Dr Johan Samsing

Johan Samsing received his PhD in Astrophysics in 2014 from the Niels Bohr Institute, combined with longer stays as a visiting scholar at Berkeley Lab and UC Santa Cruz. After his PhD, he moved to Princeton University as an Einstein Fellow (2014-2017) and Spitzer Fellow (2017-2019). During his time at Princeton, he was also appointed Cotsen Fellow in the Princeton Society of Fellows (2015-2018) and Fellow at Mathey College. In 2019 he returned to the Niels Bohr Institute as a Louis-Hansen Asst. Prof and Marie Curie Fellow. In 2020 he was awarded the Villum Young Investigator group leader grant, and in 2022 the ERC Starting Grant. He is leader of the gravitational-wave (GW) astrophysics group at the Niels Bohr Institute, and works on new ideas on how to probe the origin of binary black hole mergers and other GW sources.

JS formulated during his PhD at the NBI the first statistical description of the famous 3-body problem with the inclusion of effects from Einstein's General Relativity, from which he found a new well defined and unique class of binary black holes merging on eccentric orbits. During his time at Princeton, he coupled his relativistic 3-body solution with astrophysical systems, which allowed him to establish the first consistent framework

for how binary black holes interact and merge in dense environments, from galactic nuclei to stellar clusters. In particular, JS proved how the number of eccentric mergers and their distribution across GW frequency, provide a unique measure of their dynamical origin, which is now one of the most reliable and trustworthy ways of differentiating formation channels apart in the new era of GW astrophysics. At the moment, he works on how to infer the astrophysical environment and formation mechanism of individual compact object mergers using GWs alone, which will play a key-role in the coming decades of GW science in Europe and beyond.