- #1
ChrisVer
Gold Member
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I have a problem with some question I had to answer for the Surface Brightness [itex]\Sigma \propto \frac{Flux}{Angular~area}= \frac{F}{\Omega}[/itex].
I was able to show that [itex] \Sigma \propto (1+z)^{-4} [/itex]
Then the question asks whether knowing its value for known candles or yardsticks, is a good way to determine the cosmological parameters...
I think that determining it will allow us to determine the redshift [itex]z[/itex] and thus the scale factor [itex]a[/itex] and its evolution. So we can know how [itex]a[/itex] evolves and thus obtain the cosmological parameters from the Friedmann equations. Is that wrong?
However, somewhere I read that the dependence of [itex](1+z)^{-4}[/itex] is independent on the cosmological model ,something that made me think I was wrong... :(
Any idea?
I was able to show that [itex] \Sigma \propto (1+z)^{-4} [/itex]
Then the question asks whether knowing its value for known candles or yardsticks, is a good way to determine the cosmological parameters...
I think that determining it will allow us to determine the redshift [itex]z[/itex] and thus the scale factor [itex]a[/itex] and its evolution. So we can know how [itex]a[/itex] evolves and thus obtain the cosmological parameters from the Friedmann equations. Is that wrong?
However, somewhere I read that the dependence of [itex](1+z)^{-4}[/itex] is independent on the cosmological model ,something that made me think I was wrong... :(
Any idea?