For some far objects there is a strong red shift due to expansion, if the object was highly affected by a strong gravitational field that lead to affect its movement how can we distinguish between the red shift from expansion and red shift or blue shift that yielded from the fast rotational movement of the object due to being near the highly gravitational field. neglecting the red shift from gravitational field it self. Is the equations of special relativity enough for describing such type of movement?
In general terms, the cosmological redshift imparted to distant light as it traverses expanding spacetime for up to billions of years far exceeds any possible spectral shift that might be imparted due to local gravitational interactions. Observations of nearby various rotating objects, such as spiral galaxies might provide some reference for evaluating the peculiar motions of large scale, compound objects and applied to variations in the observed redshift of similar distant galaxies, but as I understand, other factors such as dispersion of light by intervening dust clouds (and of course the Earth's atmosphere) can also contribute to such variations. As I understand, in general, the redshift imparted by spacetime expansion should be quite consistent for all neighboring objects - variations in the redshift of light from distant objects should be the product of peculiar motions, dust and other more variable factors. I'd expect that any such variations would be relatively tiny compared to cosmological redshift...
Also see http://en.wikipedia.org/wiki/Redshift#Distinguishing_between_cosmological_and_local_effects http://einstein.stanford.edu/content/relativity/a11859.html and https://www.researchgate.net/post/How_is_the_Doppler_red-shift_differentiated_from_gravitational_red-shift - and their references.
Thank you James
But as I understand Its difficult to measure the local Doppler shift for distant galaxies.
Can we use the comparing methods with a nearby objects to know the value of Doppler shift for such far objects. As an example comparing the the object that has high rotational speeds with an object that is with the same distance from us but has neglected motion around its local region?
Sadeem,
I think that the heart of the problem is that there is no way to directly distinguish between any factors that contribute to the redshift of distant objects - we only know that _all_ very distant objects are highly redshifted. The spectral shift of light from any object can only be determined from its net change - the total change in spectral lines observed from specific types of objects - and those expected (based on their elementary composition) from such objects that are relatively stationary and located nearby.
The light from stars in distant spiral galaxies (especially viewed edge-on), for example, should reflect both the spectral shift of their galactic rotation and the common cosmological redshift imparted by the effects of expansion. I don't know whether the differential redshift/blueshift imparted by rotation can be precisely identified within the net redshift observed for all stars in the galaxy: other factors such as intervening dust may make such small distinctions impossible.
I certainly have no expertise in this area, but there is a great deal that is known about the composition of various types of stars, for example, and motions, including orbital rotation and spin. See also http://en.wikipedia.org/wiki/Astronomical_spectroscopy.
Binary stars may also be useful in evaluating the spectral shift imparted by local, peculiar motions and redshift imparted by the metric expansion of spacetime.
My understanding is that the apparent recessional velocity imparted to distant galaxies can seemingly exceed the speed of light - the amount of redshift imparted to distant light by expansion far exceeds any peculiar velocities imparted by gravitation. The most extreme case for analysis might be the relativistic polar jets of distant active galactic nuclei that might be directed towards us, since their velocities can produce very high blueshifts...
Red shift can originate also in following cases.
1) The distance between a source and an observer does not change, but the source moves with velocity comparable with the speed of light. Then red shift in the source spectrum arises. It is interpreted as a result of relativistic slowdown of time on the source relative to the observer (it is called transverse Doppler effect).
2) Red shift arises if the observer is located in a region where the gravitation is less than near the source. In classical physics it means that photons surmount gravitation and thus lose energy. Red shifts in spectra of white dwarfs are explained in this way.
Please read "Expansion of the universe mistake of Edwin Hubble... " in Acta Physica Polonica or on that site under name von Brzeski . there is full answer to your question
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