2016 Fiscal Year Final Research Report
Analysis of light ray and polarization towards observational verification of black holes
Project/Area Number 
24540282

Research Category 
GrantinAid for Scientific Research (C)

Allocation Type  Multiyear Fund 
Section  一般 
Research Field 
Particle/Nuclear/Cosmic ray/Astro physics

Research Institution  Osaka City University 
Principal Investigator 
ISHIHARA Hideki 大阪市立大学, 大学院理学研究科, 教授 (80183739)

Project Period (FY) 
20120401 – 20170331

Keywords  相対性理論 / 宇宙論 / ブラックホール / 光の測地線 
Outline of Final Research Achievements 
Black hole shadow is expected to be observed if continuous light source is distributed around the black hole. Owing to unstable circular orbits of photon around the black hole, bright ring on the edge of the shadow appears. The radius of the ring is determined by the mass and angular momentum of the black hole. We clarified that the radius of a class of bound orbits of photon around the Kerr black hole approaches to the event horizon if the rotation of the black hole becomes maximum. The shear of the congruence of the photon orbits vanishes, then we can observe the photon orbit winding the horizon of the maximally rotating black holes. Optical vortices, the wave front is helicoid, carry orbital angular momentum. Using an improved eikonal approximation, we derived equations that describe the orbits of optical vortex. Optical vortex around a rotating black hole differs from the null geodesic by the interaction between the optical vortex and angular momentum of the black hole.

Free Research Field 
宇宙論
