Mass of a galaxy without dark matter and with dark matter

In summary, without dark matter, a galaxy would not exist. However, the mass of a galaxy does not change much when dark matter is included.
  • #1
Quarlep
257
4
I am curious about mass of a galaxy without dark matter and with dark matter.I searched but I couldn't found.I ll be happy If you help me.

Thanks
 
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  • #2
Well, without dark matter there most likely would not BE any galaxy. although DM does not "clump" the way normal matter does, it has somehow accumulated into cosmologically massive blobs that then attract regular matter through gravitational attraction and the regular matter clumps into stars and planets and dust and the whole mess is a galaxy.

So asking what a galaxy would be like without the dark matter is a bit like asking how well someone could sing if they had no vocal chords.
 
  • #3
Without dark matter I mean without dark matter mass my fault I forget mass
 
  • #4
Quarlep said:
Without dark matter I mean without dark matter mass my fault I forget mass
Yes, that is exactly what I was talking about.
 
  • #5
Quarlep said:
Without dark matter I mean without dark matter mass my fault I forget mass
How does that change the question?

For an existing galaxy, you can ask how much visible and how much invisible mass there are. The answer depends on the galaxy and the radius you consider (galaxies do not have sharp edges, especially in the dark matter distribution), but there are many galaxies where numbers are available online.
 
  • #6
I think the ratio of dark matter to matter is about the same in a typical galaxy (DM halo included) as the overall ratio of 85:15 but I could very well be wrong.
 
  • #7
wabbit said:
I think the ratio of dark matter to matter is about the same in a typical galaxy (DM halo included) as the overall ratio of 85:15 but I could very well be wrong.
The rabbit ? WRONG ? Not very likely :smile:
 
  • #8
Don't joke about the poor rabbit :) he's still recovering from almost loosing his legs in a black hole:smile:
 
  • #9
Is that right isn't it 85/15
 
  • #10
wabbit said:
I think the ratio of dark matter to matter is about the same in a typical galaxy

There exist both DM-rich and DM-poor galaxies.
 
  • #11
Quarlep said:
Is that right isn't it 85/15
do you not understand that 85:15 IS 85/15 or are you making a joke?
 
  • #12
wabbit said:
Don't joke about the poor rabbit :) he's still recovering from almost loosing his legs in a black hole:smile:
I TOLD you to stay away from those things !
 
  • #13
Yes mom, I won't do it again, promise:)
 
  • #14
Vanadium 50 said:
There exist both DM-rich and DM-poor galaxies.
I was wondering about that, or something related rather - in galaxy collisions the matter tends to coalesce into a single galaxy after a while due I believe to some kind of friction - but with high enough collision velocity it seems that (some part of) the dark matter halos could just move through each other and continue on their way. If that does happen, not only would we be left with a DM poor merged galaxy, but also with stray haloes of dark matter zooming away without much matter left in them . Is that something that happens and if so do we see such stray halos (through lensing or other means)?
 
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  • #15
Well, there are objects like the bullet cluster where the distribution of dark matter differs significantly from the distribution of gas.
Stars also don't have much friction, so a complete separation of visible and dark matter would be odd.
 
  • #16
Thanks, I thought "some kind of friction" arising from matter-matter interaction (gas clouds maybe?) played a role in the merger process - but you re saying it's minor and essentially gravitational effects alone explain the process, did I get that right?

And yes I was thinking of the bullet cluster - though I don't recall seeing mention of stray halos escaping in that case, so I was freely extrapolating - perhaps a little too far : )
 
  • #17
wabbit said:
Thanks, I thought "some kind of friction" arising from matter-matter interaction (gas clouds maybe?) played a role in the merger process - but you re saying it's minor and essentially gravitational effects alone explain the process, did I get that right?
Actually, I think the dust interactions DO contribute an effect, it's just that stars/planets are so far apart that THEY don't hit each other.
 
  • #18
phinds said:
do you not understand that 85:15 IS 85/15 or are you making a joke?

Yeah I understand it like that
Its not 85/15 then what it is.
 
  • #19
I was watching House and there House said dark matter makes galaxies 6 times bigger mass.And I am curious about is that same for every galaxy ? Example a galaxy mass is m without dark matter.But with dark matter 6m.Is that true for all galaxies ? (85/15 near to 6 so I made a connection)
 
  • #20
Quarlep said:
I was watching House and there House said dark matter makes galaxies 6 times bigger mass.And I am curious about is that same for every galaxy ? Example a galaxy mass is m without dark matter.But with dark matter 6m.Is that true for all galaxies ? (85/15 near to 6 so I made a connection)
Which part of post #10 did you not understand?
 
  • #21
Vanadium 50 said:
There exist both DM-rich and DM-poor galaxies.

So DM does not depend mass of galaxy.But this sound like stupid I guess.In quote I guess he means mass depend DM which less mass galaxies have Poor DM and heavier galaxies have Rich Dm
 
  • #22
The whole DM issue is confusing. Some galaxies appear to be rich in it, and others largely lacking. That suggests we may be missing an important clue.
 
  • #23
I understand.Do you have any internet resources for that.This extra mass idea or DM rich DM poor stuff
 
  • #25
Quarlep said:
But this sound like stupid I guess

If you don't like what I said, provide a counterexample or counterargument, or at least ask a question. Don't just call it stupid. It's not just unhelpful. It's rude.

If you bothered to type "dark matter rich galaxies" in Google, you would have gotten 70,600 hits. If I were you, I'd do a bit more research before telling other people that they are wrong.
 
  • #26
I didn't read his post as calling you stupid , but saying the way he initially understood it sounded stupid. OP is clearly not using his first language here.
 
  • #27
Vanadium 50 said:
If you don't like what I said, provide a counterexample or counterargument, or at least ask a question. Don't just call it stupid. It's not just unhelpful. It's rude.

If you bothered to type "dark matter rich galaxies" in Google, you would have gotten 70,600 hits. If I were you, I'd do a bit more research before telling other people that they are wrong.

I didnt tell you stupid.If you understand like that I am very very sorry.

"I didn't read his post as calling you stupid , but saying the way he initially understood it sounded stupid. OP is clearly not using his first language here"

Wabbit is right.I tried to say this idea sounds like stupid And he is right again my first language is not english.
 
  • #28
Chronos said:
Examples include: http://arxiv.org/abs/astro-ph/0308518, A Dearth of Dark Matter in Ordinary Elliptical Galaxies; and http://arxiv.org/abs/1410.8141, Forty-Seven Milky Way-Sized, Extremely Diffuse Galaxies in the Coma Cluster.
.
I read them and I found them interesting.But I want to ask something , this cases are extraordinary but this cannot be the hole story.I want to ask you in generally how DM affects mass of galaxy.Theres 100 billion galaxies generally what can we say ?
 
  • #29
The mass of the galaxy is a bit more than the mass of its dark matter. Where "a bit" depends on which galaxy you look at, but it is somewhere around 20% more on average.
Most of the mass in the universe is dark.
 
  • #30
Lets suppose we have a galaxy mass 5m then dark matter mass will be 4m then total mass will be 9m so total mass is 2 times bigger then the galaxy mass in the average isn't it ?
 
  • #31
"Galaxy mass" includes the dark part.

Your galaxy would (on average) have 4m dark matter and 1m visible matter (more precise: baryonic matter), for a total of 5m. 80% of the 5m are dark.
 
  • #32
Ok thanks
 
  • #33
Checked post # 10, but wonder, has there been a galaxy the Hubble has locked on, that does not have dark matter to some degree? My questions: what is DM and what is its reason for its being, if in fact it exists?
 
  • #35
Quarlep said:
I am curious about mass of a galaxy without dark matter and with dark matter.I searched but I couldn't found.I ll be happy If you help me.

Thanks
There are many Theories which define the start of universe differently. 1 among them say that universe begin with the break down of black holes and would end when entire mass of universe is pulled back by black hole. Yet the reality is undiscovered :)
 
<h2>1. What is the difference between the mass of a galaxy with and without dark matter?</h2><p>The mass of a galaxy with dark matter is significantly higher than the mass of a galaxy without dark matter. Dark matter is estimated to make up about 85% of the total mass of a galaxy, while the remaining 15% is made up of visible matter such as stars, gas, and dust.</p><h2>2. How do scientists determine the mass of a galaxy?</h2><p>Scientists use a variety of methods to determine the mass of a galaxy, including measuring the orbital speeds of stars and gas, analyzing the gravitational lensing effect, and studying the rotation curves of galaxies.</p><h2>3. Can dark matter be directly observed?</h2><p>No, dark matter cannot be directly observed because it does not interact with light. However, its presence can be inferred through its gravitational effects on visible matter.</p><h2>4. Why is dark matter important in understanding the structure of galaxies?</h2><p>Dark matter plays a crucial role in the formation and evolution of galaxies. Its gravitational pull allows galaxies to form and hold their shape, and it also affects the distribution of visible matter within a galaxy.</p><h2>5. Are there any theories that can explain the nature of dark matter?</h2><p>There are several theories that attempt to explain the nature of dark matter, including the WIMP (Weakly Interacting Massive Particles) theory and the MACHO (Massive Compact Halo Objects) theory. However, the exact nature of dark matter is still a mystery and continues to be a subject of ongoing research and debate in the scientific community.</p>

1. What is the difference between the mass of a galaxy with and without dark matter?

The mass of a galaxy with dark matter is significantly higher than the mass of a galaxy without dark matter. Dark matter is estimated to make up about 85% of the total mass of a galaxy, while the remaining 15% is made up of visible matter such as stars, gas, and dust.

2. How do scientists determine the mass of a galaxy?

Scientists use a variety of methods to determine the mass of a galaxy, including measuring the orbital speeds of stars and gas, analyzing the gravitational lensing effect, and studying the rotation curves of galaxies.

3. Can dark matter be directly observed?

No, dark matter cannot be directly observed because it does not interact with light. However, its presence can be inferred through its gravitational effects on visible matter.

4. Why is dark matter important in understanding the structure of galaxies?

Dark matter plays a crucial role in the formation and evolution of galaxies. Its gravitational pull allows galaxies to form and hold their shape, and it also affects the distribution of visible matter within a galaxy.

5. Are there any theories that can explain the nature of dark matter?

There are several theories that attempt to explain the nature of dark matter, including the WIMP (Weakly Interacting Massive Particles) theory and the MACHO (Massive Compact Halo Objects) theory. However, the exact nature of dark matter is still a mystery and continues to be a subject of ongoing research and debate in the scientific community.

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