Shadows of black holes with dark matter halo

Understand

We investigate the shadow of an exact black hole solution of Einstein's equations recently proposed by Cardoso et al., to describe a supermassive black hole immersed in a dark matter halo.

• We analyze and discuss the light rings and the gravitational lensing of this spacetime comparing them with an isolated Schwarzschild black hole.
• Using backward ray-tracing techniques, we study the shadows cast by such black hole when illuminated by a celestial sphere that emits radiation isotropically.
• We find that when the dark matter distribution concentrates near the event horizon of the black hole, multiple light rings emerge.