Speaker
Description
The solitonic core is a prediction of ultralight dark matter (ULDM), yet its dynamical response to perturbations from orbiting compact objects remains poorly understood.
The orbit of a black hole embedded within a ULDM soliton is naively expected to decay due to dynamical friction. However, simulations have shown that single black holes can instead undergo “stone skipping”, in which the orbital radius varies quasi-periodically.
In Zhang et al. (arxiv:2602.11512), we show that this behaviour is driven by dipole excitation of the soliton. Using fully nonlinear simulations together with a pipeline for eigenmode decomposition, we identify the dipole mode as the dominant channel mediating the interaction. A complementary forced, damped oscillator description provides a useful interpretation of the resonant energy exchange, demonstrating that the coherent response of the soliton can significantly modify the orbital dynamics.
These results extend linear eigenmode analyses into the nonlinear regime and reveal a dynamical coupling between compact objects and ULDM cores. I will discuss the physical mechanism underlying this resonance, its dependence on mass ratio and damping, and its implications for supermassive black hole dynamics in ULDM halos.
| Research Area | Dark Matter: theory |
|---|