What is at the center of a galaxy?

Basically the thing at the center of the galaxy doesn't have enough of a gravitational pull to keep the entire galaxy in orbit, in the first place.

So, all galaxies SHOULD be breaking apart, with all the stuff in between should be flying off into deep space. But that clearly doesn't happen. Meaning there has to be some "matter" in between with enough gravitational influence that holds the galaxy together.

TL;DR: It's the "gravity rope" that keeps galaxies together.

Spin power

>What is at the center of a galaxy?
Black holes and the like.
>How does it have such a gargantuam gravitational power that it keeps billions of stars and other celestial bodies trillions of kilometers away in it's orbit?
It doesn't. They mostly keep each other in orbit.

>we don't know therefore an invisible force is there that will make our theory true

yep, we're back at square one

But shouldn't the dark matter be all at the center of the galaxy for this to work?

>What is at the center of a galaxy?

Sagittarius A*, a supermassive Black Hole 25,640 light years away from us and 4.1 million times the mass of Sol

>How does it have such a gargantuam gravitational power that it keeps billions of stars and other celestial bodies trillions of kilometers away in it's orbit?

Dark Matter

>What is at the center of a galaxy?

Well, the center of our galaxy is Sagittarius A*

>Sagittarius A*, a supermassive Black Hole 25,640 light years away from us and 4.1 million times the mass of Sol
do you have actual proofs or it's just someone s fantasy?

It's scientific fact. There's no real evidence for it, but it is scientific fact.

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If that were the case, we'd simply have an EMSMBH (Even More SuperMassive Black Hole) (N.B. Not actual scientific name)
I may be wrong here, but I am pretty certain that the idea comes from the edges of the galaxy spinning so quickly that it would tear itself apart. Thus, if we had DM spread out over an even larger volume than the galaxy itself, providing a larger pull towards the centre without affecting gravitational interaction at short ranges (much).

TL;DR it's much bigger than the galaxy

DM is theorized to be a massive substance that only interacts through the gravitational force (i.e. Not electromagnetic, not strong nuclear, not weak nuclear) and thus is "invisible" to other attempts to detect it. In theory it would bend light with gravitational lensing, but as we see no evidence of this it adds validity to the disperse theory of DM. Theorists of DM boil into 2 categories WIMPs (Weakly interacting Massive Particles) and MACHOs (MAssive Compact Halo Objects).

TL;DR DM is stuff that we either can't or can barely see.

I very nearly posted Weakly Interacting Massive Panties.

Your comment got me thinking about the masses of Sagittarius a* and the Milky way:
Sagittarius a* - 4 million solar masses
Milky Way - 5.8*10^11 solar masses

That is many times greater than the black hole, why aren't they in a unstable binary orbit?

Are we being raided by /pol/?

Supermassive black hole.
Actually, fairly small as SBHs go (compared to some seen in other galaxies) and it doesn't hold our galaxy together.
But we can see stars close to the centerpoint whirling about something massive at goodly fractions of lightspeed. They move visibly in photos taken months or years apart. Given that they're 33,000 light-years distant, that means they're really hustling!

You wouldn't want all the dark matter to be at the center of the galaxy. You may know that a hollow sphere exerts no net gravitational force on objects within it.
The orbits of stars are only affected by matter closer to the center-of-rotation than they are. I stellar velocities at various distances from the core (as measured by Doppler effect) were only due to the visible suns and dust, the rotation curve would have a particular shape; i.e. velocities would fall off steadily towards the outskirts. Stars near the rim should just crawl if most of the mass was in the central core. That's not what we see. Velocities become almost constant. It indicates that a large amount of unseen mass is distributed throughout the entire disc.

As stated in and elsewhere, the SBH isn't holding the galaxy together. It's only effects are the rapid circling of nearby stars (a few light-years) and the X- and gamma- radiation given off by the accretion disk of infalling matter. And it's not being "fed" regularly or our galaxy would have immense jets blowing out along the axis of rotation.

If Dark Matter is somehow proven to exist one day, how would that change physics as we know it today?

How would that change space exploration?

We know Sagittarius A* exists because we can detect emissions coming from the center of the Milky Way. And we know it is a black hole because we can observe nearby stars orbiting around it.

At the center of the galaxy there is not a black hole. It is said that ice giants protect a land of Fortnite and Ugandan armies. Stop listening to whatever crap your teacher tells you

Can we run into Dark Matter?
How does it interact with things without being seen?
How can we not detect it with all the stuff we've made to detect insignificant things (like gravity waves and whatnot)?

Is it stupid to think that maybe instead of a force pulling them inward there is a force pushing them in to where the innermost stars and planets and other forces of mass have no way of escape but to indefinitely push away from another force so it wouldn't collapse?
So the outermost masses are preventing escape outward but not in a line which they orbit, while all outer masses are very slowly pushing away into space as there is nothing holding them in.
The creation of the universe in the cosmos started small, in relation to its current infinite size, and expanded, and now we're waiting as it continues to expand.

When you run into things -- you bang your fist on the desk, for example, the electron clouds of the desk atoms are repelling the electron clouds of your hand atoms. Except for gravitation, electromagnetism is the only force we experience in everyday life.
Dark matter (assuming it's not baryonic matter, not made of protons and neutrons) isn't supposed to interact with electromagnetism. So you can't touch it. And because it doesn't interact with electromagnetism, you can't see it. That's why it's dark. (Bad name, but we're stuck with it now.) If it doesn't emit light, reflect light, or hinder light passing through it, it's invisible.
The only force which Our stuff and Dark stuff share is gravitation.
Think about neutrinos. They feel neither electromagnetism nor the strong nuclear force. They go through you, through the Earth, through several lightyears of solid lead as if they weren't there. Occasionally, they interact with the weak nuclear force, so we can spot one out of every zillion which pass through our detectors. Dark matter will be as hard, or harder, to find.
Gravity waves were detected because certain rare events (colliding neutron stars or black holes) briefly create staggering amounts of them. Judging by the way dark matter influences the orbits of stars, it's not especially concentrated in any one spot. Even if it outmasses all the stars in a galaxy, a galaxy is still pretty big, and if we COULD touch the dark matter, it'd likely still be a pretty good vacuum insofar as density goes.

If there was a repulsive force "constraining" the stars in a galaxy, the particles exerting that force would feel a reaction and be shoved outwards. They wouldn't "clump". They'd diffuse away into the space between galaxies.
But dark matter acts as if it's concentrated within galaxies.

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This might help if the former answers weren't sufficient:
youtube.com/watch?v=32qqEzBG9OI

The dark matter thing reminds of a book I read years ago called the capacitance theory of gravity. Written by some crazy old physicist.

Basically the guy says with regards to dark matter is that the more space, the more capacitance, so the more gravity. Vacuum having a pretty good k value in itself.

there is a fascinating documentary on the astronomer whose name i forget who spent a lifetime charting the orbit of stars around the center of the galaxy to show that there must be a supermassive black hole

I dont think it was a Nova show but something like that, either PBS or BBC I think

It might be on TPB

it was really good, gave one a feel for doing real science and the joy of real discovery

maybe this one?:

pbs.org/wgbh/nova/space/monster-milky-way.html

Participants

Eric Becklin
UCLA personnel.physics.ucla.edu/directory/faculty/index.php?f_name=becklin
Gregory Benford
University of California, Irvine
Neil deGrasse Tyson
Astrophysicist, American Museum of Natural History www.haydenplanetarium.org/tyson/profile/bio
Tiziana Di Matteo
Carnegie Mellon University web.phys.cmu.edu/~tiziana/
Reinhard Genzel
Max-Planck Institute, Garching
Andrea Ghez
UCLA www.astro.ucla.edu/~ghez/
Andrew Hamilton
University of Colorado casa.colorado.edu/~ajsh/
Brian McNamara
University of Waterloo
Steve Ritz
NASA Goddard Space Flight Center lheawww.gsfc.nasa.gov/~ritz/
Antony A. Stark
Harvard-Smithsonian Center for Astrophysics cfa-www.harvard.edu/
Kip Thorne
California Institute of Technology

No, what holds them on orbit are themselves, not center of the galaxy!

>because we can detect emissions coming from the center of the Milky Way
how do you know where is the center of milky way?
how do you know this is "emission" from the imaginary "black hole"?

this is all nothing but fantasies.

It's that "thing" propagates troughs those celestial bodies from one to another.

Eric Becklin:

sofia.usra.edu/sites/default/files/Menten_Eric_Becklin-pioneer_of_infrared_astronomy.pdf

>A supermassive blackhole
Nice phantasmagory.

A monkey named Steve