Temperature fluctuations of cosmic microwave background induced by gravitational lensing

Adopting the accepted interpretation of the cosmic microwave background (CMBR) as a relic of the early hot universe we show that any angular intensity variations existing in the background at the “last scattering surface” at the redshift of ∼10³ will induce bright fluctuations through gravitational lensing by intervening masses. The resulting temperature variations ΔT are estimated for gravitating masses like distant galaxies (z ∼ 1) and local dark objects (e.g. population III stars) in our own Galaxy. It is found that the value of ΔT/T produced by the above mechanisms further constrains the theories of galaxy formation. The calculation also limits the amount of matter present in the form of population III objects in the galaxy.