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One topic that interests me is supermassive black holes. Do you think they can exist? Also, have any been reported?
I tought that was impossible. I thought that if two black holes came within proximity of each other's acression disks, they would be destroyed or just reppled from each other. Does anyone know what would happen if two black holes got too close together? Is black hole merging even possible?Matterwave said:One speculative origin of SMBHs is that they formed from the merger of many smaller black holes over a long period of time.
Jonathan Scott said:Supermassive objects have been shown to exist in the cores of galaxies. However, as far as I know, there is currently no experimental evidence which allows us to determine for certain whether those objects are actually the weird "black hole" objects, involving event horizons and singularities, which arise from pushing GR theory to its limits.
These objects as currently observed are of course far from black, in that they emit huge amounts of electromagnetic radiation and are some of the most luminous objects in the universe, but black hole theory explains that this emission is coming from accretion disks around the hole rather than the object itself, and the nature of a large part of these emissions is consistent with this hypothesis. However, accretion disks could also be present if the central object was not in fact a black hole.
There is also some evidence suggesting that such objects have strong intrinsic magnetic fields, which is not consistent with the currently predicted properties of a black hole.
Nabeshin said:I was under the impression we were quite certain they were indeed black holes, for no amount of matter could be compressed in such a small volume to form anything but a black hole.
Matterwave said:The periapsis of the stars around the SMBH gives us an upper limit to the radius of the object. I think, but I'm not 100% sure, that this radius is within the Schwarzschild radius.
Is there actually a competing theory that describes the emissions without the central object being a black hole? Or is this just a quibble about the definition of "black hole"? We've had that discussion before...Jonathan Scott said:These objects as currently observed are of course far from black, in that they emit huge amounts of electromagnetic radiation and are some of the most luminous objects in the universe, but black hole theory explains that this emission is coming from accretion disks around the hole rather than the object itself, and the nature of a large part of these emissions is consistent with this hypothesis. However, accretion disks could also be present if the central object was not in fact a black hole. [emphasis added]
russ_watters said:Is there actually a competing theory that describes the emissions without the central object being a black hole? Or is this just a quibble about the definition of "black hole"? We've had that discussion before...
A supermassive black hole is a region in space with an extremely high gravitational pull that is caused by a concentration of mass. They are much larger and more massive than regular black holes, with masses equivalent to billions of suns.
Supermassive black holes are believed to form through the accumulation of matter over time. This matter can come from the collapse of a large gas cloud, the merging of smaller black holes, or the accretion of matter from surrounding stars and galaxies.
Supermassive black holes are typically found at the center of galaxies, including our own Milky Way. They are also commonly found in active galactic nuclei, which are extremely bright regions in the center of galaxies that are powered by the accretion of matter onto the black hole.
While we cannot directly see a supermassive black hole, we can observe its effects on the surrounding matter. This includes the gravitational influence on stars and gas, as well as the radiation emitted by the accretion disk. Scientists use a variety of telescopes and instruments to study these effects and learn more about supermassive black holes.
No, supermassive black holes are not a threat to Earth. The closest known supermassive black hole is located in the center of our galaxy, about 25,000 light-years away, and poses no danger to us. However, their immense gravitational pull can play a crucial role in shaping the evolution and structure of galaxies.