Differential rotation of galaxies

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Are you referring to redshift?
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I am speaking of galaxy rotation. The mesurement of this rotation use red-shift and blue-shift. Take the spectrum of a serie of regions that goes across the galaxy disk. When the galaxy is inclined one side of the galaxy will come in our direction (blue-shift) and the other side will go away from us (red-shift). Making the shift difference between symetric regions (rigth-left same distance from the center) give us a curve for the rotation in function of the distance from the center.

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my question is: will the aberration produce the observe effect on the Can you explain me exactly what is observed with the rotation of galaxie.
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The rotation rate gradually increases from the center to a maximum value and then remains pretty constant the rest of the way. The sharpness of transition from the center is related to the luminosity of the galaxy. Towards the near center of galaxies sudden increases in velocity have been observed, this is thought to be due to a supermassive object at the center.

Applying the inverse square law to the areas near the galactic centers calls for the invention of dark matter to satisfy the accelerations noticed. Since the galaxies tend to exude more stars and material then they should, some have said that matter is created ex nihilo in their centers by some mysterious and unmodelled processes. Is gravitational screening the answer? Does the rotational axis in combination with the finite range of gravity suggest that eventually all of the matter both detectable and hidden can be pulled out of the galaxy?

Thank you Jeremy.
I took a minute and did a search and found a lot of paper on that.
Most rotation curves look very similar:[url] bustard.phys.nd.edu/PH308 [/url]
<img src=" bustard.phys.nd.edu/PH308/galaxies/rotation_curve.gif " border=0>
Mesured rotation curves <img src=" www-xray.ast.cam.ac.uk/~rschmidt/papers/thesis_html/img31.png " border=0>
This one give the formalas for different mass distribution.
[url] www.pas.rochester.edu/~dmw/ast142/Lectures/Lect_16b.pdf [/url]
The constant density, spherical symmetri fit with the rotation of the center part of the galaxy (incresse in velocity) and the 1/r2 density model fit the rest of the curve (constant). Do you know if the change of function happen between the bulge and the disk of the galaxy?


MarkVitrone
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I was not aware of that. Can you give me some explanations?

"Towards the near center of galaxies sudden increases in velocity have been observed, this is thought to be due to a supermassive object at the center."-MV

are you thinking blackholes at the center of the galaxie? if so there is evidence to prove that idea, the fact that they(blackholes) spin can cause the arms of the galaxie we live in!


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Since the galaxies tend to exude more stars and material then they should

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well shouldn't we deal with the matter can we can keep track of now instead of saying what created it, excluded something?


The intuitive mind

From what I read the gravity aberration (infinite range, finite speed) would not explain the rotation of galaxies.
The main factor in the standard model is the total mass and its distrubutions.
Calculation gave 90% of dark matter and 10% for the seeable matter.
I think that we don't see all matter (brown dwarf hydrogen cloud...) but the estimate of the mass of this baryonic dark matter is not enough. OK so invent the non-baryonic matter...

What else? The Meta Model with a limited range for gavity explain the rotation of galaxies. But what about galaxies cluster? How are they held together? And what about those giant elleptical?