All Questions
10
questions
4
votes
1
answer
481
views
Cosmic neutrino background temperature
In my cosmology lecture course, we derived the temperature of the cosmic neutrino background as
\begin{equation}
T_{\nu} = \left(\frac{4}{11}\right) ^ {1/3} T_{\gamma} \,.
\end{equation}
Since the ...
- 109
3
votes
4
answers
424
views
How can the Cosmic Neutrino Background (CνB) have a temperature? How can any neutrino have a 'temperature'?
The word temperature usually refers to the average velocity of massive particles, correct?
And the Cosmic Microwave Background (CMB) has a 'temperature' based on the temperature of a 'black body' that ...
- 4,509
3
votes
1
answer
75
views
How did neutrinos eliminated from dark matter? [duplicate]
I am reading "Dark Matter and Dark Energy" by Brian Clegg.
In Chapter 3 it's discussing about cosmic microwave background radiation and the elliptical shape
of early universe obtained from ...
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
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
3
votes
1
answer
107
views
Is there a bound on the number of sterile neutrinos from cosmological observations?
The right-handed sterile neutrinos $\nu_{R}$ are electroweak singlets. They do not contribute to the electroweak anomaly, and therefore, their number is not fixed by the requirement of the anomaly ...
- 26.8k
4
votes
1
answer
506
views
Cosmic gravitational background and its temperature [duplicate]
There is a cosmic microwave background, according to the Big Bang theory. There is also a cosmic neutrino background, at 1.945 K, yet to be discovered, according to the Big Bang theory. My question is:...
- 6,611
8
votes
2
answers
256
views
Reference frame for the Cosmic Neutrino Background
It is well known that there exists a reference frame where the total momentum of the Cosmic Microwave Background is zero (a basic fact of special relativity applied to a collection of massless ...
- 5,684
0
votes
0
answers
51
views
I need Resources on CMB Neutrinos
I am doing a research paper for upper level undergrad class on CMB neutrinos (C$\nu$B). I need papers that explain CMB Neutrinos from the ground up like the main theory behind the CMB Neutrinos and ...
5
votes
1
answer
1k
views
How Does Cosmology Constrain the Number of Neutrino Species?
I know that based upon theories of structure formation cosmologists can constrain the sum of the masses of neutrinos - if neutrinos were too light or too heavy it would simply change the power ...
- 679