16–20 Jun 2025
Varna, Bulgaria
Europe/Sofia timezone

Rotating Black Holes with Scalar Hair: Imaging in Non-Flat Target Spaces

20 Jun 2025, 16:20
15m
Varna, Bulgaria

Varna, Bulgaria

Hotel Cherno More, Greek NeighborhoodOdesos, bul. "Slivnitsa" 33, 9000 Varna
Oral presentation

Speaker

Dr Galin Gyulchev (Sofia University "St. Kliment Ohridski")

Description

We investigate the visual appearance of thin accretion disks and their embedded shadows around rotating black holes endowed with scalar hair, generated by two time-periodic scalar fields whose target space possesses non-flat geometry. These solutions extend beyond the Kerr framework and exhibit a non-trivial geodesic structure that significantly influences observable features. By varying the normalized scalar charge and the Gaussian curvature of the target space, we identify distinct transitions in both disk and shadow morphology. As the system approaches the boson star limit, the shadows fragment into highly chaotic, disconnected regions. At intermediate values of the scalar charge, a well-defined central shadow emerges, with its shape closely linked to the curvature. The accretion disk images reflect this trend: low curvature yields distorted, non-simply connected patterns, whereas higher curvature produces more coherent and symmetric configurations. For low scalar charge, the visual signatures converge toward those characteristic of a Kerr black hole.

Authors

Dr Galin Gyulchev (Sofia University "St. Kliment Ohridski") Dr Daniela Doneva (University of Tuebingen) Prof. Stoytcho Yazadjiev (University of Tuebingen) Petya Nedkova (Sofia University "St. Kliment Ohridski")

Presentation materials