Astronomers have suggested that Planet Nine could be a black hole that can be detected with the Vera Rubin Observatory's telescope. According to the calculations of the researchers, published on arXiv.org, if a small celestial body passes by the black hole, the instrument will be able to see the explosion that occurred during its destruction.
In 2016, Caltech scientists Konstantin Batygin and Michael Brown published an article in which they presented circumstantial evidence for the existence of the famous Ninth Planet. According to their hypothesis, its possible mass is 5-10 Earths, and when moving in orbit, it is located from the Sun in 300-1000 astronomical units (one astronomical unit is equal to the average distance from the Earth to the Sun). At the same time, it has not yet been possible to directly see the celestial body - its presence is indicated only by anomalies in the orbital parameters of known objects in the Kuiper belt.
On the other hand, the researchers assume that with about the same degree of probability, the unusual behavior of asteroids and dwarf planets beyond the orbit of Neptune can explain the presence of a black hole. Amir Siraj and Abraham Loeb of Harvard University suggested that the black hole could be found by an optical signal. If one of the bodies of the Oort cloud comes too close to the black hole, it will be destroyed by its gravity, and when the matter heats up, a flash will occur. However, this signal will be quite weak and not every telescope will be able to see it.
Therefore, the researchers decided to check whether such a flash will be able to "catch" the wide-angle observation telescope-reflector at the Vera Rubin Observatory, which is being built in Chile today. It is planned that the instrument will see the first light next year and will study weak microlensing in deep space, as well as small bodies of the solar system.
Astronomers have carried out calculations that showed that the telescope will be able to register at least several such flares a year. In this case, scientists will be able to confirm that the Ninth planet is a black hole, and in the future find out its orbital parameters. In addition, if Planet Nine is a black hole surrounded by a magnetic field (the black hole does not have its own magnetic field, but it can arise from the accretion disk), then the synchrotron radiation from the matter around it can make the flares much brighter, which means they will be easier to detect. …
Astronomers have long speculated that the solar system may be surrounded by small black holes - this could explain the excess of microlensing events. In addition, there are suggestions that black holes formed in the early Universe may be "particles" of dark matter.