Head on collision of two black holesIf two black hole event horizons overlap (touch) can they ever separate again?Collision of 2 black holesWhat happens when two black holes collide?highspeed black holes or neutron stars on (almost) head-on collision course and kinetic energyHow close would merging black holes have to be to feel gravitational waves?Why black holes have positive energy?Why do “they” portray colliding black holes like that?Can a black hole undergo a Penrose process inside another black hole's ergosphere?Why do neutron stars collide instead of just revolving around each other like planets revolve around the Sun?Would LIGO Detect Head-On Collision?If two black hole event horizons overlap (touch) can they ever separate again?
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Head on collision of two black holes
If two black hole event horizons overlap (touch) can they ever separate again?Collision of 2 black holesWhat happens when two black holes collide?highspeed black holes or neutron stars on (almost) head-on collision course and kinetic energyHow close would merging black holes have to be to feel gravitational waves?Why black holes have positive energy?Why do “they” portray colliding black holes like that?Can a black hole undergo a Penrose process inside another black hole's ergosphere?Why do neutron stars collide instead of just revolving around each other like planets revolve around the Sun?Would LIGO Detect Head-On Collision?If two black hole event horizons overlap (touch) can they ever separate again?
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
$begingroup$
Inspired by If two black hole event horizons overlap (touch) can they ever separate again?, I was wondering what would happen if two black holes collided into each other in a head-on collision.
In this model there's two black holes on a 3d Cartesian plane. Each black hole has a mass of 1 billion solar masses, and they're both going 0.9c. They're traveling on the z axis in opposite directions.
If both black holes are not spinning, one traveling positive z, the other in negative z, and collide at the origin in a perfect head-on collision what would be the result?
How long would a full merger take, and what would the resulting spin be? Would there be a large wave of gravitational energy, or some other emission?
black-hole supermassive-black-hole collision
asked 8 hours ago
KGlasierKGlasier
1063 bronze badges
New contributor
KGlasier is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
Inspired by If two black hole event horizons overlap (touch) can they ever separate again?, I was wondering what would happen if two black holes collided into each other in a head-on collision.
In this model there's two black holes on a 3d Cartesian plane. Each black hole has a mass of 1 billion solar masses, and they're both going 0.9c. They're traveling on the z axis in opposite directions.
If both black holes are not spinning, one traveling positive z, the other in negative z, and collide at the origin in a perfect head-on collision what would be the result?
How long would a full merger take, and what would the resulting spin be? Would there be a large wave of gravitational energy, or some other emission?
black-hole supermassive-black-hole collision
asked 8 hours ago
KGlasierKGlasier
1063 bronze badges
New contributor
KGlasier is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
$begingroup$
There won't be spin - impulse moment conserves also in the GR. There would be gravitational wave emission, although much smaller and a very different characteristic than the currently observed ones. The time of the full merge will be calculable by a GR free-fall.
$endgroup$
– peterh
8 hours ago
$begingroup$
Why would it be much smaller @peterh? If the two BH were moving in polar opposite directions in a head-on collision, wouldn't there be a large wave since all that momentum just... stops? There'd have to be a release of energy somewhere.
$endgroup$
– KGlasier
8 hours ago
1
$begingroup$
No. The black holes are modelled as point-like masses, with an event horizon around them. The gravitational waves are coming from the event horizons, more exactly from the space around the event horizons. No one knows, what will happen if the point-like masses collapse, because the current science stops far before that. What is known, are the known conservation laws of the GR. These don't predict very big things. However, I am just an educated layman. Hopefully a professional will come up with more convincing arguments as well.
$endgroup$
– peterh
8 hours ago
add a comment |
$begingroup$
Inspired by If two black hole event horizons overlap (touch) can they ever separate again?, I was wondering what would happen if two black holes collided into each other in a head-on collision.
In this model there's two black holes on a 3d Cartesian plane. Each black hole has a mass of 1 billion solar masses, and they're both going 0.9c. They're traveling on the z axis in opposite directions.
If both black holes are not spinning, one traveling positive z, the other in negative z, and collide at the origin in a perfect head-on collision what would be the result?
How long would a full merger take, and what would the resulting spin be? Would there be a large wave of gravitational energy, or some other emission?
black-hole supermassive-black-hole collision
asked 8 hours ago
KGlasierKGlasier
1063 bronze badges
New contributor
KGlasier is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
Inspired by If two black hole event horizons overlap (touch) can they ever separate again?, I was wondering what would happen if two black holes collided into each other in a head-on collision.
In this model there's two black holes on a 3d Cartesian plane. Each black hole has a mass of 1 billion solar masses, and they're both going 0.9c. They're traveling on the z axis in opposite directions.
If both black holes are not spinning, one traveling positive z, the other in negative z, and collide at the origin in a perfect head-on collision what would be the result?
How long would a full merger take, and what would the resulting spin be? Would there be a large wave of gravitational energy, or some other emission?
black-hole supermassive-black-hole collision
black-hole supermassive-black-hole collision
asked 8 hours ago
KGlasierKGlasier
1063 bronze badges
New contributor
KGlasier is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 8 hours ago
KGlasierKGlasier
1063 bronze badges
New contributor
KGlasier is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 8 hours ago
KGlasierKGlasier
1063 bronze badges
New contributor
KGlasier is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 8 hours ago
KGlasierKGlasier
1063 bronze badges
asked 8 hours ago
KGlasierKGlasier
1063 bronze badges
1063 bronze badges
New contributor
KGlasier is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
KGlasier is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$begingroup$
There won't be spin - impulse moment conserves also in the GR. There would be gravitational wave emission, although much smaller and a very different characteristic than the currently observed ones. The time of the full merge will be calculable by a GR free-fall.
$endgroup$
– peterh
8 hours ago
$begingroup$
Why would it be much smaller @peterh? If the two BH were moving in polar opposite directions in a head-on collision, wouldn't there be a large wave since all that momentum just... stops? There'd have to be a release of energy somewhere.
$endgroup$
– KGlasier
8 hours ago
1
$begingroup$
No. The black holes are modelled as point-like masses, with an event horizon around them. The gravitational waves are coming from the event horizons, more exactly from the space around the event horizons. No one knows, what will happen if the point-like masses collapse, because the current science stops far before that. What is known, are the known conservation laws of the GR. These don't predict very big things. However, I am just an educated layman. Hopefully a professional will come up with more convincing arguments as well.
$endgroup$
– peterh
8 hours ago
add a comment |
$begingroup$
There won't be spin - impulse moment conserves also in the GR. There would be gravitational wave emission, although much smaller and a very different characteristic than the currently observed ones. The time of the full merge will be calculable by a GR free-fall.
$endgroup$
– peterh
8 hours ago
$begingroup$
Why would it be much smaller @peterh? If the two BH were moving in polar opposite directions in a head-on collision, wouldn't there be a large wave since all that momentum just... stops? There'd have to be a release of energy somewhere.
$endgroup$
– KGlasier
8 hours ago
1
$begingroup$
No. The black holes are modelled as point-like masses, with an event horizon around them. The gravitational waves are coming from the event horizons, more exactly from the space around the event horizons. No one knows, what will happen if the point-like masses collapse, because the current science stops far before that. What is known, are the known conservation laws of the GR. These don't predict very big things. However, I am just an educated layman. Hopefully a professional will come up with more convincing arguments as well.
$endgroup$
– peterh
8 hours ago
$begingroup$
There won't be spin - impulse moment conserves also in the GR. There would be gravitational wave emission, although much smaller and a very different characteristic than the currently observed ones. The time of the full merge will be calculable by a GR free-fall.
$endgroup$
– peterh
8 hours ago
$begingroup$
There won't be spin - impulse moment conserves also in the GR. There would be gravitational wave emission, although much smaller and a very different characteristic than the currently observed ones. The time of the full merge will be calculable by a GR free-fall.
$endgroup$
– peterh
8 hours ago
$begingroup$
Why would it be much smaller @peterh? If the two BH were moving in polar opposite directions in a head-on collision, wouldn't there be a large wave since all that momentum just... stops? There'd have to be a release of energy somewhere.
$endgroup$
– KGlasier
8 hours ago
$begingroup$
Why would it be much smaller @peterh? If the two BH were moving in polar opposite directions in a head-on collision, wouldn't there be a large wave since all that momentum just... stops? There'd have to be a release of energy somewhere.
$endgroup$
– KGlasier
8 hours ago
1
1
$begingroup$
No. The black holes are modelled as point-like masses, with an event horizon around them. The gravitational waves are coming from the event horizons, more exactly from the space around the event horizons. No one knows, what will happen if the point-like masses collapse, because the current science stops far before that. What is known, are the known conservation laws of the GR. These don't predict very big things. However, I am just an educated layman. Hopefully a professional will come up with more convincing arguments as well.
$endgroup$
– peterh
8 hours ago
$begingroup$
No. The black holes are modelled as point-like masses, with an event horizon around them. The gravitational waves are coming from the event horizons, more exactly from the space around the event horizons. No one knows, what will happen if the point-like masses collapse, because the current science stops far before that. What is known, are the known conservation laws of the GR. These don't predict very big things. However, I am just an educated layman. Hopefully a professional will come up with more convincing arguments as well.
$endgroup$
– peterh
8 hours ago
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
Well the spin is easy. Your system has zero angular momentum, so the spin will be zero.
I think there will also be no gravitational radiation. for the slightly technical reason that gravitational waves only come from changes to the quadrupole moment of a system and in your system the quadrupole moment is always zero.
So everything ends up in the final black hole which will have mass about 4.6 billion solar masses, coming from the mass of the two colliding holes, and their kinetic energy.
I'm not sure exactly how long the merger would last, but it will be comparable to the Schwarzschild radii involved, divided by $c$, so around three hours (as seen by a distant observer).
answered 7 hours ago
Steve LintonSteve Linton
3,9171 gold badge5 silver badges26 bronze badges
$endgroup$
$begingroup$
So the kinetic energy could end up adding more than double their combined mass, rather than radiate anything out? Does this mean that in theory we'd never be able to detect if this happened outside of maybe seeing the effect of a larger black hole to its surroundings?
$endgroup$
– KGlasier
7 hours ago
3
$begingroup$
@KGlasier I think that's right. It is worth noting that this scenario is unrealistic on at least three levels: more or less all black holes are spinning; it is unlikely they would collide exactly head on, rather than a bit offset; and supermassive black holes are not normally seen moving at 0.9c relative to anything much.
$endgroup$
– Steve Linton
7 hours ago
add a comment |
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$begingroup$
Well the spin is easy. Your system has zero angular momentum, so the spin will be zero.
I think there will also be no gravitational radiation. for the slightly technical reason that gravitational waves only come from changes to the quadrupole moment of a system and in your system the quadrupole moment is always zero.
So everything ends up in the final black hole which will have mass about 4.6 billion solar masses, coming from the mass of the two colliding holes, and their kinetic energy.
I'm not sure exactly how long the merger would last, but it will be comparable to the Schwarzschild radii involved, divided by $c$, so around three hours (as seen by a distant observer).
answered 7 hours ago
Steve LintonSteve Linton
3,9171 gold badge5 silver badges26 bronze badges
$endgroup$
$begingroup$
So the kinetic energy could end up adding more than double their combined mass, rather than radiate anything out? Does this mean that in theory we'd never be able to detect if this happened outside of maybe seeing the effect of a larger black hole to its surroundings?
$endgroup$
– KGlasier
7 hours ago
3
$begingroup$
@KGlasier I think that's right. It is worth noting that this scenario is unrealistic on at least three levels: more or less all black holes are spinning; it is unlikely they would collide exactly head on, rather than a bit offset; and supermassive black holes are not normally seen moving at 0.9c relative to anything much.
$endgroup$
– Steve Linton
7 hours ago
add a comment |
$begingroup$
Well the spin is easy. Your system has zero angular momentum, so the spin will be zero.
I think there will also be no gravitational radiation. for the slightly technical reason that gravitational waves only come from changes to the quadrupole moment of a system and in your system the quadrupole moment is always zero.
So everything ends up in the final black hole which will have mass about 4.6 billion solar masses, coming from the mass of the two colliding holes, and their kinetic energy.
I'm not sure exactly how long the merger would last, but it will be comparable to the Schwarzschild radii involved, divided by $c$, so around three hours (as seen by a distant observer).
answered 7 hours ago
Steve LintonSteve Linton
3,9171 gold badge5 silver badges26 bronze badges
$endgroup$
$begingroup$
So the kinetic energy could end up adding more than double their combined mass, rather than radiate anything out? Does this mean that in theory we'd never be able to detect if this happened outside of maybe seeing the effect of a larger black hole to its surroundings?
$endgroup$
– KGlasier
7 hours ago
3
$begingroup$
@KGlasier I think that's right. It is worth noting that this scenario is unrealistic on at least three levels: more or less all black holes are spinning; it is unlikely they would collide exactly head on, rather than a bit offset; and supermassive black holes are not normally seen moving at 0.9c relative to anything much.
$endgroup$
– Steve Linton
7 hours ago
add a comment |
$begingroup$
Well the spin is easy. Your system has zero angular momentum, so the spin will be zero.
I think there will also be no gravitational radiation. for the slightly technical reason that gravitational waves only come from changes to the quadrupole moment of a system and in your system the quadrupole moment is always zero.
So everything ends up in the final black hole which will have mass about 4.6 billion solar masses, coming from the mass of the two colliding holes, and their kinetic energy.
I'm not sure exactly how long the merger would last, but it will be comparable to the Schwarzschild radii involved, divided by $c$, so around three hours (as seen by a distant observer).
answered 7 hours ago
Steve LintonSteve Linton
3,9171 gold badge5 silver badges26 bronze badges
$endgroup$
Well the spin is easy. Your system has zero angular momentum, so the spin will be zero.
I think there will also be no gravitational radiation. for the slightly technical reason that gravitational waves only come from changes to the quadrupole moment of a system and in your system the quadrupole moment is always zero.
So everything ends up in the final black hole which will have mass about 4.6 billion solar masses, coming from the mass of the two colliding holes, and their kinetic energy.
I'm not sure exactly how long the merger would last, but it will be comparable to the Schwarzschild radii involved, divided by $c$, so around three hours (as seen by a distant observer).
answered 7 hours ago
Steve LintonSteve Linton
3,9171 gold badge5 silver badges26 bronze badges
answered 7 hours ago
Steve LintonSteve Linton
3,9171 gold badge5 silver badges26 bronze badges
answered 7 hours ago
Steve LintonSteve Linton
3,9171 gold badge5 silver badges26 bronze badges
answered 7 hours ago
Steve LintonSteve Linton
3,9171 gold badge5 silver badges26 bronze badges
3,9171 gold badge5 silver badges26 bronze badges
$begingroup$
So the kinetic energy could end up adding more than double their combined mass, rather than radiate anything out? Does this mean that in theory we'd never be able to detect if this happened outside of maybe seeing the effect of a larger black hole to its surroundings?
$endgroup$
– KGlasier
7 hours ago
3
$begingroup$
@KGlasier I think that's right. It is worth noting that this scenario is unrealistic on at least three levels: more or less all black holes are spinning; it is unlikely they would collide exactly head on, rather than a bit offset; and supermassive black holes are not normally seen moving at 0.9c relative to anything much.
$endgroup$
– Steve Linton
7 hours ago
add a comment |
$begingroup$
So the kinetic energy could end up adding more than double their combined mass, rather than radiate anything out? Does this mean that in theory we'd never be able to detect if this happened outside of maybe seeing the effect of a larger black hole to its surroundings?
$endgroup$
– KGlasier
7 hours ago
3
$begingroup$
@KGlasier I think that's right. It is worth noting that this scenario is unrealistic on at least three levels: more or less all black holes are spinning; it is unlikely they would collide exactly head on, rather than a bit offset; and supermassive black holes are not normally seen moving at 0.9c relative to anything much.
$endgroup$
– Steve Linton
7 hours ago
$begingroup$
So the kinetic energy could end up adding more than double their combined mass, rather than radiate anything out? Does this mean that in theory we'd never be able to detect if this happened outside of maybe seeing the effect of a larger black hole to its surroundings?
$endgroup$
– KGlasier
7 hours ago
$begingroup$
So the kinetic energy could end up adding more than double their combined mass, rather than radiate anything out? Does this mean that in theory we'd never be able to detect if this happened outside of maybe seeing the effect of a larger black hole to its surroundings?
$endgroup$
– KGlasier
7 hours ago
3
3
$begingroup$
@KGlasier I think that's right. It is worth noting that this scenario is unrealistic on at least three levels: more or less all black holes are spinning; it is unlikely they would collide exactly head on, rather than a bit offset; and supermassive black holes are not normally seen moving at 0.9c relative to anything much.
$endgroup$
– Steve Linton
7 hours ago
$begingroup$
@KGlasier I think that's right. It is worth noting that this scenario is unrealistic on at least three levels: more or less all black holes are spinning; it is unlikely they would collide exactly head on, rather than a bit offset; and supermassive black holes are not normally seen moving at 0.9c relative to anything much.
$endgroup$
– Steve Linton
7 hours ago
add a comment |
KGlasier is a new contributor. Be nice, and check out our Code of Conduct.
KGlasier is a new contributor. Be nice, and check out our Code of Conduct.
KGlasier is a new contributor. Be nice, and check out our Code of Conduct.
KGlasier is a new contributor. Be nice, and check out our Code of Conduct.
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$begingroup$
There won't be spin - impulse moment conserves also in the GR. There would be gravitational wave emission, although much smaller and a very different characteristic than the currently observed ones. The time of the full merge will be calculable by a GR free-fall.
$endgroup$
– peterh
8 hours ago
$begingroup$
Why would it be much smaller @peterh? If the two BH were moving in polar opposite directions in a head-on collision, wouldn't there be a large wave since all that momentum just... stops? There'd have to be a release of energy somewhere.
$endgroup$
– KGlasier
8 hours ago
1
$begingroup$
No. The black holes are modelled as point-like masses, with an event horizon around them. The gravitational waves are coming from the event horizons, more exactly from the space around the event horizons. No one knows, what will happen if the point-like masses collapse, because the current science stops far before that. What is known, are the known conservation laws of the GR. These don't predict very big things. However, I am just an educated layman. Hopefully a professional will come up with more convincing arguments as well.
$endgroup$
– peterh
8 hours ago