Institute for Advanced Study/Princeton University Early Universe/Cosmology Lunch Discussion

Topic 1: In this talk, I present the impact of general relativistic effects on the galaxy power spectrum. After introducing the full general relativistic expression for the galaxy number density, I define the theory power spectrum and describe its relation to observations. Then, I discuss the issue of infrared divergence, as general relativistic effects have previously been believed to cause a divergent signal contaminating the measurement of primordial non-Gaussianity. I show that there is, in fact, no infrared divergence, as this unphysical behaviour vanishes when accounting for all general relativistic effects consistently. Finally, I present our numerical computation of the full galaxy power spectrum, showing the deviations from the standard prediction caused by the presence of non-divergent terms from relativistic corrections. I conclude that, as relativistic effects lead to significant corrections at low k, they need to be taken into account in the analysis of large-scale data.

Topic 2: In order to maximize the scientific return of cosmological surveys we need an estimator that extracts all information from the field while marginalizing over uncertain baryonic effects. In this talk I will show how neural networks can find that estimator.