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GR: Fachverband Gravitation, Relativistische Astrophysik und Kosmologie
GR 5: Relativistic Astrophysics I
GR 5.3: Vortrag
Dienstag, 17. März 2026, 16:45–17:00, KH 01.016
Photon phenomenology in the accelerated Schwarzschild black hole — •Eva Hackmann1 and Shokoufe Faraji1,2,3,4 — 1Center of Applied Space Technology and Microgravity (ZARM), University of Bremen — 2Department of Physics and Astronomy, University of Waterloo — 3Waterloo Centre for Astrophysics, University of Waterloo — 4Perimeter Institute for Theoretical Physics
We analyse null geodesics in an accelerated Schwarzschild black hole sustained by a cosmic string and/or strut (C-metric) in the sub-extremal regime, and investigate if the acceleration and, in particular, the conicity parameter induced by the string/strut can be constrained from observations. For photons the conformal Hamilton-Jacobi equation separates, and we reduce the radial and polar motion to the Bierman-Weierstrass form, yielding new forms of closed analytic solutions. We show that the conicity parameter has no impact on the location of the fixed photon cone that replaces equatorial symmetry when the acceleration is nonzero, or on the single spherical photon surface shared by all latitudes. On the observational side, we prove that the shadow seen by any observer is an exact circle: its screen radius depends on the acceleration and observer distance but not on observer inclination or the conicity, so the local shadow cannot bound the string tension. We also show how a single shadow measurement with known mass-distance relation uniquely infers the dimensionless acceleration. Finally, we provide compact expressions for the photon circle orbital frequency and Lyapunov exponent and use them to obtain eikonal quasinormal estimates.
Keywords: accelerated black hole; shadow; quasinormal modes; analytical solutions