PhD Project: Gravitational wave (GW) observations with ground-based detectors have revealed a population of stellar-mass black holes (BHs) with higher masses than expected from stellar evolution models. These heavy BHs are thought to form by the repeated merger of smaller BHs. The efficiency of this mechanism is dependent on the environment the BHs are embedded. A possible environment that could facilitate the dynamical assembly of BHs is the accretion disk of an AGN.

With this project, we have developped a statistical (‘dark siren’) framework to infer the fraction of observed GW events coming from BH mergers in AGN accretion disks. This work contributes to our understanding of the formation, evolution and properties of stellar-mass BHs.

PhD Project: When a star passes too close to a supermassive black hole (SMBH), the star gets disrupted by the gravitational tidal forces. Such a tidal disruption events (TDEs) is seen as a bright transient accross the electromagnetic spectrum. TDEs are a promising probe of quiescent SMBHs, but that requires well-modeled light curves. Currently, the origin of the early-time luminosity in optical TDE light curves is unclear. However, the late-time luminosity has been understood to depend on the SMBH mass.

By investigating the correlation between the early-time and late-time luminosity, we can infer a luminosity-mass relation for TDEs. This work allows us to measure quiescent SMBH masses from the best-measured part of the TDE light curve.

Master’s Project: Recently, the system D9 was discovered: a stellar binary in the S-cluster of the Galactic Center, possibly containing a circumbinary disk (Peissker et al., 2024). It is unclear how common D9-like systems are, and therefore how lucky the observation of D9 was. One way to increase the observing probability is for D9 to be stable over sufficiently a long timescale.

In order to test the stability of D9 near the SMBH in the Galactic Center, we perform an N-body+Hydrodynamic simulation of a binary with a disk orbiting an SMBH. We observe Kozai-Lidov (KL) oscillations in both the binary and the disk. The disk loses a fraction of its mass in bursts on the KL timescale. This mechanism does not disrupt D9. We conclude that D9 can survive for a long time in the absence of close gravitational encounters with S-cluster members.