Talks

The existence of fermionic compact objects, such as neutron stars, is supported by a plethora of observational evidence — an intriguing idea is whether one can construct stars made up of the bosonic counterparts. Such theoretical objects are called boson stars, proposed to make up a fraction of the dark matter in our Universe and claimed to be promising horizonless black hole mimickers. In this talk I will discuss the state-of-the-art of numerical evolutions of boson star models in spherical symmetry. In particular, I will discuss how improper initial data construction can lead to spurious physical effects in the evolution of boson star mergers and introduce methods, necessary to remedy such spurious features. I will present our results on boson star head-on collisions of various mass ratios, highlighting the differences from the black hole mergers. Lastly, I will discuss our recent results on the high-precision numerical relativity simulations of quasi-circular boson star inspirals in pursuit of understanding the implications of boson star signatures on the LIGO-Virgo-KAGRA observations.

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In this talk I will show how the gravitational potentials generated by ultralight dark matter halos interact with gravitational waves, resonantly amplifying them. Significant amplifications can be achieved in dense dark matter environments, where the Floquet exponent is increased. The frequency of the amplified gravitational wave is equal to the axion mass when one requires resonance in the first band. For some masses considered, the gravitational wave frequencies fall within the Pulsar Timing Array range, representing an interesting possibility to test ultralight axions as dark matter candidates.

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Zoom link