Dark Matter and Gravity

[foodchain]

Does dark matter or dark energy, or dark stuff in general actually interact with gravity? I know modern interpretations of it hold that gravity is the only way currently to determine the existence of such stuff, and that such stuff does not interact with any other fundamental force, but in all reality is there actual science to prove that dark stuff actually does indeed physically interact with gravity, or could such a correlation be explained away by other means?

[steevey]

Dark matter interacts with gravity, but not the electromagnetic force which is why it would have to be super-dense (since gravity is the only thing holding it together).

 

Dark energy is it's own thing which works against the effects of gravity.

 

Different "dark" things aren't the same and don't have the same properties.

[imatfaal]

Is dark matter necessarily super dense? I didn't think we even had that amount of info - all we have is a rough idea of mass per cubic volume, and that could be a few clumps of very dense or a sea of small and light. there is definitely a huge amount of it - but then it is in a very large volume .

 

Gravity works on the product of masses not on the density; the density could affect how close the centres of mass could be, but on cosmological scales in this matter this wouldn't be important.

[D H]

Dark matter interacts with gravity, but not the electromagnetic force which is why it would have to be super-dense (since gravity is the only thing holding it together).

 

It's the other way around (that is, diffuse rather than "super-dense"). If dark matter clumped the way "normal" matter does it would only serve to exacerbate the galaxy rotation problem. Dark matter comes to the rescue only if it forms a diffuse cloud around galaxies, aka the dark matter halo.

 

 

 

[steevey]

It's the other way around (that is, diffuse rather than "super-dense"). If dark matter clumped the way "normal" matter does it would only serve to exacerbate the galaxy rotation problem. Dark matter comes to the rescue only if it forms a diffuse cloud around galaxies, aka the dark matter halo.

 

 

 

 

That's one theory, but I've heard of dark matter being really dense and simply existing in regions around the galaxy holding it together.

 

Is dark matter necessarily super dense? I didn't think we even had that amount of info - all we have is a rough idea of mass per cubic volume, and that could be a few clumps of very dense or a sea of small and light. there is definitely a huge amount of it - but then it is in a very large volume .

 

Gravity works on the product of masses not on the density; the density could affect how close the centres of mass could be, but on cosmological scales in this matter this wouldn't be important.

 

But I'm saying if there's no positive and negative charges holding it together, then in order for it to exist in any measurable amount, it would probably be compacted since gravity would be too weak by itself to hold the material together unless its on a massive scale. So if there's a large amount of it like the size of a white dwarf, it would probably be very dense.

Edited February 8, 2011 by steevey

[alpha2cen]

It's the other way around (that is, diffuse rather than "super-dense"). If dark matter clumped the way "normal" matter does it would only serve to exacerbate the galaxy rotation problem. Dark matter comes to the rescue only if it forms a diffuse cloud around galaxies, aka the dark matter halo.

 

 

 

 

The Dark Matter halo concept comes from the phenomena that the velocity distribution of the star movement according to radial direction in the Galaxy is different from the computed results based on Newtonian fluid assuming.

But I have not seen any literature about the result that Dark Matter halo simulation is well fitted with the observed data.

Are there any good literature about this simulation?

In order to do this simulation, we have to assume the Dark Matter property value.

Edited February 8, 2011 by alpha2cen