Cosmological anomalies shedding light on the dark sector

Despite the remarkable success of the ΛCDM model of cosmology, several tensions have emerged in recent years. The most well-known example is the 4-5\sigma discrepancy between the value of the Hubble constant H0 measured with the local distance ladder and the one inferred using the cosmic microwave background (CMB).  Another longstanding anomaly is the 2-3\sigma mismatch between the weak gravitational lensing and CMB determinations of the amplitude of matter fluctuations on 8 Mpc/h scales, typically parameterized as S8 ≡σ8(Ωm/0.3)^0.5. In this talk, I discuss how the aforementioned tensions could be giving us hints about the properties of the dark sector in the universe. In particular, I’ll argue that the H0 and S8 tensions can be respectively explained by a dark energy component in the early universe and a scenario of 2-body decaying dark matter. I will finally show how it is possible to quantify the relative success of 16 different models that have been proposed to resolve the H0 tension, by using a series of metrics and a vast array of data combinations.