Ateliers action Dark Energy 2021

24 juin 2021, 10:00 → 25 juin 2021, 18:20 Europe/Paris

lien zoom envoyé par mail

Les problématiques autour de l’énergie noire apparaissent comme essentielles dans les axes de recherche de l’INSU, de l’IN2P3, de l’INP et de l'IRFU.

La communauté française en cosmologie, avec une forte implication dans plusieurs expériences ambitieuses dont le satellite Euclid et le télescope LSST, s’est très largement mobilisée sur cette problématique.

Étant donnée la situation sanitaire, les ateliers sont encore en distanciel cette année et ont lieu sous la forme de 2 demi-journées thématiques :

• Neutrinos et Grandes structures de l'Univers
• Gravité modifiée & simulations

Le lien de connexion sera envoyé aux participant-e-s la veille.

L'action Dark Energy est soutenue par :

 

jeu. 24 juin

14:00 → 18:30 Modified gravity & simulations

14:00 Aspects non-linéaires dans le galaxy clustering pour les modèles de gravité modifiée

Orateur: Filippo Vernizzi (IPhT - CEA Saclay)

ADE_2021.pdf

14:20 Modeles semi-analytiques pour le spectre de puissance non-lineaire

Orateur: Patrick Valageas (CEA Saclay)

valag1.pdf

14:40 discussion

15:10 Effet des baryons & modification de la gravité

Orateur: Yohan Dubois (IAP Paris)

YohanDubois_AtelierDarkEnergy_final.pdf

15:40 discussion

16:10 pause

16:30 Imprints of Modified Gravity Scenarios on the Inner Structure of Massive Dark Matter Halos

Orateur: Dr Pier-Stefano Corasaniti (CNRS & Observatoire de Paris)

PSC_Atelier_Dark_Energy.pdf

16:50 Internal dark matter structure of the most massive galaxy clusters since redshift 1

The evolution of the dark matter profiles of high-mass galaxy clusters from z~1 to the present day remains poorly constrained and is a powerful test of the LambdaCDM model. Such a test requires systematic confrontations of observations of a representative sample of the Universe's most massive clusters, preferably in several redshift bins, with tailor-made numerical simulations. To date, there exist no cosmological numerical simulations with the exceptionally large volume (required to simulate the rarest, most massive clusters) and the resolution (required to resolve their structure) necessary to undertake such a project. We will present the first results from a simulation campaign aimed at producing large cosmological simulations that are 1 Gpc/h on a side and have a medium mass and spatial resolution. They are being complemented with very-high resolution zoom simulations which are progressively including the non-gravitational physics of galaxy formation such as star formation, supernova and AGN feedback. The simulations are produced using the AMR code RAMSES. The first results are based on a subset of the systems, consisting of the 25 most massive galaxy clusters at each redshift (z=1, 0.8, 0.6 and 0) to study the evolution of their internal structure, finding that their dark matter profiles within r500 are strikingly similar from z ∼ 1 to the present day, exhibiting a low dispersion of 0.15 dex, and showing little evolution with redshift in the radial logarithmic slope and scatter. They have the running power law shape typical of the NFW-type profiles, but their inner structure shows no signs of converging to an asymptotic slope. This suggests that this type of profile is already in place at z > 1 in the highest-mass haloes in the Universe, and that it remains exceptionally robust to merging activity.

Orateur: Dr Amandine Le Brun (PSL & Observatoire de Paris)

ActionDEWorkshop_24062021.pdf

17:10 Can modified gravity (partly) emulate dark matter?

Orateur: Benoit Famaey (CNRS Observatoire astronomique de Strasbourg)

famaey_actionDE_final.pdf

17:30 discussion

ven. 25 juin

14:00 → 18:20 Neutrinos et LSS

14:00 Potential role of non-standard neutrino physics on structure formation

Orateur: Prof. Julien Lesgourgues (Aachen )

21.06.25_Atelier_DE_JL.pdf

14:30 discussion

15:00 The cosmological imprint of massive neutrinos in dark matter simulations

Orateur: Julien Bel (CPT Marseille)

atelier_dark_energy_noback_JB.pdf

15:30 discussion

16:00 pause

16:20 Constraining neutrino mass using three-point mean relative velocity statistics

Velocity field provides a new avenue to constrain cosmological information, and one of the commonly used statistics is the mean radial pairwise velocity. In this talk, we consider the three-point mean relative velocity (i.e. the mean relative velocities between pairs in a triplet), and show that it is a novel probe of neutrino mass estimation. We explore the full cosmological information content of the halo mean pairwise velocities, and the mean relative velocities between halo pairs in a triplet using 22,000 simulations from the Quijote suite. We find that the mean relative velocities in a triplet allows a 1-sigma neutrino mass constraint of 0.065 eV, an order of magnitude better than the mean pairwise velocity constraint. We also introduce a new estimator based on three-point mean relative velocities, and showcase how it can constrain neutrino mass independent of sigma8 and optical depth alleviating the degeneracy with these parameters. These results illustrate the possibility of exploiting the mean three-point relative velocities for constraining the cosmological parameters accurately from future cosmic microwave background experiments and peculiar velocity surveys.

Orateur: Joseph Kuruvilla (IAS, Universite Paris-Saclay)

Kuruvilla_DE21.pdf

16:50 Constraining the total neutrino mass with the power spectrum

While neutrino oscillation experiments achieved high precision measurement on the neutrino squared mass differences, the absolute scale and hierarchy are still unknown. On the cosmology side, massive neutrino's transition from a relativistic to a non-relativistic specie leaves an imprint on the Cosmic Microwave Background (CMB) temperature power spectrum, allowing for tighter constraint on the sum of the masses. Moreover, because of their high thermal velocity dispersion, even at late times, cosmological neutrinos free stream through gravitational potential wells, provoking a damping of the CDM clustering on scales smaller than their free streaming scale. This damping will be imprinted in the galaxy power spectrum, making it a probe of choice to estimate the total neutrino mass. In this talk I will present my results on the estimation of neutrino masses with the real space power spectrum of the DEMNUni (Dark Energy and and Massive Neutrino Universe) simulations. I tested different models of the non-linear power spectrum as well as several methods to estimate the covariance matrix of this observable, to achieve accurate and precise constraints on the total neutrino mass together with other cosmological parameters.

Orateur: Sylvain Gouyou Beauchamps (CPPM)

AtelierDarkEnergy_25_06_2021.pdf

17:20 discussion