All Questions
16
questions
1
vote
1
answer
183
views
Does NFW profile work for any galaxy?
We use Navarro–Frenk–White (NFW) to calculate Dark Matter (DM) density. Can we use it for DM halo in any galaxy or is it used only for Milky Way (MW)?
- 11
3
votes
1
answer
119
views
Could a fourth family of quarks and leptons account for dark matter?
In the early universe, could a family of quarks and leptons have formed an electrically neutral particle that is dark matter?
user361671
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
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
1
answer
192
views
Dark matter in the time window between freeze-out and kinetic decoupling
Background
After the freeze-out, when all annihilations have stopped, the abundance ($Y=\frac{n}{s}$) of thermal dark matter species no longer changes with time. However, it is still kept in kinetic ...
- 26.8k
11
votes
2
answers
547
views
If neutrinos are disfavoured as DM candidates why aren't axions?
Numerical simulations of observed large-scale structure formation work best with Cold Dark Matter (CDM; see the answer here). Neutrinos are candidates for Hot Dark Matter (HDM), and hence they cannot ...
- 26.8k
3
votes
1
answer
1k
views
Why is the dark matter freeze-out temperature $T\sim \frac{m}{20}$ so generic?
For a dark matter of mass $m$, the typical freeze-out temperature is $T$ is usually assumed to be between $\frac{m}{20}-\frac{m}{25}$. But the freeze-out temperature depends upon the annihilation ...
- 26.8k
0
votes
1
answer
186
views
Why can't the Higgs vacuum energy clump to galaxies and act as dark matter (instead of dark energy)? [closed]
The Higgs field has a nonzero vacuum expectation value which contributes to the energy density of the Universe. Energies contribute to the curvature of spacetime and affected by gravitational ...
- 26.8k
4
votes
1
answer
239
views
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
2
votes
2
answers
489
views
Why do we think that the dark sector is simpler?
Matter makes up roughly $5\%$ of the Universe while dark matter makes up roughly $25\%$. For matter and radiation, we have a complicated Standard model with many generations of fermions and various ...
- 26.8k
4
votes
1
answer
185
views
About the consequences of $\mathbb{Z}_2$ invariance in dark matter models
This well-cited paper talks about is 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
5
votes
2
answers
190
views
Why did dark matter interact with the Standard model particles in the early Universe but not now?
In the thermal dark matter (DM) scenario, it is the interaction of the DM particles with the Standard Model (SM) particles that kept the DM particles in kinetic equilibrium with the thermal plasma.
...
- 26.8k
6
votes
1
answer
527
views
Why is the Standard model Higgs not a candidate of dark matter (in particular, a WIMP)?
Please consider me as a naive self-learner in this field.
The Standard Model (SM) Higgs boson is electrically neutral and has a mass of around $125$ GeV (which lies in the WIMP window i.e., between ...
- 26.8k
4
votes
2
answers
183
views
What are the steps to identify a dark matter candidate?
By looking at the Lagrangian of a simple particle physics model, how do people identify the dark matter (DM) candidates, if any?
One of the criteria is to check whether the electric charge of the ...
- 26.8k
3
votes
1
answer
249
views
How did dark matter become a relic?
Why did the decay rate of the dark matter particles fall when the temperature of the Universe $T_U$ dropped below dark matter mass $M_{DM}$?
In particular, why can it not decay into lighter particles ...
- 26.8k