Weak deflection angle of a dirty black hole

Mar 2, 2020
12 pages
Published in:
  • Chin.J.Phys. 66 (2020) 691-702
  • Published: Aug, 2020
e-Print:

Citations per year

20202021202220232024051015
Abstract: (arXiv)
In this paper, we present the weak deflection angle in a Schwarzschild black hole of mass mm surrounded by the dark matter of mass MM and thickness Δrs\Delta r_{s}. The Gauss-Bonnet theorem, formulated for asymptotic spacetimes, is found to be ill-behaved in the third-order of 1/Δrs1/\Delta r_{s} for very large Δrs\Delta r_{s}. Using the finite-distance for the radial locations of the source and the receiver, we derived the expression for the weak deflection angle up to the third-order of 1/Δrs1/\Delta r_{s} using Ishihara (\textit{et al.}) method. The result showed that the required dark matter thickness is 23mM\sim2\sqrt{3mM} for the deviations in the weak deflection angle to occur. Such thickness requirement is better by a factor of 2 as compared to the deviations in the shadow radius (3mM\sim\sqrt{3mM}). It implies that the use of the weak deflection angle in detecting dark matter effects in one's galaxy is better than using any deviations in the shadow radius.
Note:
  • 6 pages, 1 figure; expressions in section 4 simplified thoroughly; accepted for publication in Chinese Journal of Physics
  • Dirty black hole
  • Dark matter
  • Gauss-Bonnet theorem
  • Weak deflection angle
  • Finite-distance
  • black hole: Schwarzschild
  • dark matter
  • deflection
  • angular dependence
  • gravitation