Questions tagged [black-hole]

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

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How can a singularity rotate?

So I've heard that all black holes that have been observed rotate to some degree. But if it has zero radius, how is it even possible for the black hole itself to be spinning? Or is it just all the ...
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What if the two Black Holes spiraling around each other are evaporating via their Hawking radiation?

A non-technical explanation In a Gravitational Wave event, the point is that in this event when Black Holes are spiraling around each other, they will cause the very fabric of Space-time to ripple and ...
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Why did the big bang not just produce a big black hole?

Questions I've often wondered about: If all the matter and energy were concentrated at a single point at the big bang, why wasn't that a black hole, or why didn't it form one? If the reason #1 above ...
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Black Hole Collision & Gravitational Waves

The Gravitational waves detected by LIGO on 14th September 2015 are attributed to a collision of two black holes, which had been rotating near the speed of light around each other just before the ...
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If any object could become a black hole, could any object become a neutron star?

A black hole doesn't necessarily need to form from a star; theoretically, it could form from any extremely dense object. In fact, many astronomers differentiate certain black holes, like supermassive ...
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Is the angular size of the black hole in the movie “interstellar” completely overblown?

I assume everybody is tired of reading questions derived from the movie Interstellar, I will try to keep this short and simple: In general in movies, in order to have stunning visuals, celestial ...
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Was our Universe born inside a Black Hole [duplicate]

Is there any possibility that our Universe was just born inside a Black Hole? If so, then mathematically prove that it happened and if it didn't happen, then please mathematically disprove it.
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Ramifications of black hole stellar system

Recently, I got around to seeing the movie Interstellar. In it, the characters of the movie visit a stellar system that appears to be built around a black hole instead of a star. On top of this, their ...
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What methodology should be used to choose the correct model for origin of QPOs in X-ray astronomy?

In X-ray astronomy, quasi periodic oscillations (QPOs) are routinely shown by black hole and neutron star X-ray binary systems in their X-ray flux. Despite being strong and easily measurable signals, ...
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A camera and time dilation?

If I travelled near a black hole, my time would progress slower relative to someone on Earth. This is clear enough. However, what if we sent a probe with a camera to a black hole? When we watch the ...
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Why doesn't the black hole in the center of the Milky Way glow similarly to the famous M87 image?

The M87 image made some astronomers famous recently as the first image of a black hole. In the Milky Way, it has been concluded that there must be a black hole due to the movement of stars near the ...
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Matter falling into a black hole [duplicate]

Watching a science show, I was told that if I watch matter falling into a BH, I'd never see it crossing the event horizon due to time dilation (or rather, it will take more time than the universe ...
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Will the Sagittarius A* Black Hole eventually swallow the entire Galaxy?

In one of his interviews, Sir Roger Penrose mentioned that when the Milky Way and the Andromeda galaxies eventually "collide" and merge into one, their super-massive black holes will also ...
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Can two singularities combine into one? [duplicate]

We know that black holes can collide and merge, but if they each have a singularity at the core, how can the two singularities merge and become one? Wouldn't the mere fact of a second singularity in ...
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1answer
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Does a kilonova leave a high mass remnant?

My understanding of Type Ia supernovae is that they are expected, in most cases, to destroy the white dwarf(s) that went in to them, leaving behind no high density remnants (i.e. no white dwarf, ...
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How do dark stars form?

I'm not referring to a star made of dark matter or a Newtonian dark star. I'm talking about a star powered by dark matter annihilation. I imagine it would form close to the centers of galaxies where ...
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Is this a Black Hole?

While researching about galaxies in Google sky, I came upon a strange area. Co-ordinates: 11h 6m 15.0 seconds | -77° 22' 9.8" A lot of space around this body is empty, is it possible that the ...
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Parent stars of our Sun - Where are its remains?

This is in a way related to this question. Question is: Our star is third generation star, which is explained by existing Barium. That Barium was created by other stars. Now, those stars must have ...
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Catalogue of black holes

Where can one find a reliable list of black holes that have been discovered/observed so far, directly or indirectly, along with their properties, like mass, spin, etc.?
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Does this black hole mass/galaxy stellar mass relation hold for extremely low-mass galaxies?

I read a preprint last week (Palmese & Conselice 2020) that suggested that the recent gravitational wave detection GW190521 could be the end result of a merger of two extremely low-mass galaxies. ...
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Are black holes considered part of baryonic content of universe?

Are black holes (like those detected by LIGO, for instance) part of baryonic content of universe or part of dark matter? Why?
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Can any information leave a black hole?

Referring to this question, is there any information that can leave black holes? Are they causing a permanent information loss in our Universe?
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Can our Sun become a black hole

Does every star become a black hole? Is there any probability that our sun can become a black hole? If yes then is it on its way to become a black hole? what is the current state of sun as per the ...
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Can an event horizon form with the observer already inside?

I am on a planet orbting a star around the center of the milky way (assume no supermassive blackhole there). By some mechanism, mass starting from the outer part of the galaxy gets pushed inward until ...
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What would happen on earth if there was a surge in gravitational waves [duplicate]

There are claims that when massive objects merge some of their mass is converted to gravitational energy. Such as the following links: https://astronomy.stackexchange.com/a/38727/2305 https://youtu.be/...
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GW190521 black hole merger total mass calculation and missing mass, how does this happen?

I have just read an article about that black hole merge event (it's in Italian): Sette miliardi di anni fa, due mostri si unirono What made me curious is that the article tell that a 66 solar mass ...
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Why isn't IMBH candidate GW190521 very “chirpy”? Which types of events will produce the most chirp-like behavior?

The first gravitational wave observations were noted for their "chirp-like" behavior; the objects would speed up as they got closer, radiating more strongly and therefore loosing energy ...
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How does hawking radiation work without virtual particles?

How does hawking radiation work without the existence for virtual particles? I read that certain quantum fields are distorted when a black hole forms on top of them. But what fields specifically? If ...
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How do accretion disks around black holes evaporate via winds?

I'm curious as to how accretion disks around black holes evaporate. I've heard winds play a crucial role in this. But what winds specifically and how do they form? Is it a stellar wind of sorts? If so ...
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What is the actual visual characteristics of a black hole?

Is there a safe distance in which a black hole can be observed with the human eye? What is a safe distance? I have seen many computer simulated and artist renditions, and I am not sure if they ...
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How String Theory calculates the Entropy of the Black Hole in a Background dependent way?

How does string theory get an agreement to the Hawking-Bekenstein equations to calculate the quantum entropy of a black hole in a background dependent way? Is there any sort of area parameter in ...
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Can Axions escape the Black Holes?

I read about Tachyons and Gravitational Waves and also about Exotic matter, really nothing can escape a Black Hole, can Axions escape for providing a new hope?
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Does blackhole merging break their event horizon segregation?

So far as I know, if we have 2 blackholes A and B, both having their own event horizons, then what's inside the event horizon of A remains completely unknown to us, and same for what's inside the ...
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Black Hole - energy and matter

Can someone explain what is happening with energy (e.g. light) and matter which was collected by a black hole? I suppose that matter builds a black hole's mass and size, but what about light? Does it ...
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How does gas in accretion disks of supermassive black holes create orbital torques on smaller black holes within the disks causing them to migrate?

This answer to What enhances the capture and merge rates of pairs of small black holes orbiting around supermassive black holes? links to Migration Traps in Disks Around Supermassive Black Holes which ...
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Have I nearly found the event horizon of a black hole?

The calculator on the website https://planetcalc.com/1758/ cites Wikipedia's Gravitational acceleration and implements: $$g = G \frac{M}{(R + h)^2}$$ For a black hole with mass $M$ equal to 5 solar ...
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How do OGLE-III and GAIA measure the mass of free microlensing black holes?

What is the "hypothesized lower mass gap" between 2.5 and 5 solar masses? eventually links to Constraining the masses of microlensing black holes and the mass gap with Gaia DR2. The angle of ...
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How many solar masses is the central black hole in the Whirlpool Galaxy?

I am having trouble finding the mass of the central black hole in the Whirlpool Galaxy M51a/NGC5194, it is stated that its companion galaxy NGC5195 has a supermassive black hole at its centre that is ...
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Is there or will there be any search after a primordial black hole 500 au from the Sun?

Since 2019 it is proposed that the hypothetical Planet IX may in fact be a primordial black hole. Black holes are being looked after differently than planets. You can look for a gravitational lens or ...
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If Planet Nine is a primordial black hole could it explain 'Oumuamua and Borisov's orbits without them being interstellar?

There has been an increasing amount of interest in the possibility of primordial black holes and that Planet Nine may be one itself. Planet Nine is a potential explanation for the orbital ...
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Charged black holes selective eaters

We have a charged black hole which is negatively charged. For this simple case the black hole is not rotating. If a negatively charged particle approaches the singularity the electromagnetic repulsion ...
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Spinning black holes acting as a slingshot

Could we use spinning black to act as a skyhook giving us enough energy boost to travel the galaxy?
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How can black holes spin if they're singularities? [duplicate]

How can black holes spin if the event horizon isn't a surface but just the border between where light can escape and where it can't? A black hole is assumed to be a singularity or the "entrance&...
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Velocity of ringularity

How fast is a ringularity1 spinning? Spinning black holes are created from spinning stars. The angular momentum of the 'parent' star must be conserved so spinning black holes are spinning much much ...
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Could a near collision with small black hole account for the effects of the 9th planet?

Much interest has been raised about the existence of a 9th planet. One reason for this is the strange orbits of bodies in the outer solar system. Could the orbits be explained by a near collision of a ...
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How much damage would collision with a similar mass primordial black hole do to earth?

All this talk of Planet 9 perhaps being a primordial black hole (PBH) made me wonder how dangerous a PBH collision with earth would really be. Specifically, if earth collided with a PBH of 1 earth ...
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Mathematical Analysis of Blackhole

Mathematically, for black holes old enough that the stellar material has collapsed all the way into the singularity, the region between the horizon and the singularity is occupied by a spacetime where ...
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How does neutron star collapse into black hole?

We know the spectacular explosions of supernovae, that when heavy enough, form black holes. The explosive emission of both electromagnetic radiation and massive amounts of matter is clearly observable ...
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What is the “hypothesized lower mass gap” between 2.5 and 5 solar masses?

Searching here for "mass gap" yields nothing yet. Penn State's Black hole or neutron star? LIGO-Virgo scientists find mystery object in 'mass gap' begins: When the most massive stars die, ...
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Does a merging massive binary black hole ‘emits’ more than one gravitational wave?

If we want to use gravitational waves (GW) to determine the Hubble constant, we need to find the source in the electromagnetic spectrum (EMS). However, we need to be lucky to ‘see’ it simultaneously ...

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