The universe has gone through two phases of accelerated expansion: a primordial phase called cosmic inflation and an ongoing phase that has been taking place for the last 6 billions years.
To explore cosmic inflation, we are now on the hunt for the primordial cosmic microwave background (CMB) B-modes. This signal is expected to be tenuous so we need to characterize and understand the different sources of CMB B-modes beyond cosmic inflation. In the first part of this talk, I will highlight results from Lemarchand et al, submitted to A&A, 2018 and my ongoing work addressing one astrophysical effect: Faraday rotation from magnetic field in clusters. I will explain this phenomenon and show results of its impact on CMB B-modes.
In the second part of my talk I will focus on understanding the origin of the ongoing cosmic acceleration. Observations are indeed showing that the universe is currently going through a phase of accelerated expansion. Different explanations for this acceleration are possible. One possiblity is that general relativity does not correctly describe the laws of gravity on cosmological scales. I have been interested in doing tests of gravity using cosmological observables of the growth of structure and especially weak gravitational lensing. I will first give a general introduction to the problem of cosmic acceleration and its observables. I will then present the results from Ferté et al, to appear in PRD constraining deviations to general relativity using available data sets, in addition to forecasts of these constraints with future experiments. I will end presenting a similar analysis and results I have been involved in using the first year of observation of the Dark Energy Survey. I will also highlight constrains on extensions to the standard model of cosmology from this work.
Speaker: Agnes Ferte, Jet Propulsion Laboratory
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