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The residual light radiation revealed a huge black hole..
It is not difficult to understand that a massive and very large black hole without an infusion from outside will not be as big as it is being surrounded by dust,gas and a huge array of stars. Apparently, for this reason, the scientific community mainly detects super large black holes in the central regions of galaxies and large star clusters. Having a huge gravitational force, a black hole forms a stable field seeded with stellar mass around itself, sometimes one or a couple of stars critically approach the black hole and then the source of stellar matter towards the black hole occurs, the hole at this time receives a bright glowing halo of heated plasma in its orbit. Absorbing plasma in such a simple way, the black hole gets an increase in weight every time. When a black hole is located in the center of a galaxy and has many satellites in the form of stars at a small distance, such galaxies are called "Galaxies with an active core"
AGN is an active galactic core, at some stage it still dims and eventually goes out. The thing is that a supermassive black hole can be fed indefinitely, but at some stage it remains stably lonely, and the nearest star for absorption is so far away that even with a huge gravitational force, it can no longer be reached.
Recently, Japanese scientists have found the central region of one of the galaxies just at the stage of its extinction. Something similar was revealed by observing the galaxy Arp 187.
The central region of this galaxy was monitored by two ALMA and VLA telescopes at once, and lo and behold, a huge jet jet burst out of the central region of this galaxy, it later turned out that the absorption of the core by the black hole had long been completed, and scientists received only a belated signal about it, which in some way indicated that a very large and lonely black hole was hiding in the central part of the core of this galaxy.
Studying the radiation in more detail, Japanese scientists came to the conclusion that if we count the time more accurately, the core stopped actively glowing in the galaxy 3000 years ago. And what scientists have seen now is just a light representation from the distant past.
To learn as much as possible about this galaxy, scientists used the NuSTAR orbital X-ray telescope, and it was this satellite and its instruments that confirmed that the core of the galaxy Arp 187 is no longer active. The core has gradually degraded by radiation and at this time it is already glowing at least 1000 times weaker than the initial, active period. Then everything will only fall in the light equivalent...
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