Kippenhahn Award for Aniket Agrawal and Jens Stücker

July 19, 2018
The 2018 MPA summer party was not only a special thank you to this year’s Biermann lecturer Alice Shapley, UCLA, but also the occasion to congratulate two junior MPA scientists to their Kippenhahn Awards. Aniket Agrawal was honoured for his paper on “Large tensor non-Gaussianity from axion-gauge field dynamics”. Jens Stücker received the award for his paper “The median density of the Universe”.

The Kippenhahn Award is bestowed jointly by MPA and its former director Rudolf Kippenhahn to the best student paper of the year, judged by a committee of several MPA scientists. This year, the committee had a hard task ahead of them: all ten proposals were strong contributions to the scientific fields covered by the institute. In the end, the committee decided to recognise two students.

It has been widely assumed that the detection of primordial gravitational waves from inflation in, for example, the B-mode polarisation of the cosmic microwave background immediately implies the discovery of the quantum nature of space-time. While this statement is true for the vacuum solution, it does not apply if the gravitational waves originate from matter fields. How can we distinguish between these two origins? The answer is non-Gaussianity.

For the first time Aniket Agrawal shows in his paper “Large tensor non-Gaussianity from axion-gauge field dynamics” that gravitational waves from SU(2) gauge fields during inflation are highly non-Gaussian, whereas those from the vacuum are only weakly non-Gaussian. This paper significantly influences the way experimentalists test the physics of inflation using gravitational waves.

Recent studies of fluctuations in the cosmic microwave background radiation have measured the average matter density of today’s universe to an accuracy approaching one percent. Surprisingly, however, the matter density at a typical point is unknown, even to the order of magnitude.

In his paper “The median density of the Universe”, Jens Stücker uses a modified excursion set approach to calculate for the first time the unsmoothed present-day matter density distribution at random points in space for the standard LCDM cosmology. He found that the median density is much lower than the mean and depends significantly on the nature of dark matter.

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