State Prize of Russia for Rashid Sunyaev

Every year, seven State Prizes are awarded in Russia, of which three are in the area of science and technology, three in literature and the arts and one Prize for humanitarian work. The State Prize ceremony took place on June 12 in the Hall of the Order of St. George in the Grand Kremlin palace and was led by the President of Russia Vladimir Putin.

Rashid Sunyaev and Nikolay Shakura received the Prize for their groundbreaking work on the theory of accretion. The theory of disk accretion onto black holes developed by them in the early 1970s has now become a classical description of the mass transfer and gravitational energy release in stellar binary systems. Based on the assumption that the radiative efficiency of the disc is high and that turbulent and magnetic viscosity is the key driving mechanism for angular momentum transfer, the self-consistent picture of a geometrically thin accretion disk has been developed. Now it is known as a «standard Shakura-Sunyaev disk» or «Shakura-Sunyaev alpha-disk» since the specific form of the viscosity parametrization suggested by Shakura and Sunyaev turned out to be particularly fruitful and efficient.

The clear and elegant physical picture allowed them to formulate detailed predictions about the shape of the emerging spectrum of the accretion disk which permitted direct comparison with observations. They also predicted such phenomena as the formation of gas outflows in super-Eddington accretion regimes and the possibility of their collimation. It was a perfect and timely match of a theoretical prediction and observational capabilities.

The majority of the known black holes have been discovered due to highly luminous disks around them. The theory of geometrically thin accretion disks is relevant not only for stellar mass black holes, but can also be directly applied to supermassive black holes in Active Galactic Nuclei with a simple and clear scaling of all major parameters. It also works in disks around neutron stars and white dwarfs and in protoplanetary disks around young stars.

The modern theory of accretion continues to evolve with many questions still unanswered, but the «standard Shakura-Sunyaev disk» remains to be one of the cornerstones of the theory. With more than 8020 citations, the seminal paper «Black holes in binary systems. Observational appearance» N. Shakura and R. Sunyaev has become the most frequently cited original paper in theoretical astrophysics, among more than three million scientific publications listed in the NASA ADS Astronomy and Astrophysics database.