CMB Anomalies and the Hubble Tension

Understand

The standard $\Lambda$CDM model of cosmology is largely successful in describing many observations, including precise measurements of the Cosmic Microwave Background (CMB) radiation.

• However, some intriguing anomalies remain currently unexplained within this theoretical framework.
• Such discrepancies can be broadly categorized into two groups: those involving CMB-independent probes and those within different CMB experiments.
• Examples of the former category include the $H_0$-tension between the value of the present-day expansion rate of the Universe inferred by CMB observations and local distance ladder measurements.