Título: Images of Kerr Black Holes with Synchronized Scalar Hair and Their Equatorial Polarization Properties

Lugar: Seminario del DAA. Edificio Investigación Jeronimo Muñoz, planta cuarta, en Burjassot.

Día: miércoles, 11 de marzo de 2026. Hora: 12:00.

Resumen:

In this talk, we present imaging and polarization signatures of geometrically thin accretion disks around rotating Kerr black holes with synchronized scalar hair, described by two massive, time-periodic scalar fields with flat target-space geometry. The presence of scalar hair enriches the geodesic structure of the spacetime, leading to stable light rings and observable deviations from the Kerr prediction.

Using backward ray tracing within the Novikov–Thorne framework, we show that the normalized scalar charge strongly affects the morphology and luminosity of both prograde and counter-rotating disks. The largest deviations appear in the retrograde sector, where new inner emitting rings and enhanced redshifted features emerge.

We also discuss polarization signatures obtained from a synchrotron-emitting equatorial ring model. The scalar fields leave characteristic imprints on the polarization structure, including a reversal in the twist of the electric vector position angle (EVPA) for vertical magnetic fields at high observer inclinations.

These results highlight black hole imaging and polarization as powerful observational probes of synchronized scalar hair in tensor–multi-scalar gravity.