All Questions
Tagged with cosmology dark-matter
265
questions
14
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3
answers
3k
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Is Dark Matter in Motion?
What is known about the motion of dark matter, especially in galaxies?
It seems as though a particular distribution of dark matter might be required to cause the very flat galactic rotation curves ...
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1
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0
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39
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About the spatial distribution of vacuum energy around strongly gravitating objects in the galaxy
We know that the distribution of vacuum energy is spatially uniform. But we also know that it couples to gravity.
Anything with energy, such as a beam of light is affected by the gravitational field ...
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1
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1
answer
167
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Could dark energy be explained via the use of a "gravitational charge"?
Could gravity be explained as the existence of a "gravitational charge", acting similarly to an electromagnetic charge but where like charges attract and opposite charges repel? A graviton ...
1
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0
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37
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Axions approaching thermal distribution
I am reading Sikivie's paper on Axion Cosmology. I have the equation:
$$\frac{\mathrm{d}}{\mathrm{dt}}[R^3(n_a^{th}-n_a^{eq})] = -\Gamma R^3(n_a^{th}-n_a^{eq}) \tag{1}$$
where $R(t)$ is the ...
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Could quantum vacuum polarization increase GR frame dragging beyond the predicted values and therefore replace DM explanation of galactic rotation? [duplicate]
image source credits:David Butler
This anomalous speed rotation distribution of galaxies is today mainly contributed to Dark Matter.
However, since a definitive experimental measurement and ...
- 4,170
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1
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101
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Dark Matter/Energy & Space-Time [closed]
After searching for quite a while for a minimalist approach to explaining Dark Matter as well as Dark Energy, unfortunately without much good, I decided I may as well help fill the explored paths, or ...
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3
votes
2
answers
133
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Is there an acknowledged unsolved problem in some cosmological theories with respect to "dark" matter and general relativity?
Some mainstream cosmological hypotheses hold both that:
general relativity is correct and universal; and
a form of "dark" matter exists that is, in somewhat of a misnomer, "non-...
- 153
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1
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Could Dark Matter imply the existence of Dark energy? [closed]
This is admittedly a simple example, but it seems to check out. Consider the standard metric for the Schwarzschild solution in coordinates $(t, r,\theta,\phi)$:
$$ g_{oo} = U, \ g_{11} = V, \ g_{22} = ...
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0
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35
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What is the dark energy & dark matter? [duplicate]
Can anyone explain to me simply what is the dark energy or what is the dark matter. I have been trying to understand it deeply. but I somehow failed.
15
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4
answers
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If dark matter can't lose kinetic energy, then why is it not traveling at relativistic speeds?
I have read this question:
The only way you can do this is to remove kinetic energy from the system.
With normal matter this is done through electromagnetic interactions, which turn the kinetic ...
- 29k
3
votes
1
answer
337
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If dark matter can't clump together, then where was it when the observable universe was much smaller at the beginning of the universe?
I have read this question:
To zeroth order, dark matter can only 'clump' as much as its initial energy (obtained soon after the big-bang) allows. One example of such a 'clump' is a 'Dark Matter Halo' ...
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2
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1
answer
207
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Can Integrating out Dark Matter give Modified Gravity?
I'm sure I misunderstood something obvious, but reading this question, I wondered what philosophically is the difference between modified gravity (like TeVeS, f(R), etc.) and dark matter, if/since we ...
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1
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104
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Given current densities of dark energy, dark matter and normal matter in universe currently, calculate ratio of density of dark matter at CMB to now? [closed]
I stumbled upon this question while preparing for the astronomy Olympiad.
It is question #17 in this pdf.
Given that dark energy is vacuum energy, and that the densities of dark energy, dark matter ...
1
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1
answer
75
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How can we calculate formula for effective coupling constant in spin independent direct detection of dark matter?
At tree level, the spin independent
(SI) direct-detection cross section includes effective coupling constant. How to calculate effective coupling constant?
There is always a mandelstram variable in it....
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4
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2
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298
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Scalar field displacement from the minimum of the potential gives rise to particles/dark matter, why?
In This paper (Kobayashi et al -- Lyman-alpha Constraints on Ultralight Scalar Dark Matter: Implications for the Early and Late Universe) it says, at the beginning of Section 3.1:
A light scalar ...
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