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Cosmology has entered an era of unprecedented precision, with an abundance of high-quality observational data. However, the increasing accuracy of measurements has unveiled tensions among different cosmological probes, potentially hinting at new physics or systematic uncertainties. In this talk, we present a powerful model-independent approach to look for new physics and systematics in the measurements.
In the first part of my talk, I will focus on the most recent measurements of the cosmic microwave background (CMB) by the Planck, ACT, and SPT collaborations. We will explore the internal consistency of the different CMB experiments and show that despite the overall agreement with the standard model predictions, there are still some indications of mild discrepancies between them. I will summarize some of the main findings in our non-parametric analysis, and discuss some implications for model building.
In the second part of my talk, I will forecast the upcoming surveys’ capability to reconstruct the time-dependence of the phenomenological functions that describe the departures from 𝚲CDM, in a data-driven manner. We use forward-modeling and Gaussian Processes to jointly reconstruct the Universe’s growth and expansion histories and show that, in General Relativity, stage-IV surveys can successfully distinguish various dark energy models from 𝚲CDM with high significance. In addition, we show that forthcoming surveys such as DESI can also detect deviations from general relativity if the dark energy behavior is accurately determined. I will also show how incorrectly assuming a 𝚲CDM expansion history naturally leads to severely biased inferences of the matter density and amplitude of fluctuations today.