High spin expansion for null geodesics

Abstract

We consider the high spin expansion for the null geodesics in the Kerr spacetime. We expand the null geodesic equation successively to higher orders in deviation from extremity. Via the method of matched asymptotic expansion, the radial integrals are obtained analytically. It turns out that the analytic expressions are very sensitive to the value of the shifted Carter constant $q$. We show that for a large $q$, the analytic expressions can be used to study observational electromagnetic signatures for astrophysical black holes like M87*. However, for a small $q$, the high spin expansion method can only be applied to (near-) extreme black holes.

25pages, 6 figures, nb source is available, typos fixed, accepted in CQG

References in corpus (12)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole
• First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole
• First M87 Event Horizon Telescope Results. V. Physical Origin of the Asymmetric Ring
• First M87 Event Horizon Telescope Results. II. Array and Instrumentation
• First M87 Event Horizon Telescope Results. III. Data Processing and Calibration
• Influence of a plasma on the observational signature of a high-spin Kerr black hole
• Photon Emission Near Extreme Kerr Black Holes
• Observational signature of a near-extremal Kerr-Sen black hole in the heterotic string theory
• Maximum Observable Blueshift from Circular Equatorial Kerr Orbiters
• Photon Emission Near Myers-Perry Black Holes in the Large Dimension Limit
• Photon emission of extremal Kerr-Newman black holes

Cited by in corpus (5)

• Influence of Quantum Correction on the Black Hole Shadows, Photon Rings and Lensing Rings
• Revisiting the shadow of braneworld black holes
• Observability of Zero-angular-momentum Sources Near Kerr Black Holes
• QED Effects on Kerr Black Hole Shadows immersed in uniform magnetic fields
• Classification of radial Kerr geodesic motion