An inhomogeneous pseudo-scalar field configuration behaves like an optically active medium. Consequently, if a light ray passes through an axion cloud surrounding a Kerr black hole, it may experience a polarization-dependent bending. We explore the size and relevance of such effect considering both the QCD axion and a generic axion-like particle.
A. Plascencia and A. Urbano
Thu, 23 Nov 17
Comments: Bulk of 29 pages + 11 figures