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2014 – Julien Carron and Xavier Dumusque

Two young researchers in Astronomy and Astrophysics awarded by the Prix Schläfli.

Schläfli 2014 Dumusque recherche

Julien Carron was born in 1985 in Sion (Valais). He obtained a Bachelor and a Master in Physics at ETH Zurich, from 2004 to 2009. He performed his master thesis at the Paul-Scherrer institute in Villigen, in the field of non relativistic quantum mechanics, under the supervision of P.D. Roland Rosenfelder. He then joined the group of Prof. Simon Lilly in the institute of Astronomy of ETH for his Phd in cosmology, entitled 'The information content of galaxy surveys' from 2009 to 2012. This included a short term stay in the department of Physics and Astronomy at Johns Hopkins University in Baltimore in the group of Prof. Alex Szalay. Since then he is a Cosmology Postdoctoral Fellow at the institute of Astronomy of the University of Hawaii in Honolulu, in the group of Prof. Istvan Szapudi.

Spatial distribution of galaxies

The largest structures we observe in our Universe form under the action of gravity over enormous distances. The careful observations and subsequent analysis of these structures allow us to test or improve our understanding of fundamental physics, such as alternative theories or gravity and the real nature of dark energy and dark matter. In my research, I contributed to shed light on how to optimally describe these structures and extract the most useful information from their observations. I could show that in cosmology traditional approaches, such as those used in the analysis of the Cosmic Microwave Background, become very inefficient when these structures grow in size (illustrated in the figure), due to the very specific imprint of gravity on their statistical properties. On the other hand, the methods that I used in my research also allow the design of alternative approaches, that summarize better the large scale structures and extract optimally information, allowing us to better constrain physical theories.

Figure: As our Universe evolves from an initial nearly homogeneous state to the present, the statistical properties of its matter content vary dramatically, and with it the adequate manner to describe it and extract most information from it. The curves illustrate how the class of two-point (and higher order) statistics, optimal for Cosmic Microwave Background analysis and at early times, become dramatically inefficient at later times.

Xavier Dumusque is a Swiss astronomer originally from the canton of Vaud. After graduating from the University of Geneva in 2008, he started a PhD in co-tutelle with the University of Porto, Portugal, and the University of Geneva. After obtaining his PhD in 2012 in Geneva, he was award a fellowship from the Swiss National Science Foundation to continue his research abroad, in the well renowned Harvard-Smithsonian Center for Astrophysics in Cambridge, USA. He is now a post-doctoral fellow of the Center for Astrophysics.

Detection of exoplanets

During his PhD, Xavier Dumusque focused himself on detecting the smallest possible planets outside the Solar System. Other worlds can only be detected indirectly by looking to the light of stars hosting planets. However, stars are evolving as a function of time, which perturbs the observations. His main work was to study all the different kind of effect that a star can induce, and find strategies to correct for those. As a result of his work, he was able to detect an Earth-mass planet orbiting the second closest star to the Solar System, named Alpha Centauri Bb. This planet is still now, two years after its discovery, the smallest planet in mass ever discovered. Now, as a post doc in the USA, he continues his research on the same topic, and discovered recently a planet, Kepler-10c, that seems to belong to a new class of extremely massive rocky planets. This new class is challenging all the present planetary formation scenarios.

Le jury du Prix A.F. Schläfli 2014 était présidé par Friedrich-Karl Thielemann du Département de physique de l’Université de Bâle et président de la Platform Mathematics, Astronomy and Physics. Les autres membres du jury étaient: Daniel Pfenniger, Observatoire astronomique, Université de Genève, Willy Benz, Institut de physique, Université de Berne, Georges Meylan, Laboratoire d'astrophysique, EPF Lausanne et Michael Meyer, Institut d'astronomie, ETH Zurich.

Le Prix d’un montant de 5000 francs a été remis en 2014 par la Platform Mathematics, Astronomy and Physics de la SCNAT sur le thème de l’astronomie et de l’astrophysique.

  • Schläfli Carron 2014
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  • Schläfli Dumusque 2014
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