Speaker
Description
The Event Horizon Telescope (EHT) has enabled horizon-scale imaging of supermassive black holes. However, constraining black hole spin remains a challenge, despite its importance for testing accretion physics, jet launching, and gravity. Therefore, it is worthwhile to investigate new methods for determining spin, particularly those that make minimal assumptions about the complex astrophysics surrounding the black hole. In this talk, I will present a novel method for constraining spin by utilizing hot spots—localized regions around the black hole that flare up and can appear multiple times in images when the hot spot is bright enough. We demonstrate that the black hole spin (both magnitude and direction) can be recovered from the locations of two lensed hot spot images and their time delay. This is achieved by leveraging the fact that these images originate from the same spacetime event. By numerically tracing back the geodesics of the two images for different spin values, we determine the spin for which the geodesics intersect. Because this method relies solely on the spatial and temporal position of the flare, it is independent of the hot spot’s motion, thereby making virtually no assumptions. Finally, we evaluate the precision of this technique in the context of the EHT at 230 GHz and 345 GHz, as well as space VLBI, to assess its potential for accurate spin measurements.
| Talk category | NOVA Network 3 |
|---|---|
| Preference for a talk or poster | Talk |
| Talk preference for PhD students | Third year |
