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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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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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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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 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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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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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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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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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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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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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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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 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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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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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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How much mass per year may the black hole at the center of the Milky Way gain by capturing neutrinos?

If we are immersed in a sea of neutrino, then a black hole should be constantly capturing the ones crossing its event horizon, and gaining mass. How much neutrino mass falls inside a black hole per ...
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How much time passes in the outside universe when falling into a black hole?

If someone were to jump into a black hole, looking back at Earth, how far into the future would they see of Earth? As I understand it, time would dilate approaching infinity as you approach the event ...
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What is the Schwarzschild radius actually?

I am currently writing a detailed essay about black holes, the history of their discovery and their characteristics and I can't find the appropriate literature online and in my local libraries (I even ...
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Could the unseen companion of HR 6819 be a close binary system?

Recently there was an announcement of a black hole candidate in the HR 6819 system (ESO Instrument Finds Closest Black Hole to Earth). In the proposed system, the black hole forms a close binary ...
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Is it possible that some of the confirmed exoplanets are in fact primordial black holes?

Recently astronomers discovered a black hole lying just 1000 light-years from Earth, in a triple star system (HR 6819) that can be seen with the naked eye. This discovery has increased the possibility ...
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any proof that stars are born, and die?

I've heard from a lot of people that stars are "born" (usually from black holes), then grow bigger, then eventually "die" by some kind of supernova etc., but have any of these events actually been ...
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Radial velocity data in ALADIN or TOPCAT for Binary Systems

I just installed both, Aladin and Topcat VO tools. I want to know how to search for: HD 226868 and A0620-00 radial velocity data or photometric curves to derive the hidden black hole mass in those ...
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Objects falling in a black hole radiate their mass?

An object reaching the event horizon has almost infinite kinetic energy. When the total energy of the object surpasses the breaking energy of the electroweak field , the Higgs mechanism would stop ...
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Is the object a pulsar

We have a star having 1.8 solar mass. Justify any four means (measurable/ observed properties) by which you can identify that the object is a Pulsar and not a white dwarf or a Black Hole. So one ...
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A question regarding the evolution of black holes [duplicate]

It is known that for an outside observer who is stably outside the a black hole, never sees an object falling in go beyond the black hole. So does it mean that even though the mass of black hole ...
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Is it possible that it actually takes an infinite amount of time to reach the apparent horizon of a black hole?

I know a black hole can absorb matter and maybe also release Hawking radiation. I think that according to the Gullstrand–Painlevé coordinates, space is flowing and the apparent horizon is the region ...
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Why are pseudo-Newtonian potentials used in studies of accretion processes around black holes?

In accretion processes around black holes, pseudo-Newtonian potentials are defined for the the black hole geometry. For examples, the potentials defined by Paczynski-Wiita and Artemova et al. for ...
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Can one see a black hole?

Can one see a black hole on earth? If a black hole does not emit light, how can one take a picture of the black hole itself? There's some discussion that the image composed by the Event Horizons ...
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Is there work underway to push the long baseline capabilities of the Event Horizon Telescope to sub-millimeter wavelengths?

The Max Planck Institute for Radio Astronomy's press release Something is Lurking in the Heart of Quasar 3C 279; First Event Horizon Telescope Images of a Black-Hole Powered Jet shows a stunning ...
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Could we make “tiny black holes”? [closed]

To study the physics of black holes (What we presume as really dense matter) could we not simply simulate that here on earth? What if we took 1 hydrogen molecule and just crushed it with enough force ...
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If a black hole pulls every object in the universe, why there is a light around it?

I've seen some black hole images and I've seen some movies about it e.g(interstellar). I wonder why it has a light around it. Even if I know that light can't escape through it. Can someone enlighten ...
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What is the precession of the star S62? [closed]

What is the angle of precession of the star S62 orbiting the Milky Way supermassive black hole?
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Is there an upper limit on the mass of black hole mergers we can detect?

From the LIGO website, black hole mergers have been observed between black holes with a mass up to roughly 50 $M_\odot$. Are there no black holes with a mass above 100 $M_\odot$ or is this an ...
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How bright would Sagittarius A* be from Earth if it became an Active Galactic Nucleus?

Essentially I'd like to know how bright our central black hole could appear from earth in relation to full moon brightness. Assuming maximum energy output (like when it's gobbling up an entire ...
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How close would the sun have to get to a supermassive black hole to have Jupiter stripped and slingshot into interstellar space?

Please make whatever assumptions are needed. Assume sun approaches black hole on some sort of hyperbolic trajectory. Assume size of supermassive black hole is same as the one at center of our galaxy....
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When did it take place, and what was the cause of the first blackhole in the universe?

When did it take place, and what was the cause of the first back hole in the universe? Does this time precede stars collapsing as a result of old age?
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black Holes and Neutron Stars

if the universe is constantly expanding then the distance between black holes and neutron stars must be increasing. Then What makes them to come under the influence of each other's gravitational ...
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How does a supernova occur when a massive star collapses into a black hole?

My layman's understanding of a supernova explosion is that it's caused by a rebound when a massive star collapses. When the core collapses to a point where neutron degeneracy pressure dominates, the ...
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How fast does a spacecraft have to be to enter a primordial black hole without being torn apart?

If there really is a primordial black hole beyond the Kuiper belt, we can send a probe to the black hole and into it. But how fast must the probe be in order to enter the black hole without being ...
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Can the WISE telescope detect black holes?

Black holes are hot, aren't they? With its infrared scan, could the WISE telescope also detect a black hole? The hypothetical planet beyond the Kuiper belt could actually be a primordial black hole. ...
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Have we ever seen the formation of a blackhole?

So I know that the formation of a supernova has been observed and that we have taken images of blackholes, however, has the formation of a blackhole ever been observed. How do we observe it?
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Jet streams of black holes emit [duplicate]

The speed of light is the upper limit at which conventional matter can travel. However, jet streams propel "material (...) at a significant fraction of the speed of light" (Wikipedia). Let me ...
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What happens with the black hole's mass when a black hole disappears?

If a black hole isn't "fed" by attracted matter, it disappears someday. But how is that even possible? What happens with the mass at its singularity? It can't just disappear or am I wrong with ...
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What observational data convinced Stephen Hawking that Cygnus X-1 was indeed a black hole and caused him to break into Kip Thorne's office?

It's generally easier to be certain an object is a star than a black hole. HDE 226868 is one of our site moderators and a blue supergiant star. The latter has a 5.6 day companion that supplied a ...
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Why don't they make an image of the black hole in the M33 galaxy?

Since we see the Triangulum galaxy M33 from a quite vertical position (contrary to our Milky Way and a bit the Andromeda galaxy) it should be easy to image the black hole in the center of it, shouldn'...
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Can a black hole with the density of water exist?

During an outreach event, the speaker mentioned the fact that black holes weren't necessarily dense objects and that black holes of any density could exist, even black holes with the density of water. ...
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Why does Newtonian physics give the right radius for a black hole?

When computing the distance at which the escape velocity is equal to the speed of light, the result is equal to the Schwarzschild radius. Is this just a coincidence, or is there a physical reason why ...
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How far away are the events that caused the gravitational waves that have been detected?

A certain number of gravitational wave events have been detected. Is it possible to know how far away the mergers that caused those gravitational wave events are?
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Primordial black holes microlensing

Could the movement of a PBH found in the outer solar system by microlensing be totally unpredictable and impossible to track after it was first detected?

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