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ALAIN BLANCHARD (IRAP , OMP)13/10/2020 10:45
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Jean-Paul Kneib (LAM)13/10/2020 11:00
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ALAIN BLANCHARD (IRAP , OMP)13/10/2020 11:50
La possibilité que la constante de gravitation évolue dans le temps est une éventualité qui a été explorée par le passé. Je présenterais quelques résultats récents sur cette possibilité en Cosmologie et la façon dont cela peut être une alternative au modèle standard.
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Isaac Tutusaus (ICE/IRAP)13/10/2020 12:15
The future large galaxy surveys will allow for precise cosmological analyses using the clustering of galaxies and cosmic shear. The cross-correlation between these probes can tighten constraints and it is therefore important to quantify its impact for future surveys. In this talk I will present the latest results of the Euclid Collaboration quantifying the role of the cross-correlation between...
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Nicolas Chartier (LPENS)13/10/2020 12:40
To exploit the power of next-generation large-scale structure surveys, ensembles of numerical simulations are necessary to give accurate theoretical predictions of the statistics of observables. High-fidelity simulations come at a towering computational cost. Therefore, approximate but fast simulations, surrogates, are widely used to gain speed at the price of introducing model error. We...
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Eric Aubourg (APC)13/10/2020 14:30
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Alexandre Barthelemy (IAP)13/10/2020 15:20
I will present a theoretical description of the weak-lensing Aperture-mass field with large deviation theory. I will highlight the difficulty I encountered comparing the formalism to ray-tracing numerical simulations and emphasize the need for accurate tests of non gaussian statistics in such numerical suites if we are to correctly use them in future large surveys.
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Prof. Norma G. Sanchez (CNRS LERMA PSL OP SU Paris)13/10/2020 15:45
Du Vide trans-Planckian à l'Energie Noire dans le Modele Standard de l'Univers
Le Résummé sera envoyé plus tard pour inclure plus des résultats récents
Merci pour votre comprehension !
A bientot et bien amicalement à vous,
NS
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Shohei Saga (Observatoire de Paris, LUTh)13/10/2020 16:30
The observed galaxy distribution via galaxy redshift surveys appears distorted due to redshift-space distortions (RSD). While one dominant contribution to RSD comes from the Doppler effect induced by the peculiar velocity of galaxies, the relativistic effects, including the gravitational redshift effect, are recently recognized to give small but important contributions. Such contributions lead...
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Florent Leclercq (Imperial College London)13/10/2020 16:55
I will first introduce a new, perfectly parallel approach to simulate cosmic structure formation, based on the spatial COmoving Lagrangian Acceleration (sCOLA) framework. Building upon a hybrid analytical and numerical description of particles' trajectories, sCOLA allows an efficient tiling of a cosmological volume, where the dynamics within each tile is computed independently. I will show...
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Dr Emmanuel Schaan (LBNL)13/10/2020 17:20
The feedback mechanisms that regulate galaxy formation, exploding stars and accretion onto supermassive black holes, are poorly understood. This results in an order unity uncertainty in the distribution of the gas inside halos, the ``missing baryon problem''. Because baryons are 15% of the total mass in the universe, this baryonic uncertainty is also the largest theoretical systematics for...
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Prof. Jeremy Sakstein (University of Hawai'i )14/10/2020 09:00
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Pierros Ntelis (CPPM)14/10/2020 09:50
Euclid is going to reveal the exciting nature of our universe by observing Emission Line Galaxies (ELG) in the redshift region 1 < z < 2, with a high survey area of 15000 deg2. In this talk, I will describe the Systematic Effect of the Line-Misidentification, an important effect of Spectrophotometric observations on high contaminated galaxy samples from interlopers. Then, I will present its...
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Richard Neveux (CEA Saclay)14/10/2020 10:15
I will present the clustering analysis of quasars of the final data release (DR16) of eBOSS. The sample contains $343\,708$ quasars between redshifts $0.8\leq z\leq2.2$ over $4699\,\mathrm{deg}^2$. We calculate the Legendre multipoles (0,2,4) of the anisotropic power spectrum and perform a BAO and a Full-Shape (FS) analysis at the effective redshift $z{\rm eff}=1.480$. The errors include...
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Corentin Ravoux14/10/2020 11:00
The Lyman-$\alpha$ forest, observed at optical wavelength, is a probe of large-scale matter density fluctuations at redshift higher than 2.1. It consists of absorptions in the electromagnetic spectrum of bright and distant sources such as quasars, due to the Lyman-$\alpha$ transition of intervening neutral hydrogen located along their lines-of-sight. As such, it provides a measurement of the...
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Pierre Fleury (Instituto de Física Teórica UAM/CSIC)14/10/2020 11:50
Mergers of compact objects have been nicknamed standard sirens, by analogy with electromagnetic standard candles, because their waveform directly gives access to their distance. When an electromagnetic counterpart is observed, such sources thus allow us to construct a Hubble diagram, just as supernovae. Recently, the gravitational-wave Hubble diagram has been argued to be a key probe of...
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Florian Ruppin (LPSC)14/10/2020 12:15
Upcoming optical/IR surveys will have both the sensitivity and the area to push cluster detection to $z > 2$. The $Euclid$ and LSST cluster catalogs will contain of the order of $100,000$ cluster detections, which is two orders of magnitudes more than the number of clusters detected by $Planck$. As the largest gravitationally bound systems in the universe, galaxy clusters provide a...
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Jean-Eric Campagne (LAL-IN2P3-CNRS and Univ. Paris 11)14/10/2020 12:40
Mise en évidence de perturbations adversaires d'un modèle de CNN pour le photo-z, recherche de robustesse.
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14/10/2020 14:30
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Tristan Blaineau (LAL)14/10/2020 16:30
Pour estimer l'efficacité d'une analyse de recherche de microlentilles gravitationnelles, il est nécessaire de connaître le nombre de sources réellement observées. En effet une source identifiée peut être composée de plusieurs étoiles qui n'ont pu être séparées par l'instrument (blending). Ces étoiles peuvent être proches le long de la ligne de visée par le fait du simple hasard ou elles...
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Dr Alice Pisani (Princeton University)14/10/2020 16:55
In this talk I present novel cosmological constraints obtained from cosmic voids in the final BOSS DR12 dataset. I briefly introduce voids as a tool for cosmology, and focus on illustrating how to get constraints from the void-galaxy cross-correlation function, relying on measurements of the Alcock-Paczynski effect and of the redshift-space distortions pattern around voids. I discuss...
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Dr Olivier Doré (JPL)14/10/2020 17:20
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Solène Chabanier15/10/2020 09:00
Given the increasing supercomputing power that comes along with increasing precision of the next generation cosmological surveys, numerical simulations appear to be an ideal tool to reach the targeted percent accuracy of future measurements.
In this talk, I will present the interest of numerical simulations for observational cosmology.Measurements will reach the precent-level accuracy...
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Anais Moller (CNRS / LPC Clermont)15/10/2020 09:50
Next generation experiments such as the Vera Rubin Observatory Legacy Survey of Space and Time (LSST) will provide an unprecedented volume of time-domain data opening a new era of optical big data in astronomy. To fully harness the power of these surveys, new methods must be developed to deal with large data volumes and to coordinate resources for follow-up of promising candidates. In this...
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Alex Smith (IRFU, CEA Saclay)15/10/2020 10:15
The two-point clustering analysis of the eBOSS DR16 QSO sample provides our best cosmological measurements at an effective redshift z ~ 1.5. As part of the final analysis, we performed an N-body mock challenge using HOD mocks constructed from the OuterRim simulation. The aim of this was to validate the RSD models used in the analysis, and to measure the modelling systematic uncertainties. This...
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Nicolas Martinet (LAM/CNES)15/10/2020 11:00
I will present some results from the past 2-3 years of cosmic shear analyses. Current surveys (KiDS, DES, HSC) focus on understanding the recent tension on the structure growth parameter S8 found between the CMB and the weak-lensing probes. This is done by testing cosmological models beyond Lambda CDM, carefully studying every possible systematic bias, and re-analyzing and combining the...
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Sylvie Dagoret-Campagne (LAL)15/10/2020 11:50
Preliminary
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Next generation of large cosmological survey with a huge (10^9-10^10) statistics of sources (Galaxy, Clusters and Supernova) requires sub-percent photometric accuracy or better to improve systematic errors at similar level of the statistical errors on cosmological parameters.
Ground observatories are very sensitive to atmospheric conditions due to the fluctuations on clouds... -
Florian Kéruzoré (LPSC)15/10/2020 12:25
As the largest and most massive gravitationally bound objects in the universe, galaxy clusters are excellent tracers of cosmic structures evolution, and can therefore be used to probe the underlying cosmological parameters. In order to do so, a careful understanding of the systematic effects involved in the cosmological exploitation of cluster surveys is crucial. One source of such systematic...
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Ludovic Montier (IRAP)15/10/2020 14:30
Cosmological inflation is the leading hypothesis to resolve the problems in the Big Bang theory, predicting that primordial gravitational waves were created during the inflationary era, which then imprinted large-scale curl patterns in the cosmic microwave background (CMB) polarization map, called the B-modes. Measurements of the CMB B-mode signals are known as the best probe to detect the...
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