21-cm line Anomaly: A brief Status

Understand

In this short review I present the status of the global 21-cm signal detected by EDGES in March 2018.

• It is organized in three parts.
• First, I present the EDGES experiment and the fitting procedure used by the collaboration to extract the tiny 21-cm signal from large foregrounds of galactic synchrotron emission.
• Then, I review the physics behind the global 21-cm signature and I explain why the measured absorption feature is anomalous with respect to the predictions from standard astrophysics.