It is currently believed that most, if not all, galaxies have supermassive black holes at their centers. These black holes are known as supermassive black holes because they have masses millions or even billions of times greater than our Sun.
The reason we do not see black holes outside of our own galaxy (the Milky Way) is primarily due to the limitations of our current observational capabilities. Detecting and studying black holes in distant galaxies is a challenging task because of the following reasons:
Distance: Galaxies are located at vast distances from us, and the black holes at their centers are relatively small compared to the overall size of the galaxy. This makes it difficult to directly observe individual black holes in other galaxies, as their small size and distance make them appear as mere points of light.
Resolution: Even with advanced telescopes and imaging techniques, our ability to resolve the detailed structures within distant galaxies is limited. This makes it challenging to distinguish the presence of a black hole from other phenomena occurring at the center of the galaxy.
Interference: Interstellar dust and gas can obstruct our view of distant galaxies, making it harder to observe their central regions and identify the presence of a black hole.
Time: Black holes, including supermassive ones, evolve over long timescales. The processes and events associated with black holes can occur on timescales much longer than human lifetimes, making it difficult to observe significant changes directly.
Nonetheless, indirect observational evidence, such as the motion of stars and gas clouds, as well as the energetic phenomena observed in the vicinity of galactic centers, strongly supports the presence of supermassive black holes in many galaxies, including our own Milky Way. Ongoing research and advancements in observational technology will continue to improve our understanding and detection of black holes in galaxies beyond our own.