Gravitational Waves
Binary Black Holes
The discovery of gravitational waves (GWs) from binary black holes by the LIGO/Virgo experiments has opened a new window on the Universe. LIGO first detected GWs in 2015, and subsequent detector improvements have greatly increased detection rates, to the point where dozens of merging black holes are seen (or “heard”) per year. However, a crucial zeroth-order question remains unanswered: what astrophysical process is synthesizing these black holes, and in what astrophysical environment does it occur? At least half a dozen different theoretical explanations exist. My group investigates several of these, including one I and others first proposed in 2017: that binary black holes are driven to merger by hydrodynamic forces in the complex environment of active galactic nuclei.
Multimessenger Astronomy
Current and future gravitational wave detections also raise the prospect of multimessenger astronomy: the simultaneous detection of GWs with electromagnetic or other signals. My research group studies the multimessenger signals produced both by high-frequency (LIGO/Virgo-band) GWs synthesized in active galactic nuclei, but also those associated with low-frequency GWs that could be discovered with the future space-based LISA mission. In particular, the merger of a binary supermassive black hole pair sets into motion a chain of events that lead to a burst of tidal disruption flares.