The main challenge astronomers face when trying to directly detect black holes is that black holes do not emit light or any electromagnetic radiation that can be detected with traditional telescopes. Since they have such strong gravitational pull that not even light can escape from them, they are inherently invisible.
To infer the presence of black holes, astronomers often rely on indirect methods, such as observing the effects of a black hole's gravity on nearby objects and light. For example, they can detect the motion of stars orbiting around an invisible mass or observe high-energy emissions from material being drawn into a black hole (accretion disks). The challenge lies in distinguishing these indirect signs of black holes from other astronomical phenomena and ensuring accurate characterization of the black hole's properties despite the lack of direct visual evidence.
1 answer