The MERAC prizes were awarded this year (pair) for the best doctoral thesis (Fig. 1). The three prizes corresponded to the following three categories: Theoretical Astrophysics, Observational Astrophysics and New Technologies (Instrumental/Computational/Multi-Messenger). Each prize is accompanied by a grant of 25,000 euros, which can be supplemented by additional MERAC research grants.
Best PhD Thesis in Theoretical Astrophysics
The 2022 MERAC Prize for the best doctoral thesis in theoretical astrophysics was awarded to Helmer Koppelman for his multifaceted approach to the field of galactic archeology, which transformed our understanding of the history and dynamics of the Milky Way. .
Koppelman studied astrophysics at the University of Groningen, where he obtained his doctorate in 2020 on the formation and dynamics of the galactic halo. The outstanding thesis offers insight into the formation of the Milky Way based on the latest available datasets and presents innovative modeling efforts and also provides a new characterization of the properties of the Milky Way’s dark matter halo. Using data from Gaia DR2, he discovered a mass of stars that make up the local galactic halo, which has been interpreted in terms of a large merger event that took place around 10 Gyr ago.
It has pushed the boundaries further by fully exploiting the Gaia DR2 dataset, using all 1.3 billion stars with proper motion information to construct the largest sample of halo stars currently available. Using data mining tools, Koppelman obtained the most accurate lower bound of the Milky Way’s mass. He further investigated the use of orbital frequencies to understand gaps in narrow stellar fluxes, to constrain the presence and properties of dark matter clusters in the galactic halo.
Best PhD Thesis in Observational Astrophysics
The 2022 MERAC prize for the best doctoral thesis in observational astrophysics was awarded to Núria Miret-Roig (University of Vienna, Austria) for the discovery of many new free-floating planets, which shed light on the origin of these exotic nomadic celestial bodies .
Miret-Roig obtained a master’s degree in astrophysics from the University of Barcelona and obtained his doctorate in 2020 from the University of Bordeaux, France. This work presents the discovery of one hundred new floating planets (FFP) in the region encompassed by the Upper Scorpion stellar OB association and the star-forming region of Ophiuchus. This sample is the largest ever discovered and is an important step in defining the class of FFPs and uncovering the origins and characteristics of these mysterious galactic nomads. This allowed him to demonstrate that the gravitational collapse of small clouds alone cannot explain the large fraction of observed FFPs: a significant fraction of them formed as planets but were ejected due to dynamic interactions.
She led an international team to combine images in public astronomical archives with new wide-field deep observations obtained with the world’s best infrared and optical telescopes, to measure the proper motions and photometry of tens of millions of sources in a significant area of the sky. (171 square degrees). Using modern statistical and data mining techniques, Miret-Roig identified the few thousand stars and planets belonging to the young stellar association against the millions of background stars and galaxies. . She presented an innovative methodology to determine the age of young stellar associations based on their kinematics, in particular from Gaia data.
Best Doctoral Thesis in New Technologies (Instrumental)
The MERAC 2022 prize for the best doctoral thesis in new technologies (instrumental) was awarded to Ewelina Obrzud for the development of new laser frequency combs for precise calibration and extreme precision of the radial velocity of astronomical spectrographs.
Obrzud graduated from the Department of Astronomy of the University of Geneva, Switzerland and obtained in 2019 an interdisciplinary doctoral thesis (extrasolar planets and instrumentation) from the same university in collaboration with the Swiss Center for Electronics and Microtechnology (CSEM ), dealing with the construction and demonstration of alternatives to existing laser frequency comb systems for astronomy. It has developed two new laser frequency combs for accurate and precise calibrations of radial velocities. This technique offers interesting solutions and concrete perspectives for the improvement of existing and future high-precision spectrographs for astronomy.
Although driven by astronomical application, Obrzud’s work has also attracted the attention of a wider interdisciplinary community including, in particular, those concerned with optical precision spectroscopy and nonlinear microphotonics.