All Questions
Tagged with cosmology dark-matter
29
questions with no upvoted or accepted answers
4
votes
1
answer
110
views
Is the amount of dark matter per galaxy the same as you look back through time (further away from earth)?
In the hope that it may inform us about the development/evolution (if any) of dark matter over time, are there any differences (eg. in structure or concentration) in the dark matter at large radial ...
- 351
4
votes
1
answer
239
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How are the dark matter (DM) thermalization rates derived in singlet DM model?
This well-cited paper talks about a minimal renormalizable extension to the Standard Model (SM) to incorporate particle dark matter (DM) into it by adding a real scalar field $S$ which (unlike the ...
- 26.8k
3
votes
0
answers
49
views
What properties of dark matter can we derive from each of the available methods for probing the physics of dark matter?
This is probably a long shot but it's worth trying. My question is the following:
What properties of dark matter can we derive from each of the available methods for probing the physics of dark matter?...
- 373
3
votes
0
answers
75
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Active-sterile mixing for KeVins
People sometimes talk about KeV mass sterile neutrinos as a warm dark matter candidate. I think they call them KeVins (horrible name btw). Now, In order for it to be a good dark matter candidate it ...
- 1,043
2
votes
0
answers
90
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Gravitational halos made of neutrinos...?
I have been recently interested in how halos made of standard model particles could be formed and behave.
After asking some questions in this site, I was told about how neutrinos could form such halos....
- 2,462
2
votes
1
answer
70
views
If dark matter is axion particles, how did such light particles slow down?
One candidate for dark matter is axions and there is tentative experimental evidence for their existence.
Axions are very light, most models weigh them in at tiny fractions of an eV. It seems like ...
- 6,531
2
votes
0
answers
42
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Did galaxies spin differently 4, 5, 6 billion years ago?
Today I read that the Matter-dominated era ended 4 billion years ago, and now we're in the Dark Energy dominated era.
Obviously, light from galaxies far enough away would be from earlier in the ...
- 121
2
votes
0
answers
168
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Dark matter/dark energy in Einstein's equation as manifestations of entropy production
It is well known that pressure adds a contribution to the gravity sources in Einstein's equation. That contribution is unknown in Newton's theory. What about entropy itself, or more precisely the ...
- 7,592
2
votes
0
answers
140
views
How does dark matter distribution help to identify it's composition
A question regarding this recently released data,
and the paper https://arxiv.org/abs/1708.01538 that details it's distribution:
Abstract:
We use 26 million galaxies from the Dark Energy Survey (...
user163104
2
votes
0
answers
382
views
Why would be axions be a candidate for warm/cold dark matter?
Axions are the current main favoured candidate for the identity of dark matter. While their masses are sub-$\mathrm{eV}$, why is it that they would be cold or possibly warm dark matter candidates ...
- 1,788
1
vote
0
answers
84
views
The 'core-cusp' problem for dark matter halos in larger galaxies
TLDR: Do observations of larger galaxies favour 'cuspy' dark matter halo distributions, as predicted by N-body simulations?
I've been trying to understand the 'core-cusp' problem for dark matter halos ...
- 11
1
vote
0
answers
39
views
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 ...
- 26.8k
1
vote
0
answers
37
views
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 ...
- 1,222
1
vote
0
answers
45
views
Possibility of reaching equilibrium starting with a nonequilibrium initial condition in the early radiation-domination
Update after @knzhou's comment
If in a theory, the coupling of the dark matter (DM) field to the Standard Model (SM) fields is small enough, the rate of interaction of the DM particles in the ...
- 26.8k
1
vote
0
answers
28
views
Hydrogen-One (HI) Image and R-band
In the paper below, on page 3, it says "In the lack of HI image, we use the r-band b/a ratio to correct for the inclination". Am I correct in thinking that what this means is that if we ...
- 153