Laureates of the Victor Ambartsumian International Science Prize 2020

Prof. Alexander Szalay
(Johns Hopkins University, USA)

Prof. Isabelle Baraffe
(University of Exeter, UK)

Prof. Adam Burrows
(Department of Astrophysical Sciences, Princeton University, USA)
The prize is awarded for:

"his pioneering work on demonstrating that the Dark Matter in the Universe might be a neutral, weakly interacting particle and for his contributions to data-driven, statistical cosmology"

"her fundamental contributions to the field of low mass stars, brown dwarfs and exoplanets, and for innovative ideas in the domains of asteroseismology and compact binaries"

"his seminal and pioneering contributions to the theories of brown dwarfs and exoplanets and for his leadership role in educating a generation of scientists at the frontiers of brown dwarf and exoplanet research"

Statement concerning the work of the laureates:

Prof. Alexander Szalay

Prof. Szalay’s research has been carried out in a number of areas:

Massive Neutrinos

Szalay was a pioneer in the field of astro-particle physics. He was the first to recognize the importance of neutrino mass on the fluctuations in the Universe (Marx and Szalay, 1972, Szalay and Marx, 1976). These were the first papers to consider a characteristic scale emerging from relic particles. Bond and Szalay (1983) were the first to introduce the concept of hot, cold and warm dark matter.

Galaxy Formation with Dark Matter

Today, dark matter is a central tenet of modern cosmology, and the search for dark matter is an important part of particle physics. The basic paradigm in galaxy formation today is the biased cold dark matter scenario, which was first discussed in detail in Bardeen, Bond, Kaiser and Szalay (1986). This paper the paper that laid the foundations for the modern theory of galaxy formation, and it is still one of the most cited papers in cosmology.

Photometric Redshifts

With collaborators Koo and Connolly, Szalay pioneered an improved way to estimate distances to galaxies based upon their broadband color. This method has substantially changed the way ongoing surveys are carried out (SDSS, DEEP), and has been also extensively applied to the Hubble Deep Field (Connolly et al, 1996, Connolly et al, 1997). Today, this technique is used extensively, from observations at the Hubble Space Telescope to ground-based studies of distant supernovae or gravitational lenses. Hundreds of millions of galaxies have been analyzed using this technique.

Novel Statistical Techniques

Szalay derived several new statistical estimators for astronomy and Large-Scale Structure, which are substantial improvements over their predecessors, and became the method of choice in modern cosmology. Some of these represent a new result in applied probability theory (Landy and Szalay, 1993).

Baryon Acoustic Oscillations

Broadhurst, Ellis, Koo and Szalay (1990) have found arguably the first traces of the Baryon Acoustic Oscillations (BAO). Szalay (1998) has pointed out correctly, that for their detection to be the result of BAO the Universe had to have a higher baryon content, and a lower Hubble constant, than the models at the time predicted.

Redshift Space Distortions

With Matsubara he has developed the theory of redshift-space distortions over wide angles, enabling the use of this technique with large-area sky surveys, like SDSS (Szalay, Matsubara, Landy 1998). He pointed out the amplification of BAO due to this effect and used it to detect BAO in the SDSS normal galaxies.

Sloan Digital Sky Survey

Szalay is a key member of the Sloan Digital Sky Survey, a computer-driven large-scale survey of the sky. He is the architect for the Science Archive of the Sloan Digital Sky Survey. He collaborated with Jim Gray of Microsoft to design an efficient system to perform data mining on the Archive of the Sloan Digital Sky Survey (SDSS), based on innovative spatial indexing techniques. The SDSS Science Archive has attracted an unprecedented number of users, and is considered to be an example for on-line archives of the future. Szalay undertook a part of the SDSS that nobody else wanted to do, and turned this service job into what is perhaps the most important legacy outcome of SDSS, and what became one of the world’s most used astronomy resources.

Virtual Observatory

Szalay’s work on the Virtual Observatory exemplifies his visionary approach to science. He thought to leverage the power of the internet to create a Virtual Observatory – not limited by time or space. He started a grass-roots effort that is leading to a National Virtual Observatory in the United States. The idea is rapidly spreading worldwide, with allied efforts underway in more than twenty countries. The Virtual Observatory effort serves as a showcase for other sciences in how to make data open and accessible.

The Fourth Paradigm of Science

With Jim Gray, Tony Hey and Gordon Bell he has been one of the early advocates of the Fourth Paradigm: how data is driving new discoveries in science. He has been actively engaged with domain scientists in many different disciplines, from astrophysics to medicine and turbulence research.

Prof. Isabelle Baraffe

Isabelle Baraffe has produced important work in the fields of stellar and planetary astrophysics, encompassing a wide range of physical domains, from Earth-like planets to very massive stars and compact binaries. Her work aims at understanding and properly describing the physical processes characteristic of the formation, structure and evolution of substellar (planets, brown dwarfs) and stellar objects.

With her collaborators Gilles Chabrier and France Allard, Isabelle Baraffe made fundamental contributions to the domain of brown dwarfs and low-mass stars (the dominant stellar population in galaxies). Brown dwarfs are not massive enough to sustain or even ignite hydrogen fusion in their core and provide the missing link between stars and planets. They were discovered only in 1995. Isabelle Baraffe developed along the years a coherent theory for describing the internal and atmospheric structures of low-mass stars and brown dwarfs based on state-of-the-art description of all the micro-physics characteristic of these objects. The Baraffe et al. models explain and even predict all the peculiar observational properties of the aforementioned astrophysical bodies. These models revolutionised the field and established a new paradigm that has sustained for more than 20 years. Her models are widely used by the community to interpret observations and to develop new observational strategies.

Recently, Baraffe demonstrated that early phases of accretion during the birth of the object have a crucial impact on the evolution of young low mass stars and brown dwarfs, even long after accretion has ended. This idea completely changed the standard picture of the early evolution of nascent stars and brown dwarfs, and explained various puzzling properties of young objects, leading to a revision of the standard concept of early phases of evolution.

With Chabrier and Travis Barman, Baraffe developed a general theory that described the inner structure, atmospheric properties and evolution of planets over the entire mass range from Earth-mass to Jupiter-mass bodies. Their models include not only the essential planetary input physics, but also peculiar processes, such as atmospheric evaporation due to the intense parent star incident flux for the short-period transiting planets, double-diffusive layered convection and energy dissipation in the interior due to tidal effects. These models are used widely by the community and provide a theoretical foundation for the analysis of observational data obtained with the largest telescopes worldwide.

While in Exeter, she initiated a major interdisciplinary project in the field of exoplanet atmospheric dynamics. She led the development of the most advanced, three-dimensional radiative hydrodynamics models of exoplanet atmospheres, which are necessary to analyse the wealth of data expected from new generations of telescopes, and to obtain key information such as planet atmospheric chemical composition, the necessary path to better understand planet formation and to detect biosignatures on Earth-like planets.

Isabelle Baraffe was awarded an advanced European Research Council (ERC) grant in 2013, which allowed the development of a highly novel numerical tool, specifically the fully compressible, time implicit, three-dimensional (3D) code MUSIC (MUlti-dimensional Stellar Implicit Code). The significant potential for this new tool was recognized by the award of a second advanced ERC grant in 2018.

Isabelle Baraffe’s personal ambition is to advance the very frontiers of astronomy, taking stellar and planetary physics to a new era and to make it one of the major domains of 21st century astronomy. To achieve this, Professor Baraffe has led highly innovative projects such as the development of complex numerical tools that combine state-of-the-art physics and computational methods.

Prof. Adam Burrows

Dr. Burrows is an internationally-recognized pioneer in the fields of brown dwarfs and exoplanets, in particular their atmospheres, spectra, chemistry, and evolution. His models have informed a generation of astronomers engaged in their study and he has played a pivotal leadership role in the explosive growth and maturation of the study of these intriguing objects.

Adam Burrows was one of the first, if not the first, theorist in the world to work on what are now called exoplanets. Just in advance of the first detection of a giant exoplanet (51 Peg b) around a sun-like star, he inaugurated the theoretical exploration of giant exoplanet evolution ("Prospects for Detection of Extra-Solar Giant Planets by Next-Generation Telescopes", A. Burrows et al., Nature, 375, 299 1995). He established the first theory group in the world working on, and at the intersection of, brown dwarfs and exoplanets. Many of the junior researchers in his group (e.g., T. Guillot, J. Fortney, M. Marley, and D. Saumon) went on to assume substantial leadership roles in brown dwarf and exoplanet science. Moreover, his group was responsible for forging and promoting the early atmospheric, spectroscopic, and evolutionary links between brown-dwarf and giant exoplanet studies. These connections were further developed and articulated in a series of influential reviews ("The Science of Brown Dwarfs", A. Burrows & J. Liebert, Rev. Mod. Phys., 65, 301, 1993; "Chemical Equilibrium Abundances in Brown Dwarf and Extrasolar Giant Planet Atmospheres", A. Burrows & C. Sharp, Ap.J., 512, 843, 1999; "The Theory of Brown Dwarfs and Extrasolar Giant Planets", A. Burrows et al., Rev. Mod. Phys., 73, 719, 2001; and "Atomic and Molecular Opacities for Brown Dwarf and Giant Planet Atmospheres," C. Sharp & A. Burrows, Ap.J. Suppl., 168, 140, 2007) that educated a generation of exoplanet astronomers in the astrophysics of brown dwarfs and giant planets. In the process, he created benchmark evolutionary and spectral models used world-wide (e.g., "A Non-Gray Theory of Extrasolar Giant Planets and Brown Dwarfs", A. Burrows et al., Ap.J., 491, 856 1997). As a secondary consequence, these models are the source for the internationally-used and IAU-sanctioned demarcation mass (13 Jupiter masses) between brown dwarfs and giant planets based on their calculated deuterium burning limit. In addition, Dr. Burrows explained most of the optical spectra of brown dwarfs in terms solely of alkali metal lines and their broad wings ("The Near-Infrared and Optical Spectra of Methane Dwarfs and Brown Dwarfs", A. Burrows, M. Marley, & C. Sharp, Ap.J., 531, 438, 2000) and introduced the importance, since verified, of such strong alkali doublets in the context of giant exoplanet atmospheres and spectroscopy. Furthermore, Dr. Burrows led in the early development of modern models of exoplanet emission and reflection spectra, albedos, and light curves (e.g., "Albedo and Reflection Spectra of Extrasolar Giant Planets", D. Sudarsky, A. Burrows, and P. Pinto, Ap.J., 538, 885, 2000; ``Spectra and Diagnostics for the Direct Detection of Wide-Separation Extrasolar Giant Planets," A. Burrows, D. Sudarsky, and I. Hubeny, Ap.J., 609, 407, 2004; "Spectral and Photometric Diagnostics of Giant Planet Formation Scenarios", D. Spiegel & A. Burrows, Ap.J., 745, 174, 2012) and anticipated the discovery of what are now termed "Y dwarfs" (the coolest brown dwarfs) in "Beyond the T Dwarfs: Theoretical Spectra, Colors, and Detectability of the Coolest Brown Dwarfs" (A. Burrows, D. Sudarsky, and J. I. Lunine, Ap.J., 596, 587, 2003).