All Questions
73
questions
2
votes
2
answers
110
views
Will a neutrino gas always stay at the same temperature?
Does the neutrino gas pervading the universe always have the same temperature? Does it still have the temperature as the neutrino gas that emerged from the big bang? Neutrinos don't interact, so how ...
1
vote
0
answers
25
views
How do you relate the number densities of neutrinos and photons soon after the positron–electron annihilation?
I found this equation:
$n_\nu = \frac{3}{4} \frac{g_\nu T_\nu^3}{g_\gamma T_\gamma^3} n_\gamma$
Where does it come from?
- 84
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
0
votes
0
answers
47
views
What is the reheating temperature of neutrinos during the BBN?
I want to integrate a differential distribution function of sterile neutrinos and the boundaries are the decoupling and the reheating temperature of neutrinos, but I don't know what is an acceptable ...
- 753
0
votes
1
answer
242
views
Could cosmological cold dark matter be a neutrino condensate?
What is wrong with the following? (Note that the question is not about galactic dark matter, but about cosmological dark matter.)
Neutrinos are dark matter.
A neutrino condensate would be cold. (...
user85598
11
votes
2
answers
448
views
Cold neutrinos - how are they distributed?
Cold or slow neutrinos have non-relativistic velocities and hence very low energies. That makes them very difficult to detect. Answers to Where are all the slow neutrinos? make it clear that they are ...
- 7,438
3
votes
2
answers
232
views
Are ultra-cold neutrinos an option for cold dark matter? [duplicate]
Nobody hass seen cold dark matter. Are ultra-cold (non-relativistic) neutrinos, below 1 fK (femtokelvin), an option for dark matter?
This is a question about normal neutrinos - electron neutrinos and ...
user85598
1
vote
0
answers
57
views
$N$-body simulation with varying neutrino mass
I am trying to find a picture of the $N$-body simulations that shows the LSS. Particularly I am looking for different neutrino masses without the CDM. For instance pictures likes this
But with more ...
1
vote
0
answers
88
views
Deriving the free streaming distance for HDM particles
I am trying to derive the free-streaming length for the HDM particles but I couldnt follow the arguments given by the article https://arxiv.org/pdf/astro-ph/0201405v1.pdf after equation 83.
Thanks
- 3,122
10
votes
1
answer
442
views
Are neutrinos and sterile neutrinos both dark matter candidates?
Are both neutrinos and sterile neutrinos candidates for dark matter?
In particular, why would "standard" neutrinos be a candidate for dark matter, since they interact with matter?
Why would ...
0
votes
1
answer
51
views
How are neutrinos massless? Could they or at least some of their forms be a potential candidate for Dark matter? [duplicate]
I am particularly new to this subject. Can neutrino physics be understood by a 10th grade?
- 1
2
votes
0
answers
48
views
Should the CNB be comoving with the CMB? [duplicate]
The neutrino decoupling and the photon decoupling happened after the big bang, though at different times. The CMB is very detectable, and although there is no universal reference frame, the CMB is ...
- 29k
-1
votes
2
answers
92
views
Cosmic neutrino background ($C_{\nu}B$) [duplicate]
Usually when you calculate the total density of radiation of the universe you use the formula:
$$\rho_{R}=\rho_{\gamma}+\rho_{\nu}$$
Where $\rho_{\gamma}$ is the density of photons and $\rho_{\nu}$ ...
- 429
1
vote
1
answer
262
views
Book suggestion about Neutrino effect on Cosmic Structure
I am trying to find some nice explanatory books about neutrino effects on the cosmic structure. I did not take GR so I prefer sources that contain not much GR.
I prefer lecture note series or books ...
1
vote
1
answer
46
views
Calculating the maximum total neutrino mass by using cosmological bound
In an article its written,
$$\Omega_{\nu} = \frac{\rho_{\nu}}{\rho_{crit}}=\frac{\sum m_{i,\nu}n_{i,\nu}}{\rho_{crit}} = \frac{\sum m_{\nu}}{93.14h^2eV}$$
Now I am trying to derive this for myself ...
- 3,122