High School Difference Between Redshifts of Massive Galaxies & Accelerating Galaxies

[sqljunkey]

How can someone tell the difference between a super massive galaxy's redshift and a galaxy that is accelerating away?

 

[Ibix]

I don't understand the question - "super massive galaxy" is not a term I'm familiar with, and galaxies aren't typically accelerating.

Do you mean how can we distinguish between gravitational redshift from a super massive black hole and cosmological redshift? Because the gravitational redshift from a black hole at the core of a galaxy would be different across the galaxy, and insignificant beyond a barely noticeable fraction of the core. Cosmological redshift is the same for the entire galaxy.

 

[PeroK]

How can someone tell the difference between a super massive galaxy's redshift and a galaxy that is accelerating away?

If you detect light you have one parameter: the measured wavelength. Any "redshift" is inferred from other factors, such as that you are observing a shifted hydrogen spectrum. There is, therefore, nothing inherent in the measured wavelength that tells you anything other than the measured wavelength.

 

[anuttarasammyak]

Say you observe same amount of red-shift for the two galaxies, observe distances of these galaxies from the Earth. The Shorter distance galaxy has stronger intrinsic gravity attraction, with the expanding universe considered.