WMAP Satellite that mapped out the backround microwave radiation. That demonstrated Alan Guth's prediction of that based on inflation theoryï was correct. It has since ben confirmed by more accurate satellite mappings.
Citation please. I don’t believe that
WMAP confirmed inflation. There was a ground-based instrument called “BICEP” that claimed to confirm inflation but was shown to not have when the satellite
Planck data came out. Currently, I believe there is no definitive proof of inflationary theory, but I’m happy to be corrected if you can provide a proper citation.
From Scientific American
.....
When the results from the Planck satellite were announced, they were held up as a confirmation of cosmic inflation," says Avi Loeb, Professor of Astronomy from Harvard University and Vagnozzi's co-author on the new paper. "However, some of us argued that the results might be showing just the opposite."
.....
Their theory involves something called Gravitons. But these have not been detected, and at this point in time cannot be technologically detected. So until such time as that can be accomplished and actually is detected, it is a moot point. The Plank satellite confirms the WMAP findings in greater detail. "Some of us" is not a general consensus. Of course we have theories about Roger Penrose's CCC model, conformal cyclic cosmology, but I find that very dependent on unproven maybes to be able to disprove the Multiverse concept, which derives from observable cosmological phenomena. These theories seem to me about as fragile as Hoyle's steady state cosmology became.
YMMV