All Questions
54
questions
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Answer this or don't downvote
Otherwise you'll be showing your complete ignorance in the matter and contempt for the truth.
If the scale factor as a function of time represents or is equal to the average distance between the ...
5
votes
1
answer
236
views
How can you calculate the distance to an object knowing its cosmological redshift? (without Hubbles law)
Given some redshift z, how do we find the distance using the cosmological red shift formula (and presumably the Friedmann equations)? a = 1/(1+z), and we can assume that omega_0 = 1. I know a ...
- 51
-1
votes
1
answer
132
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CMB redshift used to determine the difference in aging between the two inertial observers
If CMB redshift tells us our cosmological time dilation and we have two inertial observers in relative motion, who measure slightly different CMB redshift at the direction of their motion relative to ...
-2
votes
1
answer
213
views
Shouldn't the Friedmann equation take into account the massive extra distance traveled during the time for gravity to travel across the universe? [closed]
I’ve got a question that has been bothering me for the past few years that of the few sources that are only somewhat related to this, none of them say anything about this should be wrong so I can’t ...
- 21
0
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0
answers
35
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Is the difference of redshift parameter z able to prove expansion is accelerating in flat FLRW universe model?
Sorry for my bad english, this is not my mother tongue.
Recently, I've encountered a problem in cosmology class that is about FLRW universe.
Assuming that the universe we inhabit is composed of non-...
- 1
1
vote
1
answer
113
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Finding an expression for the rate of change of Comoving volume with respect to redshift
I am trying to find the expression for the rate of change of comoving volume with respect to redshift, that is $\frac{\mathrm{d}V_c}{\mathrm{d}z}$. In this paper (Hogg, David W.), the comoving volume ...
- 75
8
votes
1
answer
2k
views
Is Webb or any near-future telescopes like ELT capable of observing redshift changes to confirm General Relativity?
The (Davis and Lineweaver (2003)) "Expanding Confusion" paper states that "the expected change in redshift due to cosmological acceleration or deceleration is only ∆z ∼ 10^(−8) over 100 ...
- 175
2
votes
0
answers
98
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Empirical Constraints on the Time Evolution of Cosmological Redshifts
The standard model of Cosmology predicts that the redshift of a single source at fixed comoving distance varies with observation time according to
$$ \dot z = \left( 1+z - \frac{H(z)}{H_0} \right) H_0....
- 121
2
votes
1
answer
277
views
3d distance between the Galaxies inside the galaxy cluster
I am currently working on the dynamics of the galaxy cluster, so i am trying to get the distance between the galaxies inside the galaxy cluster from its centre. As a input i have RA , DEC and Z (...
- 41
3
votes
1
answer
333
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Redshift distance proportionality at high Z and need for "mighty mouse" galaxies?
Allegedly supported by some evidence from the new James Webb space telescope physicist Eric Lerner has written an article that have garnered some attention. He writes that:
"Put another way, the ...
- 457
2
votes
0
answers
194
views
Plotting galaxies in 3-D
Suppose I have a catalogue of galaxies in a .dat file with each row representing information about a galaxy: right ascension of the galaxy, declination of the ...
- 71
2
votes
1
answer
693
views
Why is the CMB's redshift so high?
It is pretty well-established that the CMB was originally emitted around 380,000 years after the Big Bang, at a redshift of ~1100.
The most distant known object is HD1, the light from which was ...
- 284
1
vote
0
answers
62
views
Angle to the line of sight
I don't understand this angle used in galaxy clustering. There is the line of sight and this angle to the line of sight which is not clear to me. Here is a transcript of a description from 1705.05442:
...
- 11
1
vote
0
answers
124
views
How are CMB frame redshifts of galaxies corrected for coherent flows?
Say, if I downloaded the CMB frame redshifts of some galaxies from NED database, then what is the procedure to correct it for coherent flows?
I'm using the SNooPy(snpy) Python package to analyze some ...
1
vote
0
answers
14
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Stellar connectivity for different cosmological redshifts
I'm creating models of stellar connectivity, for a range of cosmological redshifts (z=9, z=7, z=5, z=3, z=1, z=0, z=0.5).
For that I'm doing the following steps:
Sampling simulation sub-halos for ...
- 173