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  4. What is the Triangulum Galaxy's "supper massive black hole"?
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What is the Triangulum Galaxy's "supper massive black hole"?

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Offline Pseudoscience-is-malarkey (OP)

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What is the Triangulum Galaxy's "supper massive black hole"?
« on: 02/12/2022 20:26:05 »
Most astronomers are certain that the galaxy has no supermassive black hole at its center. This is due to its lack of a  pronounced bulge at its center and the fact that its deep core stars orbit its center slowly, unlike all the non-tiny galaxies we have observed, where they on average travel 1⁄60 the speed of light. So, how possible is it that the H 2 region that we now know exists in Triangulum's center is crowded so tightly with powerful stars that their gravities interact with each other as one giant gravitational force that's strong enough to attract and bind stars, but not strong enough to significantly influence their orbital speed.
« Last Edit: 18/12/2022 15:43:29 by Pseudoscience-is-malarkey »
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Offline evan_au

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Re: What is the Triangulum Galaxy's "supper massive black hole?
« Reply #1 on: 03/12/2022 21:09:06 »
Quote from: Wikipedia
Unlike the Milky Way and Andromeda galaxies, the Triangulum Galaxy does not appear to have a supermassive black hole at its center. This may be because the mass of a galaxy's central supermassive black hole correlates with the size of the galaxy's central bulge, and unlike the Milky Way and Andromeda, the Triangulum Galaxy is a pure disk galaxy with no bulge.
https://en.wikipedia.org/wiki/Triangulum_Galaxy#Discrete_features
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Offline Eternal Student

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Re: What is the Triangulum Galaxy's "supper massive black hole?
« Reply #2 on: 04/12/2022 03:46:19 »
Hi.
It's late and these are just some rough points that seem relevant.

Quote from: Pseudoscience-is-malarkey on 02/12/2022 20:26:05
So, how possible is it that the H 2 region that we now know exists in Triangulum's center is crowded tightly enough that their gravities (with the help of dark matter) act as one giant gravitational force that's strong enough to attract and bind stars, but not strong enough to significantly influence their orbital speed.

1.    As @evan_au  pointed out in the reference,  there is thought to be at least one black hole,  just not necessarily a super-massive one at the centre.

2.   Gravity is complicated.  Even Newtonian gravity is complicated.   We can find good solutions for what is called the two-body problem,  which literally just involves two bodies and gravity acting between them.  We can even make a bit of progress with a three-body problem,  however you get to four-bodies and the whole thing is just a "pig"  ("pig" just means difficult).   Most of the "solutions" or information about multi-body problems are just obtained from simulations and numerical approximation techniques and not from any analytical or exact solutions to the problem.
      Having a super-massive black hole at the centre of a galaxy is one easy way to have a stable structure that is a galaxy.   In a numerical approximation, the whole thing does behave a lot like a two body problem for everything close to the black hole.   You have the body you are considering (planet or star etc.) and the only other body of any importance is the black hole because nothing else has the mass to compete with that and so you can just neglect it.
    We don't know for certain that the Triangulum Galaxy doesn't have a SMBH at it's centre but let's assume it doesn't.  Then it just is another possible solution (a distribution of the diffuse matter like Hydrogen gas and the more dense bodies like planets in the system) for the multi-body problem that produces a stable structure like a galaxy.   There are going to be quite a few solutions.

3.       When analysing structures like galaxies and the orbit of certain things,  one of the approximations that can be used is just to draw a circle (well a 3-D spherical surface) around the point which the body seems to orbit out to a radius that is the radius of its orbit  (well more or less if it's elliptical or odd shaped)  and assume that there is a roughly uniform distribution of mass outside of that sphere.   We have results like the shell theorem which suggest the only thing(s) providing a net gravitational pull on that body and hence influencing the orbit of that body is the mass inside of that sphere.    I haven't seen the data for the Triangulum galaxy but I'm fairly confident that these are the sorts of techniques that would have been used to suggest that there wasn't much mass  (e.g. a SMBH) on the interior of some of the orbiting objects you mentioned   ("...its core stars orbit slowly...").   However, the core of the galaxy is not the only thing holding the galaxy together.  As you look at objects further out, that circle (or 3-D spherical surface - but for a fairly flat galaxy it's just a flat circle that you'll be interested in) which is the boundary of their orbit is much bigger.  This means there is more mass on the interior of that circle and hence much more that can be binding them.

4.    I'm not sure exactly what you meant with the sentence about binding and attracting stars in some H2 dense regions.   If you meant attracting H2 gas so as to form a new star.... well  stellar formation is accelerated by all sorts of processes and conditions.  Hydrogen gas might be getting driven into where these stars are forming rather than merely being attracted by the mass of whatever seed for a star was already there.   Also Hydrogen gas isn't all that heavy or "massive" is the correct term .  You don't need a lot of mass in your seed for a new star to attract some hydrogen gas, especially if the gas is already close to it.  The rate of star production is likely to be much more of an indication of the density or availability of H2 gas in that region rather than any indication that there is a lot of mass in that region.

Best Wishes.
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Offline Pseudoscience-is-malarkey (OP)

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Re: What is the Triangulum Galaxy's "supper massive black hole"?
« Reply #3 on: 17/12/2022 15:46:15 »
Quote from: Eternal Student on 04/12/2022 03:46:19
1.    As @evan_au  pointed out in the reference,  there is thought to be at least one black hole,  just not necessarily a super-massive one at the centre.

2.   Gravity is complicated.  Even Newtonian gravity is complicated.   We can find good solutions for what is called the two-body problem,  which literally just involves two bodies and gravity acting between them.  We can even make a bit of progress with a three-body problem,  however you get to four-bodies and the whole thing is just a "pig"  ("pig" just means difficult).   Most of the "solutions" or information about multi-body problems are just obtained from simulations and numerical approximation techniques and not from any analytical or exact solutions to the problem.
      Having a super-massive black hole at the centre of a galaxy is one easy way to have a stable structure that is a galaxy.   In a numerical approximation, the whole thing does behave a lot like a two body problem for everything close to the black hole.   You have the body you are considering (planet or star etc.) and the only other body of any importance is the black hole because nothing else has the mass to compete with that and so you can just neglect it.
    We don't know for certain that the Triangulum Galaxy doesn't have a SMBH at it's centre but let's assume it doesn't.  Then it just is another possible solution (a distribution of the diffuse matter like Hydrogen gas and the more dense bodies like planets in the system) for the multi-body problem that produces a stable structure like a galaxy.   There are going to be quite a few solutions.

3.       When analysing structures like galaxies and the orbit of certain things,  one of the approximations that can be used is just to draw a circle (well a 3-D spherical surface) around the point which the body seems to orbit out to a radius that is the radius of its orbit  (well more or less if it's elliptical or odd shaped)  and assume that there is a roughly uniform distribution of mass outside of that sphere.   We have results like the shell theorem which suggest the only thing(s) providing a net gravitational pull on that body and hence influencing the orbit of that body is the mass inside of that sphere.    I haven't seen the data for the Triangulum galaxy but I'm fairly confident that these are the sorts of techniques that would have been used to suggest that there wasn't much mass  (e.g. a SMBH) on the interior of some of the orbiting objects you mentioned   ("...its core stars orbit slowly...").   However, the core of the galaxy is not the only thing holding the galaxy together.  As you look at objects further out, that circle (or 3-D spherical surface - but for a fairly flat galaxy it's just a flat circle that you'll be interested in) which is the boundary of their orbit is much bigger.  This means there is more mass on the interior of that circle and hence much more that can be binding them.

4.    I'm not sure exactly what you meant with the sentence about binding and attracting stars in some H2 dense regions.   If you meant attracting H2 gas so as to form a new star.... well  stellar formation is accelerated by all sorts of processes and conditions.  Hydrogen gas might be getting driven into where these stars are forming rather than merely being attracted by the mass of whatever seed for a star was already there.   Also Hydrogen gas isn't all that heavy or "massive" is the correct term .  You don't need a lot of mass in your seed for a new star to attract some hydrogen gas, especially if the gas is already close to it.  The rate of star production is likely to be much more of an indication of the density or availability of H2 gas in that region rather than any indication that there is a lot of mass in that region.

Best Wishes.
Thanks for the reply, you're clearly very smart (I'm not being facetious). However, I take issue with your overuse of the spacebar. The attached file illustrates what I'm talking about. It's guys like you that are causing chaos on our forums... Get your act together.

* gg.png (904.84 kB, 2616x2588 - viewed 29 times.)
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Offline Eternal Student

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Re: What is the Triangulum Galaxy's "supper massive black hole"?
« Reply #4 on: 17/12/2022 21:25:20 »
Hi.

     Sorry.   I'm old enough to have used a typewriter.  It was recommended to put a double space after a full stop.  I'm too old to un-learn that now.   The rest of it is probably just error which age is also not going to improve.  Starting a new paragraph is also a good excuse for some serious indentation.
      There is a problem with the <TAB> button but that's a different story.

Best  Wishes.
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Offline evan_au

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Re: What is the Triangulum Galaxy's "supper massive black hole"?
« Reply #5 on: 17/12/2022 22:15:37 »
Quote from: Pseudoscience-is-malarkey
I take issue with your overuse of the spacebar
I think you have circled the location of the Dark Matter that holds this thread together...
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