When we view a quasar with a redshift z, this means the wavelengths of light emitted from the quasar have been shifted by z = Δλ \ λ₀. This wavelength shift is: A)a Doppler shift. B)a gravitational redshift. C)a cosmological redshift. D)all three of the above since they are one and the same thing.

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Quizplus · Accepted Answer

A cosmological redshift is caused by the expansion of the universe and results in a shift of the wavelengths of light emitted from a distant object like a quasar. Whereas, a Doppler shift is caused by the motion of the emitting object relative to the observer, and a gravitational redshift is caused by the gravitational pull on the photons emitted from the object. While all three shifts change the wavelengths of light emitted from the quasar, only a cosmological redshift is observed in distant quasars and is a result of the expansion of the universe.

When We View a Quasar with a Redshift Z, This