Universe PhD Awards for Oliver Pfuhl

In his dissertation, Oliver Pfuhl worked not only on current 8-metre-class telescopes but also on developments for much larger telescopes in the future. This new field of research was the focus of the first part of this thesis „The GRAVITY interferometer and the Milky Way’s nuclear star cluster“. He developed two key-components for one of the most ambitious experiments in modern ground-based astronomy, the GRAVITY interferometer at the ESO Very Large Telescope. The “fiber coupler system” integrates all interferometry subsystems in one compact, effective, and accurately working system, and the “guiding system” provides active compensation of imaging errors along the 100m optical path. GRAVITY will probe the physics of General Relativity by directly resolving the orbital motions of stars close to the event horizon of the central super massive black hole in our Milky Way.

Current telescopes and instruments, however, can already get quite close to our Milky Way black hole. In the second part of the thesis, Oliver Pfuhl used the SINFONI integral field spectrometer at the ESO VLT to investigate the star formation history of the central star cluster. His analysis revealed that more than 80% of the stellar mass close to the black hole must have formed more than five billion years ago. This result agrees with other observations and leads to the spectacular conclusion that the cluster must have formed at times when the mass of the black hole, and therefore its influence on surrounding star formation, was still small.

The selection committee emphasized that “the dissertation by Oliver Pfuhl is an important advancement of astronomical science.”