Why are radio telescope receivers cooled to very low temperatures?

Radio telescope receivers are cooled to very low temperatures to significantly reduce their internal noise, which is essential for achieving the best possible sensitivity when measuring extremely weak cosmic radio sources.1

This internal noise, often referred to as thermal noise or Johnson noise, is caused by the thermal agitation of free electrons within the receiver's electronic circuits and components. By cooling the solid-state amplifiers to cryogenic temperatures, engineers can minimize this noise, ensuring that the faint signals from space are not masked by the receiver's own electronic activity.21