Routing protocol

Physics

Dark matter

Supermassive black hole

Feature (linguistics)

Computer network

Black hole (networking)

Biology

Link-state routing protocol

Galaxy

Astronomy

Stars

Horizon

Philosophy

Horticulture

Theoretical physics

Computer science

Linguistics

Astrophysics

Routing (electronic design automation)

Black spot

Physical review. D/Physical review. D.

Pushed by a number of advances, electromagnetic observatories have now reached the horizon scale of supermassive black holes. The existence and properties of horizons in our universe is one of the outstanding fundamental issues that can now be addressed. Here we investigate the ability to discriminate between black holes and compact, horizonless objects, focusing on the lensing of hot spots around compact objects. We work in particular with boson and Proca stars as central objects, and show that the absence of a horizon gives rise to a characteristic feature---photons that plow through the central object and produce an extra image. This feature should be universal for central objects made of matter weakly coupled to the standard model.

Observational signatures of hot spots orbiting horizonless objects