Topic : Observational Signatures of Black Holes with Multiple Photon Spheres

Speaker: Peng Wang, Sichuan University

Time: 15:00, November 08, 2022

Venue: online

Tencent meeting ID: 360-658-500

Link:  https://meeting.tencent.com/dm/R29iZ2DZXNAR

Abstract: Recently, it has been found that some static black hole solutions can possess two photon spheres of different size outside the event horizon. In this talk, we first consider images of the black holes illuminated by accretion disks and celestial spheres, which may provide unique observational effects for the future detections of black holes with multiple photon spheres. We then discuss quasinormal modes of a scalar field, which are associated with circular null geodesics, and show that there exist long-lived and sub-long-lived modes. Finally, the waveforms of time signals produced by scalar perturbations are constructed in the time and frequency domains. The late-time waveforms can consist of echo signals and a following sinusoid tail, which is controlled by the long-lived or sub-long-lived modes.