10
Background
Temp. Fluctuations
•Zeldovich
and Sunyaev in late 1960s:
–Compton scattering by hot electrons in the IGM
leads to a distortion of the background spectrum:
“y”
is Compton scattering optical depth and is the key parameter
here. Note x = (hν/kT).
COBE limits from Page (1997).