State of the Universe

LCDM extensions and consequences on cosmological observables and parameters constraints from current and upcoming surveys.

by Dr. Ziad Sakr (IRAP, Toulouse)

Friday, June 11, 2021 from to (Asia/Kolkata)
at Zoom
The standard cosmological LCDM model success in accommodating for most of nowadays observations, still leaves some room for further extensions, albeit with small deviations, that are awaiting upcoming surveys, to be ruled out or to be further constrained. Moreover, two main growing tensions, the measurements of the matter fluctuation parameter known as sigma 8 and that of the expansion Hubble parameter, showing discrepancies among values constrained using local versus deeper probes, are hinting for the need for exploring alternatives to LCDM model. I will review some of the phenomenologically most common proposed extensions, per se or as solutions to the aforementioned tensions, such as dark energy different from the cosmological constant, a growth index from modified gravity or massive neutrinos, and express observables within these frameworks to test their ability to fix these discrepancies with current data or forecast on constraints from future new generation surveys. I will then reiterate the previous exercise with other models, such as modifying some of the dark matter properties or supposing a dynamical gravitational constant, an additional curvature-like component, or other modified gravity models such as f(R). I will finish with a more radical modification to LCDM with models that relax the Copernican principle and with it the homogeneity and isotropy hypothesis we usually assume when performing cosmological calculations and show constraints on related null tests from current and future datasets.