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Questions regarding points of extremely high mass density, which creates an extremely strong gravitational field from which light cannot escape.

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Has the Penrose process ever been linked to an observed phenomenon in some way?

This answer mentions the Penrose process as a potential mechanism that could change the axis of the orbital angular momentum of an accretion disk around a black hole away from the original axis of the ...
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0answers
54 views

Have we gotten a real photograph of a black hole? [duplicate]

I never heard the news that we got one but I think we really did and people just don't realize it so it didn't go into the news. I think the answer at Have we seen a black hole? is wrong. 43m11s into ...
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1answer
51 views

Star - Black Hole binary. Star core Collapses. Does the black hole immediately grow from neutrinos?

I was reading on how Type II Supernovae release as much as 99% of their energy as neutrinos. So I was thinking: suppose there was a large star and black hole binary system, but the two were not close ...
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1answer
44 views

Black Holes and Worm Holes [closed]

Can a Black Hole enter inside a Worm hole? If yes then what will a observer observe if it present at the another side of Worm hole?
4
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1answer
52 views

What defines the plane of an accretion disk around a black hole?

This may be a noob question, your patience is appreciated. The question Do we know at which angle the Event Horizon Telescope will look at the accretion disk of Sagittarius A*? about just how close ...
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1answer
65 views

Black-hole becoming a star again - follow-up question [closed]

Some questions have been posed about black holes becoming stars again once they attract enough hydrogen/atomic matter from another star. Some answers were a forceful NO. Never. However - let's ponder ...
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0answers
34 views

What fractions of matter are retained and displaced by quasars?

Following on from a query concerning quasar mass, what fraction of matter is ejected compared to matter that is lost to the BH? Is there a graph that describes the fractions of the mass of quasars ...
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1answer
72 views

Why is the Innermost Stable Circular Orbit (ISCO) of a non-rotating black-hole 3 times the Schwarzschild radius?

If anyone has a derivation of this result, it would be appreciated greatly.
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1answer
157 views

What is the actual black hole merger speed?

I have seen models of 2 black hole mergers. https://www.theverge.com/2017/11/16/16665132/gravitational-waves-ligo-virgo-black-holes-merger-multi-messenger-astronomy When we see a space ship appear ...
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3answers
184 views

Can “rogue” supermassive black holes be made this way?

Could two galaxies (one big and one small)intersect at a velocity to allow the smaller black hole to escape but not the galaxy around it?
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2answers
160 views

What is the fastest a galaxy or other body has been measured to (or can) travel?

Our solar system travels at an average speed of 515,000 mph and our galaxy at 1.3 million mph through space. What is the fastest moving body in space recorded and the fastest can a black hole or ...
5
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2answers
83 views

How do isolated binary compact systems survive their formational supernovae?

In a broad sense I'm trying to understand how a binary black hole or neutron star systems can form from isolated binary massive star systems (i.e., other than from migration within rich BH/NS clusters)...
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2answers
144 views

Will a black hole swallow the universe?

If black holes swallow stuff, will a big black hole eventually swallow the universe? The universe will eventually go dark, because there will not be enough matter to make stars, and all that will be ...
4
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3answers
117 views

Can a black hole be torn apart by SMBHs?

Suppose two SMBHs (supermassive black holes) are brought close (e.g. during a galactic merger). Suppose that a "normal" black hole drifts into the space between the SMBHs. Could the gravitational pull ...
1
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2answers
183 views

How loud would a black hole be?

If we could hear black holes, how loud would they be? I know that this is basically the same question as the question "How loud would the Sun be?", except this time there is a black hole. But since ...
3
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1answer
81 views

Can a stellar mass black hole swallow Earth?

In the Astronomy magazine I read that the stellar mass black holes are only the size of Rhode Island. Can they swallow Earth?
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1answer
74 views

Why smaller black holes are considered to be more dangerous than bigger black holes?

More massive the body is more is the gravity.Still often smaller black holes are considered to be very dangerous than the bigger ones,why?
4
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1answer
78 views

What does a black hole elements consists of

what are the elements of a black hole it just says what a black hole is? there must be elements that the sun consists of right?
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1answer
58 views

Physical measurements and celerity of black hole mergers?

LIGO detected a black hole merger for bh's of about 30 solar masses, with a schwartzchild radii of about 20km. Were the gravity waves generated by masses distanced by a few microns or a few ...
4
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2answers
78 views

Would LIGO Detect Head-On Collision?

Assume two black holes collide head-on. In other words, they were not orbiting one another before the collision. I know this is unlikely. Further assume that their sizes and distance from Earth are ...
5
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3answers
183 views

Why do neutron stars collide instead of just revolving around each other like planets revolve around the Sun?

We know about events like two neutron star colliding and resulting in a black hole, also collision of black holes, and collision of galaxies. But we never see a satellite such as a moon colliding with ...
11
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6answers
6k views

What will happen to the shape of a galaxy when a super massive black hole lying in its center dies(evaporates out)?

What's at the Center of the Milky Way? In this article it is said that a supermassive black hole lies in the center of milky way galaxy. At its center, surrounded by 200-400 billion stars and ...
8
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3answers
214 views

Why black holes are extremely cold?

"The most massive black holes in the Universe, the supermassive black holes with millions of times the math [sic] of the Sun will have a temperature of 1.4 x $10^{-14}$ Kelvin. That's low. Almost ...
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1answer
45 views

When black holes forms out of a supernova do they have a very high velocity?

When black holes forms out of a supernova do they have a very high velocity ?? Or do they remains at the position of parent star ??
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0answers
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Black holes the project stuff out of them? [duplicate]

I was wondering how can a black hole regurgitate anything from it. I have seen pictures or illustrations of a black hole having two point of stuff coming out. I always thought of a black hole ...
4
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3answers
132 views

Is star a necessary phase in black hole lifecycle?

It now seems general fact that when a massive star core collapses at the end of its lifecycle it forms a black hole, can a black hole be formed skipping the star phase altogether?
4
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1answer
79 views

Can a black hole undergo a Penrose process inside another black hole's ergosphere?

I recently watched this video on black holes: https://www.youtube.com/watch?v=ulCdoCfw-bY And that statement should give you an idea of my level of understanding :) I was wondering if a spinning ...
4
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2answers
107 views

Black Hole growth [duplicate]

The latest info on black holes with regard to their formation is that since space and time go to infinity at the event horizon, from an outside perspective nothing ever enters a black hole, and it ...
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2answers
125 views

Star formation around rotating black holes?

Please excuse an amateur question. While trying to think of anything but what was happening during a dental procedure my mind turned to a model of a star close to a rotating black hole and the ...
3
votes
3answers
131 views

Is there a possibility that a white dwarf can turn into a neutron star or a black hole?

I know that a white dwarf is mainly balanced by electron degeneracy pressure and that if it gains more than 1.4 solar masses from any source (such as a companion star or a collision), it explodes as a ...
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2answers
56 views

Information Paradox with Hawking's Radiation

A theory about Blackholes storing the information from the universe. Being said that Blackholes are condensed mass sufficient enough to break every particle into different elementary particles, ...
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3answers
48 views

Are black holes different sizes thanks to the different sized stars that created them? [duplicate]

If the point in space that belongs to the collapsed star (that formed the black hole) is infinitely dense, why are black holes different sizes? Is it due to them feeding on stars and everything else ...
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2answers
58 views

Strange behaviour of black holes [duplicate]

We know black holes emit streams of radiation ,also recently discovered that they emit visible light when they eat any nearby matter . "We find that activity in the vicinity of a black hole ...
3
votes
3answers
128 views

Theoretically what happens to a black hole that evaporates?

Theoretically, does an evaporating black hole remain a black hole until it evaporates to nothing? Or does it change into something else once it evaporates to below a certain mass?
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1answer
76 views

Why does kerr black holes have a ring shaped singularity rather than point?

I read about ring singularity on Wikipedia and didn't quite understand the flow of liquids inside a rotating body causing a ring shaped singularity with zero thickness. Moreover is it specifically ...
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2answers
175 views

Do black holes really exist?

Black holes from my knowledge are created from the collapse of a star’s own gravity crushing itself, Now my question is well two questions, is it really infinitely dense to where space-time can be ...
3
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1answer
178 views

Can a star eat a black hole?

I know there are stars much larger than the sun and that we've discovered "small" black holes, so, let's say that the Pistol Star, which is at least 80x the mass of the sun, and the smallest known ...
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2answers
93 views

How is the entropy of a blackhole stored at its horizon?

I read that a blackhole has an entropy that is given by the area of its event horizon (measured in Planck units). Does that mean that this information is actually physically stored there? If yes, how ...
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0answers
33 views

Can anything escape a black hole or not? [duplicate]

I'm not a professional astronomer or physicist, though the fields greatly interest me. Please keep this in mind if the following sounds like a stupid question. In virtually every documentary I've ...
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2answers
124 views

If a black hole has a mass of a universe what will be the volume of it?

Will it suck the entire universe in? What will the black hole look like to us, assuming we do not immediately get sucked in?
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1answer
88 views

Could gravitational waves near merging black holes collapse to a black hole themselves?

I have understood that merging black holes emit considerable amount of their mass as gravitational waves (up to 5-10%). Based on what I have understood from gravitational waves, the closer black holes ...
4
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1answer
149 views

Can light be trapped in orbit?

Could rays of light be ever trapped in a constant orbit around a black hole if approached from a certain angle ? Like light hitting a glass or liquid with critical angle.
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1answer
74 views

Can we detect a black hole's radiation?

Stephen Hawking proposed that a black hole emits radiation as it evaporates. Black holes don't let any radiation escape their event horizon because even particles with the speed of light get trapped ...
3
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1answer
172 views

Does Hawking radiation in fact bring mass into the universe?

As I understand virtual particles pairs, e.g. electron and positron spontaneously pop into existence for tiny period of time, then they annihilate. When virtual electron and virtual positron ...
3
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1answer
171 views

Has a “white hole” theory been advanced to explain anomalous star formation in Sagittarius A?

In 2008, the European Southern Observatory reported, upon the end of a 16-year study described here http://www.eso.org/public/usa/news/eso0846/, that the 28 stars nearest the very large black hole in ...
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1answer
86 views

Gravastar Star With no Horizon with ultracompact and very density possible?

Is that possible with some strange Quantum Effect could give rise to a completely new kind of a star? Gravastar(Gravitational Vacuum Star) an object hypothesized in astrophysics as an alternative to ...
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1answer
174 views

Coordinates of known black holes in our Galaxy (Milky Way)

There are some articles in wikipedia with the list of known (or candidates) black holes here and list of nearest black holes. Also there is a map of Milky Way. My question is where can I get ...
5
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2answers
190 views

Why is frequency different for gravitational waves coming from SMBHs vs small compact binaries?

Why do gravitational waves emitted by supermassive black holes binaries have low-frequency range (~10$^{-9}$ - 10$^{-2}$ Hz) than those emitted by stellar mass compact binaries (~10$^{-4}$ - 10$^2$ ...
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0answers
52 views

How does the size of a naked black hole effect its photon sphere?

What effect does the size of a black hole have on the size or density photon sphere and proximity to the horizon? If a person is in space looking at 2 black holes (one of them big and the other ...
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0answers
54 views

What would a black hole merger look like?

Ship 1 is out side the black hole. Ship 2 is nearing a black hole. To ship 1 it would appear that ship 2 would be moving slower to the point it would seem like ship 2 stopped moving the closer to the ...