If the CMB is leftover blackbody radiation, then why isn’t its signal swamped by thermal noise within the receiver? Shouldn’t it require a cryogenically chilled receiver, like far-infrared detectors?
As I understand it, cryo-chilled receivers are in fact part of the design for telescopes attempting to measure CMB.
As an example, POLARBEAR says it cools its receivers to 0.3K (http://bolo.berkeley.edu/polarbear/?q=node/7)
If you believe Wikipedia, Penzias and Wilson used a detector cooled with liquid helium when they first detected the CMB.
Ah, I’d been under the impression that it was detectable with ordinary microwave receivers. Ignorance fought.
But only after chasing off some pigeons in the receiver.
That depends on what you mean by “detectable”. The CMB will represent some percentage of the signal in any detector of the appropriate wavelength. It will just be a relatively small percentage, buried under other noise sources, in a non-cryogenic detector.
Like on an old rabbit eared TV.