Pushing the Analogy: Gravitational Lensing by a Schwarzschild Black Hole

Ponente: Dr. Omar López-Cruz (INAOE)
Título:"Pushing the Analogy: Gravitational Lensing by a Schwarzschild Black Hole"
Fecha: Miércoles 02 de agosto (a las 12:00 CDMX / 11:00 ENS)
Lugar: Auditorio Paris Pishmish, zoom Instituto de Astronomía UNAM-CU, CDMX, México

Resumen:
Optical analogies can be used to exploit the properties of gravitational lensing. It is possible to generate axially symmetric lens models to reproduce the effects of lensing by a given mass distribution such as a point mass, a singular isothermal sphere, or a uniform disk (as introduced by Refsdal & Surdej in 1994). Nevertheless, there is no published optical analogy that reproduces the effects of lensing by a Schwarzschild Black Hole (SBH). We have used the new formalism introduced by Gómez-Correa et al. (2022), which is a ray tracing generalization in a symmetric gradient-index media by the application of Fermat's ray invariants. We show that is possible to generate a lens model using a gradient-index (GRIN) media that reproduces the trajectories of photons as they approach the radius of closest approach, rphotosphere = 3GM/c where G is the gravitational constant, M is the black hole mass and c is the velocity of light. Depending on the impact parameter, our model reproduces light deviations by large angle, even returning; orbiting light; and plunging light into the SBH. This insight would help us to measure the mass of ultramassive black holes in cD galaxies using high-resolution sub-mm observations.