions
  10. 6. Dark Energy Survey Year 3 cosmology results
    Dr Agnès FERTÉ (JPL)
    10/13/21, 5:00 PM
    Invité
  11. 39. Weak lensing cluster masses and mass-richness relation in DESC DC2 simulations
    Constantin Payerne (LPSC (IN2P3))
    10/13/21, 5:40 PM
    Contribué
    Contributions

    Constraining the mass-observable relations is a key ingredient for cluster cosmology. In particular, for optical surveys such as the Rubin LSST, the cluster abundance relies on the determination of the mass-richness relation. In that context, weak gravitational lensing by galaxy clusters can be used as a powerful tool to estimate cluster masses. We use the cluster-galaxy weak lensing in the...

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  12. 5. Champs scalaires et matière noire
    Aurelien Hees (SYRTE - Observatoire de Paris)
    10/14/21, 9:15 AM
    Invité
  13. 38. A 'variable' gravitational constant and consequence on cosmology.
    Ziad Sakr (IRAP : Institut de Recherche en Astrophysique et Planétologie)
    10/14/21, 9:55 AM
    Contribué
    Contributions
  14. 31. The cosmological constant as a classical eigenvalue
    Giovanni Manfredi (CNRS)
    10/14/21, 10:10 AM
    Contribué
    Contributions
  15. 45. Rotating Inflation
    Kenza ZEGHARI (Université Pierre et Marie Curie, Paris 6)
    10/14/21, 10:25 AM

    We study Bianchi cosmologies coupled to a matter source that has the field theoretical description of a solid. Models
    of solid inflation are known for not being very efficient in diluting away anisotropy. While confirming this fact, our study finds another potential feature of Solid inflation, namely a ``rotation” of the principal axes of the expansion.
    Such a rotation is not just a ...

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  16. 35. DESI Survey Validation
    Christophe Yeche (CEA Irfu/SPP)
    10/14/21, 10:40 AM
    Contribué
    Contributions
  17. 12. On the Hubble tension and primordial magnetic fields
    Dr Karsten Jedamzik (LUPM)
    10/14/21, 11:30 AM
    Invité
  18. 33. (g-2) of the muon and screened modified gravity
    Philippe Brax (IPHT Saclay)
    10/14/21, 12:00 PM
    Contribué
    Contributions
  19. 34. Dark Gravity confronted with SN, BAO and the CMB
    Frederic Henry-Couannier
    10/14/21, 12:15 PM
    Contribué
    Contributions
  20. 7. Measurement of full-shape cosmology from the galaxy two-point clustering of DESI samples
    Pauline Zarrouk (LPNHE)
    10/14/21, 2:30 PM
  21. 32. On the impact of lensing magnification on galaxy clustering analysis
    Michel-Andrès Breton (Laboratoire d'Astrophysique de Marseille)
    10/14/21, 3:10 PM
    Contribué
    Contributions
  22. 36. Non-ideal self gravity and cosmology: a possible solution to the dark mass and energy problems within the Newtonian limit?
    Pascal Tremblin (CEA Paris-Saclay)
    10/14/21, 3:40 PM
    Contribué
    Contributions
  23. 37. Can dark energy emerge from a varying G and spacetime geometry?
    Ekim Taylan Hanimeli
    10/14/21, 4:00 PM
    Contribué
    Contributions
  24. 43. Glimmers of a post Geometric Perspective.
    Federico Piazza (CPT, Marseille)
    10/14/21, 4:15 PM
    Contribué
    Contributions

    Quantum gravitational effects are usually associated with the Planck scale but they could also become important at low energy if the wavefunction of the metric field fails to be peaked around a classical configuration.
    I try to understand such deviations from classicality within canonical quantum gravity by introducing a "fluid of observers" in the low energy theory and defining a distance...

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  25. 14. (g-2) of the muon and screened modified gravity
    philippe brax (IPHT Saclay)
    Contribué

    The Fermilab measurement of the anomalous magnetic moment of muons seems to be at odds with the standard model of particle physics. Coupled scalar fields such as the chameleon or the symmetron, which modify gravity locally, could account for the discrepancy.

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  26. 25. A 'variable' gravitational constant and consequence on cosmology.
    ziad sakr (IRAP : Institut de Recherche en Astrophysique et Planétologie)
    Contribué

    Constraints on the cosmological concordance model parameters are usually obtained using the locally measured value of the gravitational constant G. Here we relax this assumption and determine the impact of such hypothesis on the physics involved in the prediction of the cosmological observables. Using the latest CMB temperature and polarization correlations data and distance measurements from...

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  27. 30. A 'variable' gravitational constant and consequence on cosmology.
    ziad sakr (IRAP : Institut de Recherche en Astrophysique et Planétologie)
    Contribué
    Contributions
  28. 17. Are classification metrics good proxies for science output?
    Dr Emille Ishida (LPC-UCA)
    Contribué

    Population-level transient studies dependent on light curve classifiers often use classification performance as a proxy for metrics of the physical parameters of interest. This strategy allows a complete separation between the relatively straightforward classification stage and the more computationally intensive science analysis, meaning that design decisions for each are made independently of...

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  29. 23. Can dark energy emerge from a varying G and spacetime geometry?
    Ekim Taylan Hanimeli
    Contribué

    The accelerated expansion of the Universe implies the existence of an energy contribution known as dark energy. Associated with the cosmological constant in the standard model of cosmology, the nature of this dark energy is still unknown. In this talk I will discuss an alternative gravity model in which this dark energy contribution emerges naturally, as a result of allowing for a...

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  30. 8. Contributions TBD
    Contribué
  31. 13. Contributions TBD
    contributions
  32. 21. Dark Gravity confronted with SN, BAO and the CMB
    Dr frederic henry-couannier
    Contribué

    Dark Gravity is a natural extension of general relativity in presence of a flat non dynamical background. Matter and radiation fields from its dark sector,
    as soon as their gravity dominates over our side fields gravity, produce a constant acceleration law of the scale factor. After a brief reminder of the Dark Gravity theory foundations, the confrontation with the main cosmological probes...

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  33. 15. DESI Survey Validation
    Christophe Yeche (CEA Irfu/SPP)
    Contribué

    DESI est un relevé spectroscopiques de 35 millions de galaxies et de quasars réalisé sur un télescope de 4m à Kitt Peak (Arizona). Le but est d'étudier les BAO et les RSD pour des redshifts de 0. à 3.5. Le projet durera 5 ans. Il vient de terminer en mai 2021 le relevé de validation et de commencer les observations du relevé principal.
    L'objectif de cette présentation est de montrer les...

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  34. 11. Flat rotation curves, MOND-like behavior, and CMB spectrum in the Dirac-Milne universe
    Gabriel Chardin (CSNSM Orsay)
    Contribué

    The Dirac-Milne (D-M) universe, a symmetric matter-antimatter universe, i.e. with equal quantities of matter and antimatter, but where antimatter behaves as a negative mass component repulsing both matter and itself (see G. Manfredi et al., Phys. Rev. D 98, 023514 (2018) for a precise definition) presents several concordance properties with our universe (age, luminosity distance,...

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  35. 42. Glimmers of a post Geometric Perspective.
    federico piazza (CPT, Marseille)
    Contribué
    Contributions

    Quantum gravitational effects are usually associated with the Planck scale but they could also become important at low energy if the wavefunction of the metric field fails to be peaked around a classical configuration.
    I try to understand such deviations from classicality within canonical quantum gravity by introducing a "fluid of observers" in the low energy theory and defining a distance...

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  36. 20. Mesure des fluctuations du monopole du fond diffus cosmologique
    Calum Murray (LPSC)
    Contribué

    Les raies d'absorption moléculaire de quasars distants et l'effet Sunyaez-Zel'dovich thermique permettent de mesurer le monopole du fond diffus cosmologique (CMB) à différents endroits et époques de l'univers. Cette mesure permettrait notamment de contraindre les fluctuations de la densité d'énergie de radiation. Chacune de ces méthodes a des caractéristiques propres qui seront décrites dans...

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  37. 10. Non-ideal self gravity and cosmology: a possible solution to the dark mass and energy problems within the Newtonian limit?
    Pascal Tremblin (CEA Paris-Saclay)

    Inspired by the statistical mechanics of an ensemble of interacting particles (BBGKY hierarchy), we propose to account for small-scale inhomogeneities in self-gravitating astrophysical fluids by using a non-ideal Virial theorem and non-ideal Navier-Stockes equations that involve the pair radial distribution function (similar to the correlation function), as for the interaction energy and...

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  38. 16. On the impact of lensing magnification on galaxy clustering analysis
    Michel-Andrès Breton (Laboratoire d'Astrophysique de Marseille)
    Contribué

    In this talk I will discuss about the impact of magnification bias on the determination of the growth rate from redshift-space clustering. We use a the RayGal suite of $N$-body simulations that accounts for the fully non-linear structure formation and perform realistic galaxy clustering analyses, similarly as in observations, in different regime of magnification bias. We investigate a minimal...

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  39. 9. Planck constraints on the tensor-to-scalar ratio
    Matthieu Tristram (IJClab, CNRS, France)
    Contribué

    I will present constraints on the tensor-to-scalar ratio r using Planck data as described in [Tristram et al., A&A, 647, A128 (2021)].
    In this paper, we use the latest release of Planck maps (PR4), processed with the NPIPE code, which produces calibrated frequency maps in temperature and polarisation for all Planck channels from 30 GHz to 857 GHz using the same pipeline. We computed...

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  40. 24. Scale-dependence in DHOST inflation
    Dr Andrei Lazanu (École Normale Supérieure)
    Contribué

    We study the inflationary consequences of Degenerate Higher Order Scalar Tensor (DHOST) theories in a de Sitter background. We perturb the de Sitter background by operators breaking either the degeneracy condition, i.e scordatura DHOST, or the shift symmetry in the scalar field. We first consider derivative scordatura and find that in all cases the power spectra of curvature perturbations are...

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  41. 3. TBD
    philippe brax (IPHT Saclay)
    Invité
  42. 22. The cosmological constant as a classical eigenvalue
    Giovanni Manfredi (CNRS)
    Contribué

    We propose to recast Einstein's field equations as a nonlinear eigenvalue problem, where the cosmological constant $\Lambda$ plays the role of the (smallest) eigenvalue. This mathematical interpretation is fully worked out for a simple classical model of scalar gravity. The essential ingredient for the feasibility of this approach is that the classical field equations be nonlinear, i.e., that...

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  43. 40. un GDR cosmologie?
  44. 19. Y-a-t il une tension avec les amas ?
    ALAIN BLANCHARD (IRAP , OMP)
    Contribué

    Les mesures des fluctuations du fond diffus cosmologique (CMB) par Planck permettent de contraindre l'amplitude des fluctuations de la matière au décalage vers le rouge à $z \sim 1100$ dans le modèle $\Lambda$CDM, et donc de l'amplitude actuelle $\sigma_8$. D'autre part, l'abondance des amas Sunyaev-Zeldovich (SZ) détectés par Planck, avec des masses déduites sous l'hypothèse d'équilibre...

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