Questions tagged [redshift]
Questions related to the phenomenon whereby electromagnetic radiation (such as visible light) generated by an object moving away from an observer will have increase in wavelength (i.e. shifted toward the red end of the spectrum) once it reaches the observer.
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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 ...
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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 ...
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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 ...
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Why would some sources in a cross-matched DESI/SDSS catalog have different spectroscopic redshifts?
I've crossmatched quasars from DESI DR9 and from SDSS DR16. When I plot the spectroscopic redshift from each of the individual catalogs for each source, I get:
Naively, I'd expect the $z_{spec}$ to ...
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Using prospector for jwst data
I am working with JWST data. I want to estimate the redshift of the sources I have identified with SEXtractor with the help of prospector. Can somebody guide me in this?
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How do we work out the light travel time on a cosmic scale?
I just read this article in the AUSTRALIAN SKY & TELESCOPE magazine, Nov/Dec 2022 Issue 140, on P16, KEEP YOUR DISTANCE: How far away are the objects we see in the universe? And on P23:
"And ...
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Does a cosmological redshift occur within our local group, of galaxies?
I know that it is not supposed to be expanding but space is space and it is expanding everywhere else outside it so why not inside it too, and gravity just holds everything back.
I suppose if it is, ...
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Why are distant type Ia supernovae dimmer than expected?
Why are the (extremely) distant type Ia supernovae dimmer than expected?
Relative to what? Their cosmological red shift? Well, what else.
Please don't just say "Because the expansion is ...
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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 ...
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Why does a Decision Tree produce lines in photometric redshift predictions?
In this paper, the authors compare the speed and accuracy of various machine learning algorithms to produce photometric redshift estimates:
Why does the DT regressor put the estimates into bands ...
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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-...
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JWST Early Black Holes: Gas Collapsed To Metallic Hydrogen Core?
I was reading an article about early black holes found by JWST at Redshift 9. And saw that there was wonder at how large amounts of gas could collapse into a black hole as a theory.
So my question is ...
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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 ...
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The "k-effect"?
I'm reading some older materials which refer to something called the "k-effect". This was described as "hot stars in the Sun’s neighborhood are moving away from us in all directions, ...
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How does doppler shift work for distant stars [duplicate]
I dont understand how you can look at the light from a star and say that it has been doppler shifted. For example a star emits a photon in the wavelength of 500nm and by the time it reaches earth it ...
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