Muhammad Haider Khan's Seminar on February 20, 2026

Описание: Speaker: Muhammad Haider Khan, first-year PhD student at the Center for Theoretical Physics, Warsaw, Poland
Title: Lensing, shadow and photon rings in a magnetized black hole spacetime
Date & Time: Friday, February 20, 2026 (02:30 PM)
Venue: Conference Room (9-117), Department of Physics, SBASSE, LUMS

Title: Lensing, shadow and photon rings in a magnetized black hole spacetime.

Abstract: I share results of gravitational lensing, in particular the shadow and photon rings, in the Ernst spacetime, also known as the Schwarzschild-Melvin spacetime, which describes a Schwarzschild black hole immersed in a homogenous magnetic field. Among other things, I give analytic formulas for the vertical diameter of the shadow for an observer at arbitrary inclination and for the horizontal diameter of the shadow for an observer in the equatorial plane. Moreover, I use the strong-deflection formalism for analytically calculating the so-called photon rings of order $\ge 2$ and we use the recently introduced gap parameter $\Delta _2$ for distinguishing lensing of an Ernst black hole from that of a Schwarzschild black hole.
(The abstract has two LaTeX symbols.)

Bio: I am a LUMS Physics graduate on 2022 having completed my Erasmus Mundus Master's in Astrophysics and Space Science in Italy, Serbia and Germany. I am currently a first-year PhD student at the Center for Theoretical Physics, Warsaw, Poland working in gravitational lensing of gravitational waves.