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Spas Stoilov
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let's imagine that we can create a black hole from dark matter. Is it going to be different from the ordinary black hole(which is created by ordinery matter)?
No ( as far as we know).Spas Stoilov said:let's imagine that we can create a black hole from dark matter. Is it going to be different from the ordinary black hole(which is created by ordinery matter)?
"Radiation" is an ambiguous term here. Hawking radiation a priori contains anything that couples to gravity, but unless the temperature is very large (i.e., the BH is very small) in comparison to the mass, emission of massive particles will be severely suppressed.Bandersnatch said:As radiation. Black holes evaporate by radiating.
Mostly as photons and neutrinos up until the BH gets quite small when it gets hot and as Orodruin points out, massive particles can be emitted.Spas Stoilov said:So if we imagine that all matter is returned somehow after black hole evaporation. How it would be returned as a ordinary matter or dark matter?
I think you're making an unwarranted leap there..Scott said:These BHs eat dark matter and eventually emit it as photons and neutrinos (with maybe bigger stuff if the BH fully evaporates).
So, I would guess that there must be a way to convert neutrinos and photons back into dark matter.
Interesting point. Since DM is known to interact gravitationally, it would seem possible that a slow-moving DM particle (assuming DM IS particulate matter) might be captured by a neutron star and that fast moving ones would not.Hmmm... Short of a black hole, can dark matter pass through neutron starts without interacting with them? I wonder if that would be measurable?
Interacting gravitationally is certainly not enough to capture a dark matter particle. You need to additionally get rid of some kinetic energy to become gravitationally bound. This possible process has been very well studied over the last decades, not only in terms of capture on neutron stars, but even more interestingly for capture in the Sun. A dark matter overdensity in the centre of the Sun could possibly lead to DM-DM annihilations into standard model particles. Neutrino telescopes are looking for high-energy neutrinos from the Sun in order to search for this indirect dark matter signature.phinds said:Since DM is known to interact gravitationally, it would seem possible that a slow-moving DM particle (assuming DM IS particulate matter) might be captured by a neutron star and that fast moving ones would not.
Yes, that's exactly why I specified a "slow moving" DM particle; that is, one that would have little kinetic energy.Orodruin said:Interacting gravitationally is certainly not enough to capture a dark matter particle. You need to additionally get rid of some kinetic energy to become gravitationally bound.
This does not matter at all. It still needs to get rid of excess kinetic energy to become gravitationally bound.phinds said:Yes, that's exactly why I specified a "slow moving" DM particle; that is, one that would have little kinetic energy.
OK, I see what you mean but if it were traveling slow enough would it not at least just oscillate back and forth THROUGH the neutron star?Orodruin said:This does not matter at all. It still needs to get rid of excess kinetic energy to become gravitationally bound.
There is just no way for the DM particle to be captured like this without somehow transferring kinetic energy. DM particles from the halo come from very far away, where the potential is basically zero, so essentially regardless of their halo velocity, they will not be gravitationally bound to the star (in other words, they gain enough velocity from falling into the gravitational potential in order not to be bound). They need to get rid of some energy in order to become gravitationally bound. Once this happens through some interaction with the matter in the star, they will have an orbit that at least partially passes through the star and be subject to further interactions. This is the type of processes that eventually would gather the DM particles in the star's core. You can find some of the relevant information along with some more references in one of my latest papers that studied the behaviour of inelastic dark matter in the Sun.phinds said:OK, I see what you mean but if it were traveling slow enough would it not at least just oscillate back and forth THROUGH the neutron star?
Got it. Thanks.Orodruin said:There is just no way for the DM particle to be captured like this without somehow transferring kinetic energy. DM particles from the halo come from very far away, where the potential is basically zero, so essentially regardless of their halo velocity, they will not be gravitationally bound to the star (in other words, they gain enough velocity from falling into the gravitational potential in order not to be bound). They need to get rid of some energy in order to become gravitationally bound. Once this happens through some interaction with the matter in the star, they will have an orbit that at least partially passes through the star and be subject to further interactions. This is the type of processes that eventually would gather the DM particles in the star's core. You can find some of the relevant information along with some more references in one of my latest papers that studied the behaviour of inelastic dark matter in the Sun.
Dark matter black hole is a theoretical type of black hole that is believed to be made up of dark matter, a type of matter that does not interact with light or other forms of electromagnetic radiation. Unlike traditional black holes, which are created from the collapse of massive stars, dark matter black holes are thought to have formed in the early universe from the gravitational collapse of primordial dark matter structures.
The main difference between dark matter black holes and regular black holes is the type of matter they are made of. Traditional black holes are made of regular matter, such as protons and neutrons, while dark matter black holes are made of dark matter particles. Additionally, dark matter black holes are thought to be much smaller and more dense than regular black holes.
Currently, dark matter black holes have not been directly detected. This is because they do not interact with light, making them invisible to telescopes. However, scientists are searching for indirect evidence of their existence, such as through gravitational lensing or by observing their effects on nearby stars and galaxies.
Dark matter black holes are thought to play a significant role in the structure and evolution of the universe. They may have helped shape the distribution of galaxies and other large-scale structures, and their gravitational effects may have influenced the formation of stars and galaxies. Studying dark matter black holes can also provide insights into the nature of dark matter and its role in the universe.
There is currently no evidence to suggest that dark matter black holes pose any danger to humans or the Earth. They are extremely small and are thought to be distributed throughout the universe, so the chances of encountering one are extremely low. Additionally, their lack of interaction with regular matter means that they do not pose a threat to our planet or the objects in our solar system.