Sunyaev and
Yakov B. Zeldovich developed the theory for the evolution of density fluctuations in the early universe. They predicted the pattern of acoustic fluctuations that have been clearly seen by WMAP and other CMB experiments in the microwave sky and in the large-scale distribution of galaxies. Sunyaev and Zeldovich stated in their 1970 paper, "A detailed investigation of the spectrum of fluctuations may, in principle, lead to an understanding of the nature of initial density perturbations since a distinct periodic dependence of the spectral density of perturbations on wavelength (mass) is peculiar to adiabatic perturbations." CMB experiments have now seen this distinctive scale in temperature and polarization measurements. Large-scale structure observations have seen this scale in galaxy clustering measurements. With
Yakov B. Zeldovich, at the Moscow Institute of Applied Mathematics, he proposed what is known as the
Sunyaev-Zeldovich effect, which is due to
electrons associated with gas in
galaxy clusters scattering the
cosmic microwave background radiation. Sunyaev and
Nikolay I. Shakura developed a model of
accretion onto
black holes, from a disk, and he has proposed a signature for X-radiation from matter spiraling into a black hole. He has collaborated in important studies of the early universe, including the recombination of hydrogen and the formation of the
cosmic microwave background radiation. He led the team which operated the X-ray observatory attached to the
Kvant-1 module of the
Mir space station and also the
GRANAT orbiting X-ray observatory. Kvant made the first detection of X-rays from a supernova in 1987. His team is currently preparing the
Spectrum-X-Gamma International Astrophysical Project and is working with
INTEGRAL spacecraft data. At Garching he is working in the fields of theoretical high energy
astrophysics and
physical cosmology and participates in the data interpretation of the
ESA Planck spacecraft mission. ==Honors and awards==