Multiple Honors for Cosmological Visionary

Prof. Rashid A. Sunyaev, a pioneer in high-energy astronomy, has received the Dannie Heineman Prize for Astrophysics and the IAUs Gold Medal for Cosmology

Prof. Rashid A. Sunyaev, Director of Max-Planck-Institut for Astrophysics in Garching has been honored with two prestigious international awards. He received the Dannie Heineman Prize for Astrophysics 2003 from the American Institute of Physics and the American Astronomical Society "for his visionary insights into the interaction of radiation and matter on scales from the Universe to black holes."As well he received the Peter Gruber Foundation and International Astronomical Union's Gold Medal for cosmology ($150,000) for his "pioneering studies on the nature of the cosmic microwave background and its interaction with intervening matter". The Gruber Prize and Gold Medal will be presented to Rashid Sunyaev during the opening ceremony of the 25th General Assembly of the International Astronomical Union on July 15th 2003 in Sydney, Australia.

Rashid A. Sunyaev was born 1943 in Tashkent, Usbekistan in the former USSR. In 1966 he graduated from the Moscow Physical-Technical Institute. From 1965-1968 he was an undergraduate and graduate student of Academician Yakov B. Zeldovich at the Moscow Institute of Applied Mathematics of the USSR Academy of Sciences and received his Ph.D. in astrophysics from the Moscow State University in 1968. From 1974--1982 R.A. Sunyaev was the head of the Theoretical Astrophysics Laboratory at the Space Research Institute (IKI) of the USSR Academy of Sciences. In 1982 R.A. Sunyaev, together with Y.B. Zeldovich created the Department of High Energy Astrophysics at IKI. R.A. Sunyaev was a project scientist for the MIR-KVANT and GRANAT orbital observatories and now leads the Russian participation in the ESA INTEGRAL gamma-ray orbital observatory. Since October 1995 R.A. Sunyaev has been a director at the Max-Planck-Institut for Astrophysik (MPA) in Garching. Prof. Sunyaev has received many top international awards and belongs to several academies.

His main scientific interests are concentrated in physical cosmology, relativistic astrophysics, interaction of matter and radiation and x-ray astronomy. Today his name is associated with a number of fundamental results in astrophysics and cosmology. Among these results are the Shakura-Sunyaev "standard" theory of disk accretion, the Sunyaev-Zeldovich effect and the analytical Sunyaev-Titarchuk formula for spectra formation in hot plasmas due to comptonization (photon-electron scattering).

A seminal paper of Shakura & Sunyaev (1973) "Black Holes in Binary Systems. Observational Appearance" is one of the two most cited works in modern astrophysics. Using the assumption that the radiative efficiency of the disk is high and that turbulent viscosity is a driving mechanism for angular momentum transfer the self-consistent picture of a geometrically thin accretion disk has been developed which is known now as the "standard Shakura--Sunyaev disk". These disks are also known as the "Shakura--Sunyaev alpha disks" since the specific form of the viscosity parameterization suggested by them happened to be particularly simple and fruitful. The clear and elegant physical picture allows one to come up with very detailed predictions of the shape of the emerging spectrum of the accretion disk and presents the possibility of direct comparison with observations. The theory of geometrically thin accretion disks is relevant not only for stellar mass black holes, but also directly applicable to "Active Galactic Nuclei" (AGN) with a simple and clear scaling of all major parameters. The modern theory of accretion continues to evolve with many unanswered questions remaining (in particular in the field of radiatively inefficient flows), but the "standard ShakuraSunyaev disk" remains one of the cornerstones of the theory.

More than 30 years have passed since the publication of the first papers by Yakov Zeldovich and Rashid Sunyaev on the interaction between the "Cosmic Microwave Background" (CMB) radiation and matter in the Universe. Since then this field has evolved from a collection of beautiful theoretical ideas to a set of powerful tools for observational cosmology. The most famous is the so called "thermal Sunyaev-Zeldovich effect" (SZ effect), a small spectral distortion of the CMB spectrum in the direction of clusters of galaxies caused by the scattering of the CMB photons off the distribution of hot electrons in the gravitational potential of the galaxy cluster. High quality detections and images of the SZ effect for more than 50 clusters with redshifts as high as 1 have since become available. New telescopes on the South Pole, at an elevation of 5 km in the Chilean Atacama desert and the planned ESA Planck Surveyor spacecraft open the possibility of discovering tens of thousands of distant clusters undetectable with x-rays or optical light. The Max Planck Society APEX telescope in Chile will be one of the first telescopes opening this new method of investigating the formation of the first massive objects in our universe. These clusters will give us information about key parameters of the universe: dark energy, dark matter, the Hubble constant.

A further phenomena is the "kinetic SZ effect" - an additional spectral distortion due to the Doppler effect of the cluster bulk velocity on the scattered CMB photons, which allows one to measure the peculiar velocity of a distant cluster with respect to the local CMB frame of coordinates. These are now the "textbook" effects and well established methods of observational cosmology.

Astonishing progress in the development of more and more sensitive balloon, space-born and ground based radio and submillimeter telescopes has made possible the recent detection (Boomerang, MAXIMA-1 ballon flights and WMAP spacecraft) of the power density peaks of the CMB fluctuations on the angular scales set by sound waves at the recombination epoch. These peaks were exactly the subject of the Sunyaev and Zeldovich paper (1970) "Small scale fluctuations of relic radiation". The properties of the peaks (in particular their positions and amplitudes) depend sensitively on the cosmological parameters, thus providing a powerful tool for "precision" cosmology. It is truly remarkable that the ideas suggested more than 30 years ago have become the front edge methods of modern observational cosmology today.

Rashid Sunyaev continues to work actively in these fields. He has recently published a series of papers on the polarization of the CMB radiation and detailed analysis of the narrow line broadening induced by Compton scattering on relativistic electrons. A new elegant physical model of the boundary layer between a neutron star and an accretion disk has been recently proposed. This is a problem considering the deceleration of the flow of accreting matter which moves with a velocity close to half of the speed of light due to friction on the surface of the neutron star. The radiation flux generated (and observed) in such boundary layers exceeds the fluxes from the most powerful lasers in earth laboratories.

The Heineman Prize for astrophysics is awarded by the American Institute of Physics together with the American Astrophysical Society. The prize is provided by the Heineman Foundation, founded in 1979, to honor outstanding work done in the area of astrophysics.

The Cosmology Prize of the Peter Gruber Foundation honors those who contribute to fundamental advances in the area of cosmology. Since 2001 the Cosmology Prize has also been supported by the International Astronomical Union.