European Research Award to Johan Samsing

Gravitational Waves and Black Hole Collisions

Gravitational waves are waves in space and time, and can therefore provide insight into some of the universe's darkest secrets, which have so far been impossible to see through light.

Johan Samsing's work has been centered around how the black holes we see in gravitational waves form and merge in our Universe. Johan Samsing first contributed to this during his PhD at the NBI, where he made the first statistical formulation of the famous 3-body problem with the inclusion of effects from Einstein's General Relativity.

After coupling this to astrophysical models, he later proved that dense systems where such interactions are frequent, produce a well defined fraction of black holes colliding on unique eccentric orbits. 

This measure is now one of the most reliable ways of disentangling classes of binary black hole pathways apart in the new era of observable gravitational wave astrophysics.

Where do the Black Holes Come From?

Gravitational waves have been observed from ~ 100 binary black hole mergers since 2015 that resulted in the Nobel Prize in physics in 2017.

Despite this tremendous breakthrough, it is still unknown how and where binaries form in our Universe; Is it two stars in a binary system that turn into merging black holes? Black holes pairing up through random encounters in dense stellar systems? Super massive black holes that bring binary black holes to merge? Or primordial black holes from the big bang pairing up?

Johan Samsing has been making seminal contributions to this, by e.g. being among the first to identify how dynamically formed mergers show unique distributions across gravitational wave frequency and eccentricity, which can be used to probe their origin.

A future of Gravitational Wave Astrophysics

Many more surprises and possible insight into new physics are expected in the coming decades, where both the space born LISA mission and the ground based Einstein Telescope will see hundreds-of-thousands of black hole mergers across the visible universe. 

For this, Johan Samsing and his group are now preparing with new ideas on how to probe the origin and astrophysical environment of individual black hole mergers through modulations in their gravitational wave signal.

New physics, the nature of dark matter, and other exotica can also be constrained using similar techniques, and J. Samsing and his group have therefore the perfect conditions to make further breakthroughs in the coming decades in this new era of gravitational wave physics.