Constraints on dark energy from eBOSS lyman-alpha data

The discovery of the accelerated expansion of the Universe was a surprise and remains a mystery. Is it due to a yet misunderstood theory of gravity or fueled by the perplexing dark energy? The BOSS/eBOSS survey is a state-of-the-art experimental effort to shed light on the matter. The PhD candidate will work in the context of the BOSS/eBOSS international collaboration. She/he will use lyman-alpha data to extract the highest-redshift most precise measurements of the Hubble expansion rate and the angular diameter distance to constrain the history of the expansion rate.

Theory and observations of the 21cm line at large redshift

Radio astronomy is undergoing a period of rapid advances because of digital techniques that allow an improvement in sensitivity of several orders of magnitude. The universe nearby and the initial conditions of the universe have now been characterized at great precision thanks to modern galaxy surveys and precision measurements of the cosmic microwave background. But the intermediate epoch, sometimes dubbed the “Dark Ages,” remains largely unexplored. However precision measurements using the 21cm line will allow a detailed three-dimensional characterization of this intermediate epoch.

Zodiacal Emission from Planck, COBE, IRAS and other Satellites

Zodiacal Emission is the emission of infrared radiation by heated particles in our Solar System. The full-sky Zodiacal emission was first mapped over the full-sky by the IRAS satellite, but it has now been detected by COBE, Planck, WISE, and Akari, among others. There has, however, never been an analysis which combined all these experiments. In addition, many earlier analyses were done with computers that are much less powerful than those to which we have access today.

Zooming on B-modes: data analysis and scientific exploitation of current and future data sets of POLARBEAR/Simons Array - next generation CMB B-mode observatory

POLARBEAR (PB) was the first experiment deployed as part of this program and delivered in the last couple of years some of the most interesting results in the field. This single-telescope, single-frequency observatory operating with O(1000) high-sensitivity detectors is going to be progressively replaced by a more powerful Simons Array (SA), composed of three telescopes, observing in at least three frequency bands and furnished with roughly O(10,000) detectors.

Probing Dark Energy and Modified Gravity with Galaxy Clusters with Euclid

The primary objective of cosmological research in the coming decade is to understand the accelerated expansion of the Universe. Is it caused by a new cosmic component commonly called dark energy or a modification to General Relativity? The abundance of galaxy clusters as a function of their mass and its evolution with redshift is a sensitive probe of the expansion rate and of structure formation. Detecting and counting clusters is therefore an observational method probe of both dark energy and of possible modifications to General Relativity.

LABORATOIRE

ASTROPARTICULE & COSMOLOGIE

Cosmologie