Le contenu de cette page n’est pas disponible en français. Veuillez nous en excuser.

# Cosmology & Gravitation

This series consists of talks in the areas of Cosmology, Gravitation and Particle Physics.

## Seminar Series Events/Videos

oct 20 2020 - 11:00am
Speaker(s):
Scientific Areas:
oct 27 2020 - 11:00am
Speaker(s):
Scientific Areas:
nov 10 2020 - 11:00am
Speaker(s):
Scientific Areas:
nov 17 2020 - 11:00am
Scientific Areas:

## Strong gravitational lensing as a cosmological probe: new ways of constraining dark

Mardi oct 13, 2020
Speaker(s):

Studying the smallest self-bound dark matter structure in our Universe can yield important clues about the fundamental particle nature of dark matter, and galaxy-scale strong gravitational lensing provides a unique way to detect and characterize dark matter on small scales at cosmological distances from the Milky Way. Research in this field can be broadly separated into works that aim to directly detect individual perturbers and works that aim to statistically constrain the matter distribution by looking at collective perturbations caused by an unresolved population of perturbers.

Collection/Series:
Scientific Areas:

## Cosmology from current and future spectroscopic galaxy surveys

Mardi oct 06, 2020
Speaker(s):

Mapping of galaxy density fluctuations on large scales is one of the most important goals of observational cosmology in this decade. These observations can significantly improve our knowledge of the universe, its origins and composition. In this talk I will review some of the science goals of the ongoing and future spectroscopic galaxy surveys and explain how these goals can be met. In particular, I will focus on some recent progress in theoretical modelling of the nonlinear structure formation and show how it can be used to extract cosmology from observations of the cosmic web.

Collection/Series:
Scientific Areas:

## Search for Lensed Gravitational Waves from LIGO/Virgo Binary Black Hole Mergers: Intriguing Candidates in O2

Mardi sep 29, 2020
Speaker(s):

Current and forthcoming observing runs at ground-based laser interferometry detectors are starting to uncover gravitational waves from binary black hole (BBH) mergers at cosmological distances, and a fraction of them are expected to be gravitationally lensed by intervening galaxy or cluster lenses with multiple images. Such strongly lensed events, if discovered, may offer a precious opportunity to localize BBH host galaxies and probe global and small-scale property of the lens mass profile.

Collection/Series:
Scientific Areas:

## Halo gas thermodynamics from the cosmic microwave background: implications for large-scale structure and galaxy formation

Mardi sep 22, 2020
Speaker(s):

Understanding galaxy formation is an outstanding problem in Astrophysics. The feedback processes that drive it, 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 the largest theoretical systematics for percent precision weak lensing surveys like DES, HSC, Rubin Observatory, Roman Observatory and Euclid.

Collection/Series:
Scientific Areas:

## CMB lensing and new constraints on the early universe

Mardi sep 15, 2020
Speaker(s):

Measurements of gravitational lensing in the cosmic microwave background (CMB) allow the dark matter distribution to be mapped out to uniquely high redshifts. After giving a brief overview of current and upcoming CMB lensing measurements, I will focus on two new ways of using CMB lensing, in combination with galaxy surveys, to constrain the early universe. First, I will explore how CMB lensing and galaxy surveys could provide insights into current discrepancies in measurements of the Hubble constant.

Collection/Series:
Scientific Areas:

## Cosmology from the SDSS

Mardi juil 28, 2020
Speaker(s):

On Monday July 20th, we announced the final results from extended Baryon Oscillation Spectroscopic Survey (eBOSS), the last large-scale structure galaxy survey to be undertaken within the umbrella of the Sloan Digital Sky Survey (SDSS). This marks the culmination of 20 years of galaxy surveys undertaken using the Sloan Foundation Telescope.

Collection/Series:
Scientific Areas:

## Relieving the Hubble tension with primordial magnetic fields

Mardi juil 14, 2020
Speaker(s):

The standard cosmological model determined from the accurate cosmic microwave background measurements made by the Planck satellite implies a value of the Hubble constant H0 that is 4.2 standard deviations lower than the one determined from Type Ia supernovae. The Planck best fit model also predicts lower values of the matter density fraction Om and clustering amplitude S8 compared to those obtained from the Dark Energy Survey Year 1 data.

Collection/Series:
Scientific Areas:

## Space time fluctuations in AdS/CFT and Extensions to Minkowski

Mardi juil 07, 2020
Speaker(s):

Based on recent work arXiv:1902.08207 and arXiv:1911.02018 with E. Verlinde.

Collection/Series:
Scientific Areas:

## What’s Next for the Effective Field Theory of Large Scale Structure?

Mardi juin 30, 2020
Speaker(s):

Over the last decade, the Effective Field Theory of Large Scale Structure (EFTofLSS) has emerged as a frontrunner in the effort to produce accurate models of cosmological statistics. Quantities such as power spectra can be fit with sub-percent precision, and there is a wealth of literature applying the formalism to more complex statistics. It is interesting to ask what lies ahead for the theory. Can it be used for cosmological parameter inference? And is it just for statistics based on the 3D density field?

Collection/Series:
Scientific Areas:

## COVID-19: Detecting the Dark Matter of the Disease

Mardi juin 16, 2020
Speaker(s):

COVID-19 is a mysterious disease associated with a large number of unanswered questions.

In this talk we review what is currently known, what is still a mystery and highlight some of our recent work on the role of climate, blood type and vaccinations on the transmission of the disease and on the extent of "dark infections", the asymptomatic and untested proportion of infections. We end with a list of open research questions that may be amenable to techniques from physics and data science.

Collection/Series:
Scientific Areas:

Speaker: