Questions tagged [supermassive-black-hole]
Questions regarding the most massive examples of black holes that typically reside at the centers of galaxies.
194
questions
2
votes
3
answers
143
views
How can Kerr black holes have a 'speed limit' to how fast they can spin?
Obviously, the speed of light is a presumed limit, at least for 'physical' objects moving 'within' ('through'?) spacetime, but...
In recent news some scientists believe they have figured out the ...
- 4,891
-6
votes
0
answers
72
views
Is the largest black hole larger than the Solar System?
Yes. Ton-618 is the largest black hole, and if it was replaced with our solar system, it would reach far after the end of the solar system, which is called the Kuiper Belt. Ton-618 has a mass 66 ...
- 1
5
votes
1
answer
3k
views
What is a "Gentle Giant" Black Hole?
I have seen articles about the Milky Way's "gentle giant" black hole. For example:
https://nypost.com/2022/05/12/image-of-gentle-giant-black-hole-at-milky-ways-center/
https://www.reuters....
user52213
1
vote
1
answer
68
views
ER=EPR and information fuelling cosmic expansion
I apologize in advance for the lack of education, I'm a Canadian hillbilly.
I was considering the concepts of ER=EPR and the growth of the black hole's internal system with the addition of information ...
- 19
4
votes
2
answers
168
views
Is it possible to detect gravitational lensing of both light and gravitational waves originating from the same event?
Is it theoretically possible to detect gravitational lensing of both light and gravitational waves, when both originate from the same source/event (merger of two stellar black holes or merger of two ...
- 681
3
votes
1
answer
82
views
Could the revolution of super-massive black holes around each other create a pulsar-array gravitational wave signal despite 'final parsec' problem?
Some commentators on the recently-observed very-long-wavelength gravitational wave signal involving pulsars, like Dr. Becky Smethurst, have implied that it might not be merging supermassive black ...
- 4,891
1
vote
1
answer
144
views
Could macroscopic primordial black holes have created metals shortly after the big bang?
After seeing articles about the jwst like these two: https://news.cornell.edu/stories/2023/02/astronomers-discover-metal-rich-galaxies-early-universe
https://www.livescience.com/james-webb-space-...
10
votes
2
answers
2k
views
What is the mechanism through which mass is converted to thermal energy in the accretion disc of a black hole?
In the book The Cosmic Perspective, it is stated that as matter is falling into a supermassive black hole, up to $40\%$ of its mass are converted to thermal energy, making the accretion of matter ...
- 203
0
votes
1
answer
165
views
If black holes contain dark energy would the expansion of the universe be uniform?
Because black holes are different sizes presumably they would contain different quantities of dark energy and so some galaxies would accelerate faster in some directions than others.
Dark energy from ...
user51209
2
votes
1
answer
505
views
Did the Grus star get expelled from the Milky way because it was accelerated by the Sagittarius A black hole?
On Wikipedia there is an article that says a star may have been expelled from the Milky Way because it interacted with Sagittarius A.
Sagittarius A* from Wikipedia:
In July 2019, astronomers reported ...
user50918
1
vote
0
answers
49
views
Does the (relative) distance of the photon sphere from the center of a black hole vary according its mass?
I know that the photon circle or photon sphere is located at around 1.5 times the radius of the Schwarzschild event horizon, but wouldn't it be comparatively further out for smaller black holes?
After ...
- 4,891
6
votes
1
answer
543
views
What do the symbols signify in Dr. Becky Smethurst's radiation pressure equation for black holes?
In her most recent video, "An ULTRAMASSIVE black hole has been discovered in a BRAND NEW way!", as well as a previous video, "How massive can black holes get?", Dr. Becky Smethurst ...
- 4,891
1
vote
3
answers
110
views
How does Very Long Baseline Interferometry work?
According to internet sources, this technique increases the effective diameter of the telescope, thus improving the angular resolution of the telescope. However I don't understand how this actually ...
- 779
5
votes
1
answer
378
views
What's the meaning of "hard supermassive black hole binary"?
In this paper, the authors state in the Introduction that
A hard SMBHB [SuperMassive Black Hole Binary] can eject surrounding stars to transfer their orbital energy and angular momentum, which may be ...
- 2,404
10
votes
2
answers
1k
views
Could we detect dark matter by black holes gaining unexplained mass?
Dark matter is said to interact only gravitationally, so it won't commonly form black holes by itself. But if a black hole is already there, and dark matter encounters the event horizon, it should go ...
- 255
4
votes
1
answer
910
views
What is the rotational speed of Sagittarius A*?
Sagittarius A* is the Milky Way's own supermassive black hole. Up till recently, I used to think that Sagittarius A* was a static black hole, i.e. It had no rotational speed at all.
But after doing a ...
- 2,585
15
votes
7
answers
10k
views
How did the Milky Way quasar not disrupt life on Earth?
According to most sources of information I have found (A Quora answer and books), when galaxies become quasars, they destroy all life in their host galaxy, as they output so much radiation that they ...
- 2,585
3
votes
2
answers
182
views
Will the universe eventually merge completely into a single, enormous BH
I see other similar questions, but mine is more specific: If total merger into one BH is the ultimate endgame, then if the universe had no net angular momentum in the beginning, then wouldn't the ...
- 57
4
votes
0
answers
76
views
Do all black holes, including stellar-mass ones, rotate at nearly the speed of light? Also, what exactly does that do to their shape?
From what I understand, astrophysicists have known for almost a decade that supermassive black holes seem to spin at incredible velocities; nearly the speed of light... In fact, some of the outer ...
- 4,891
1
vote
0
answers
26
views
How many massive black holes exist in AGN-type galaxies?
Most galaxies have a massive (i.e., $m \gtrsim 10^5$ M$_{\odot}$) black hole in their center.
Is it known 1) theoretically and 2) observationally what fraction of these massive black holes (maybe as a ...
- 4,439
4
votes
1
answer
71
views
What could cause a wind from an SMBH
In this paper, the author tests whether the Milky Way's Fermi bubbles could have been caused by an AGN-type explosion, or by a 'wind'. He comes to the conclusion that the wind may be "the same as ...
- 2,404
3
votes
1
answer
88
views
How do I create well a weighted black hole mass function?
I'm running a set of simulations to study the evolution of Super Massive black holes.
In principle, I have the black hole masses and other property called merger tree weight in Mpc-3 unit which is ...
10
votes
1
answer
2k
views
Where is the barycenter of the Milky Way Galaxy?
Is the barycenter of the Milky Way Galaxy located within the supermassive black hole, or its event horizon, at the center of our galaxy?
- 1,447
3
votes
1
answer
112
views
Why were only 4 days of data used in the M87 EHT observation?
I wonder why only 4 days of data were used in the M87 Event Horizon Telescope (EHT) observation. What is preventing you from obtaining a more detailed and clearer image over a longer period of time?
- 109
2
votes
2
answers
61
views
What does "energy dumped into waves" mean?
In A Very Short Introduction: Black Holes by Katherine Blundell, the author discusses the merger of two black holes in a binary system:
The energy released in the merger of two supermassive black ...
- 239
1
vote
2
answers
121
views
Could primordial black holes explain the SMBH in the galactic centers?
If there were enough primordial black holes (with the right mass) they could explain dark matter. Could they explain the gargantuan monster holes in the center of galaxies?
- 1
3
votes
1
answer
120
views
Is the dark matter/baryonic matter ratio the same in galaxies with supermassive black holes?
My hypothesis is that if the ratio of dark matter/matter in galaxies with supermassive(weighing billions of suns) black holes are higher the black hole itself would be made of a large portion of dark ...
- 33
8
votes
1
answer
331
views
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 ...
10
votes
2
answers
917
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 (...
- 3,404
26
votes
3
answers
9k
views
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 ...
- 17.4k
1
vote
0
answers
71
views
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 ...
- 111
2
votes
2
answers
137
views
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 ...
- 2,610
5
votes
1
answer
121
views
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'...
- 681
0
votes
1
answer
80
views
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 ...
- 911
2
votes
2
answers
146
views
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 ...
- 4,891
0
votes
2
answers
171
views
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 ...
2
votes
2
answers
140
views
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 ...
- 29
5
votes
3
answers
1k
views
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 ...
- 383
1
vote
0
answers
36
views
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 ...
- 2,610
6
votes
1
answer
238
views
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 ...
- 4,439
11
votes
4
answers
5k
views
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 ...
- 4,891
7
votes
1
answer
300
views
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-...
- 2,404
-2
votes
2
answers
143
views
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?
10
votes
2
answers
3k
views
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?
- 263
1
vote
0
answers
35
views
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 ...
- 145
4
votes
1
answer
233
views
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 ...
- 593
10
votes
3
answers
2k
views
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 ...
- 31.4k
-1
votes
1
answer
79
views
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?
- 11
2
votes
1
answer
74
views
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 ...
- 6,613
3
votes
1
answer
101
views
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 ...
- 503