Questions tagged [supermassive-black-hole]

Questions regarding the most massive examples of black holes that typically reside at the centers of galaxies.

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Is the appearance of accretion disks of M87 and Sgr A* in EHT image, related to the nucleus being active or non-active?

I'm a newbie in this field so forgive me if I'm considering things wrong. As much as I can see, the newly published image of the Sgr A* looks pretty much the same as M87 released years ago. I'm ...
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10 votes
2 answers
864 views

Why is the ring in this simulation of Sgr A* off center?

In the recent releases of images of Sgr A*, simulated versions of what they expected were included along side the actual images they were able to get. What confuses me about these simulated images (...
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26 votes
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Why do some supermassive black holes have a * in their name?

Sgr A*, M87*,... Several supermassive black holes (SMBHs) at the center of galaxies have a star (*) in their name. But many others do not. Is there a physical difference between the SMBHs that are ...
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Can the Universe itself be a black hole? [duplicate]

Can the Universe be a Black Hole? Many years ago, after reading a book by Isaac Asimov (not a novel, but I forgot the title) I started wondering if it is be possible that the Universe itself is a ...
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2 votes
2 answers
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What is the reason for Hercules A to emit huge fountains of Plasma?

Hercules A, a supermassive-blackhole situated in the galaxy 3C 348, emits Plasma as far as 1.5 million light years away !! Although the cause is poorly understood, what could be the possible cause for ...
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5 votes
1 answer
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Have any HCSSs (supermassive black holes with a tight bunch of gravitationally bound stars) ever been detected?

This article from sciencealert states: Astronomers think these two galactic cores could merge into one larger black hole, sending huge gravitational waves rippling out across spacetime. But if there'...
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Image of the black hole [duplicate]

The first ever image of a black hole shows a circular black central portion surrounded by an illuminated accretion disk. If a black hole wraps spacetime completely around it, then in any direction it ...
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1 vote
2 answers
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Does the density of a black hole decrease after releasing a large amount of Hawking radiation?

Is is true that the smaller a 'regular', stellar-mass black hole is, the denser it is inside of its event horizon? After all, if you look up (or calculate) the Schwarzschild radii of the Sun and the ...
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Is gravity affected by time dilation? [closed]

I just thought about what time realy is but I can't put my head around this so I was thinking that if time dilation happens at the edge of a black hole that just everything gets slower. But does ...
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2 votes
2 answers
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Could quasars be interior to the event horizon of a SMBH?

My question is prompted by suspicion of three current ideas in astrophysics: GR predicts a singularity at the center of a BH without regard to QM. quasar hyper-luminosity is caused by an acretion ...
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Could a black hole's accretion disk be bright through natural means?

This question is based on this description of the Cormoran Supermassive Black Hole in the Orion Arm's website: Surrounding this event horizon is an (apparently artificial) accretion disk about 4AU in ...
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1 vote
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From where the light comes? [duplicate]

Gravitational field of a supermassive blackhole is so strong that even light cannot escape from it (eg. black hole in the core of M87). In this case when a blackhole tears a star,a bright disk of ...
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6 votes
1 answer
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Has gain in mass from accretion onto a black hole been observed?

Have we observed a black hole directly gain mass via accretion? That is, have we observed the black hole to have mass $m_1$ at time $t_1$ and then observed its mass to be $m_2 > m_1$ at a later ...
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7 votes
4 answers
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How can a black hole have a charge, or be charged?

So-called 'hairless' black holes (no-hair theory, or theorem?) , which is what real black holes are, can be described by just three characteristics: Mass, spin, and charge. It is easy enough to ...
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Why is the Milky Way's SMBH inactive?

Our galaxy is not an active galactic nucleus (AGN). With so many stars and so much gas orbiting it, as explained here Central kiloparsec of Seyfert and inactive host galaxies: a comparison of two-...
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Does black hole singularity really exists with respective to relative frame of reference? [duplicate]

How can one describe this phenomena? What are the factors that we should consider for solving such a problem?
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Can an entire star pass through the event horizon of a black hole unharmed?

Can there be any black hole big enough that a regular sized star can pass through its event horizon unharmed?
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1 vote
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What do stars in galaxies without supermassive black holes revolve around? [duplicate]

I still don't quite understand what the stars in galaxies without SBHs revolve around. I mean, the stars must orbit something. If the Sun suddenly disappeared, the planets wouldn't just continue in ...
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Could Sgr A* be a core of dark matter instead of a supermassive black hole?

A recent paper (related news) shows that Sgr A* at the center of the Milky Way galaxy could be a dark matter core, instead of a supermassive black hole, according to their calculation using the ...
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10 votes
3 answers
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How do we know that supermassive black holes can gain mass by means other than merging with other supermassive black holes?

I just stumbled across the following answer "update" from 2013: This just in, recent observations have ruled out the possibility that SMBHs gain mass only through merging with other black ...
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What is Hawking radiation? [closed]

Like the radiation the Sun gives out to sustain it's circular shape, will Hawking radiation sustain the black hole's shape?
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1 answer
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Would studying massive stars that are experiencing time dilation due to proximity to a black hole be useful?

I saw this question (Could a star closely orbit a black hole long enough for the star to have lost 0.5B+ years to time dilation?) and came up with an interesting thought. Massive stars live for less ...
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3 votes
1 answer
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Hypothetically, could a civilization in a solar system near a supermassive blackhole use the blackhole as a huge gravity lens telescope?

I have heard of various proposals that use the massive gravity of stars to sort of focus light at and observe with a suitable telescope placed at such a distance, and I am assuming here that bigger ...
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Is there a closest free-return trajectory to a black hole?

The scenario I am imagining is a test particle falling from infinity with an initial off-center velocity. In Newtonian mechanics the path would be a hyperbola. But I assume that, near a black hole, ...
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3 votes
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Do any particles in AGN jets escape the galaxy?

I have read, at http://www.thestargarden.co.uk/Black-holes.html for example, that whole stars can be ejected from certain galaxies. "These are thought to have been part of a binary star system ...
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30 votes
3 answers
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What keeps galaxies together?

The super massive black hole at the centre of Milky Way has a mass of about 4 million times that of our sun. Is this enough to keep the entire galaxy together, is it this black hole which keeps the ...
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How spaghettification is possible at the Event Horizon of a supermassive black hole?

if gravity is too strong then it will break a object apart as gravity is strong enough to break the chemical composition of object why we consider "Spaghettification" relevant in this case ?
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3 votes
3 answers
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Why don't black holes quickly eat up the galaxy/universe?

It's my understanding that the radius of the event horizon of a black hole is proportional to it's mass. Which means the surface area of a black hole is proportional to it's mass squared. Lets just ...
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What is the effect of extinction in the accretion disk for black hole mass determination?

I've created a basic model of the accretion disk (AD) by summing up blackbodies following the temperature profile of the AD according to Shakura & Sunyaev (1973) (extensively used in the ...
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17 votes
1 answer
3k views

How can a supermassive black hole be 13 billion years old?

A supermassive black hole was discovered recently that is 13 billion years old. This blackhole is 1.6 billion times the mass of the sun. How can this blackhole have formed so quickly after the big ...
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2 votes
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Why are galactic nuclei yellow?

So we've seen millions of galaxies, and all of them have a bright, yellow nucleus. What is the cause of the yellowness? Is it because of aging stars, redshift from the SMBH, or something else?
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3 votes
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What came first: Galaxies or Stars? [duplicate]

In Stephen Hawking's A Brief History Of Time, the book mentions that "in regions that were slightly denser than average...galaxies were born." (pg 123). However, according to many other ...
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8 votes
1 answer
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Why is there no color shift on the photo of the M87 black hole?

Last year, the first photo of a black hole in Messier 87 was published: (Source: EHT) It is quite obvious that about the lower half of the accretion disk is brighter. This question (or rather, the ...
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Details of the M87 Active Galactic Nucleus -- questions of scale

This video describes a scale model of the M87 SMBH (somewhat distorted to live in flat space and for other practical reasons) in which the Schwarzschild radius appears to be scaled to about 10cm, with ...
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Could blackholes warping space-time create dark energy?

I think the effects of blackholes on the surrounding space is localised to a small area around the blackhole but I wondered if the largest blackholes at the centre of massive clusters could be a ...
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3 votes
2 answers
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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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4 votes
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Will the first Event Horizon Telescope image of the Milky Way's black hole Sgr A* just be another lumpy orange donut?

@HDE226868's answer to Why doesn't the black hole in the center of the Milky Way glow similarly to the famous M87 image? explains that neither black hole is orange and any Event Horizon Telescope ...
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2 votes
1 answer
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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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9 votes
1 answer
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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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1 vote
1 answer
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Are there any predictions of what galaxies exist in the Norma cluster/ Abell 3267?

I am working on a map for a science fiction story and using what information is available I have a good idea of locations of nearby galaxy groups and clusters and where the known supermassive black ...
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3 votes
1 answer
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Would DCBH form supermassive stars first before BH formation

In reading some literature it seems ambiguous (intentionally?) as to the path that Direct Collapse Black Holes (DCBH) take. Some papers do talk about pristine Halos collapsing to form supermassive ...
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How do we know that the discovered M87 black hole isn't just a star surrounded by a dust disk?

To an untrained eye like mine, pictures of stars surrounded by dust discs look very much similar to the picture of the M87 black hole. Here are some pictures of these dust discs: And here is a ...
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2 votes
2 answers
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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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3 votes
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Why would the merger of spinning black holes within the accretion disk of a supermassive black hole cause them to "shoot straight up" out of the disk?

I just tried to read the new New York Times article Two Black Holes Colliding Not Enough? Make It Three which links to the new 25-June-2020 Physical Review Letter Graham et al. Candidate ...
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2 votes
1 answer
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What enhances the capture and merge rates of pairs of small black holes orbiting around supermassive black holes?

I just tried to read the new New York Times article Two Black Holes Colliding Not Enough? Make It Three which links to the new 25-June-2020 Physical Review Letter Graham et al. Candidate ...
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0 votes
1 answer
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What happens when a huge star is being consumed by a black hole

What happens when a huge star in its later stage( iron core) is near a black hole that slowly consumes some of the matter from the star? Would this offset the imbalance caused by iron fusion ...
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What will be the eventual result of the Milky Ways future mergers?

I am wondering, after the Milky Way merges with Andromeda and other near by dwarf galaxies and globular clusters, will it then merge with galaxies in the Virgo cluster and even Laniakea? And if so ...
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4 votes
1 answer
231 views

What is the actual temperature of a quasar?

My daughter asked me last night: What is the hottest thing in the universe? The first thing that sprang to mind was the core of a fresh neutron star (this question agrees: What is the hottest thing ...
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17 votes
2 answers
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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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3 votes
1 answer
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Hills' mechanism for making Hypervelocity Stars

In Hill’s mechanism, the gravitational tidal force of a single MBH disrupts an approaching binary. One star is captured on an eccentric orbit around the MBH and, by conservation of energy, the ...
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