Paradoxes Resolved, Origins Illuminated - Lensing Effect for Stars Near Sagittarius A*
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 Lensing Effect for Stars Near Sagittarius A*
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Thomas

United Kingdom
181 Posts

Posted - 23 May 2009 :  11:16:08  Show Profile  Visit Thomas's Homepage  Reply with Quote
Recently, Dr. H.E. Dowdye pointed me to his web page http://www.extinctionshift.com/SignificantFindings08.htm where he gives examples of astrophysical objects where gravitational lensing should be expected but is not observed (I noticed that he posted the link also in this forum a while ago, but I didn't want to revive a thread almost two years old).

The case of the Sombrero nebula addressed on this page is not really that conclusive in my opinion as the effect should be too small to be obvious, but the stars near the supermassive object at the centre of our galaxy should be dramatically affected by the corresponding gravitational lensing:

the stars are orbiting the supermassive object (which has a mass of 4*10^6 solar masses) within a distance of about 10 light days, which corresponds to a distance of 2.6*10^11 km or 3.7*10^5 solar radii. This means that the gravitational deflection for these stars should be 4*10^6/ 3.7*10^5 /2 = 5 times larger than the gravitational deflection near the sun's limb i.e. about 9" (arcseconds) (the additional factor 1/2 in the ratio comes from the fact that the light is produced within the gravitational field and does not come from outside like for the solar case). Since 10 light days at a distance of 26,000 light years corresponds to an angle of 0.2" (see also http://www.astrophysicsspectator.com/tables/MilkyWayCentralStars.html ). This means that, according to GR, we should see the stars actually at a distance 45 times further from the galactic centre than they appear to be. This clearly falsifies not only GR, but they idea of light being affected by masses altogether.

I just wonder whether anybody knows if this point has been addressed somewhere within the framework of GR. Or has this just been ignored so far? Despite a lot of searching on the web, I could not find any reference to this at all.

Thomas

________________________________

Just an update and correction on this:

I did recently a more thorough derivation of the gravitational lensing effect for objects close to the lensing mass, and it turned out that my estimate above is actually incorrect: the value I gave holds strictly speaking only if the if the lensed star is far behind the lensing mass (as compared to our distance from the latter). If it is much closer on the other hand, it has to be multiplied by a factor r/d where r is the distance of the lensed star from the galactic center and d our distance from the latter (this is straightforward to show by using the cosine and sine laws for the corresponding triangle).

With this, the lensing effect on the stars surrounding the galactic center mass becomes obviously much too small to be observable, but it still leaves the possibility that the lensing (or its absence) could be observed for stars a suitable distance behind the galactic center (i.e. far enough to get a large enough lensing effect, and close enough to have sufficiently short orbital periods so that the effect can be observed within a reasonable time period (e.g. a few years)).

Thomas

Edited by - Thomas on 13 Feb 2010 09:52:55

Jim

1831 Posts

Posted - 24 May 2009 :  11:23:38  Show Profile  Reply with Quote
Could this missing effect also suggest the supermass at the center of the galatic disk does not exist?
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Larry Burford

USA
2190 Posts

Posted - 24 May 2009 :  12:26:15  Show Profile  Reply with Quote
Jim,

That is one possibile explanation, but then what are all of those stars orbiting?
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Jim

1831 Posts

Posted - 24 May 2009 :  20:33:58  Show Profile  Reply with Quote
LB, By "all those staes" I assume you mean the stars in the galatic disk. The dynamics of a disk structure forced by gravity needs to be examined with an understanding the disk has mass that is not located anyway near the middle of the disk. The mass of a galaxy is spread out all over the disk which means using the rules that work pretty well for a system like the solar system where 99.9% of the mass is located at the central star won't work at all. New rules need to be worked out to understand the dynamics of a galatic structure.
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Thomas

United Kingdom
181 Posts

Posted - 25 May 2009 :  05:39:27  Show Profile  Visit Thomas's Homepage  Reply with Quote
quote:
Originally posted by Jim

LB, By "all those staes" I assume you mean the stars in the galatic disk. The dynamics of a disk structure forced by gravity needs to be examined with an understanding the disk has mass that is not located anyway near the middle of the disk. The mass of a galaxy is spread out all over the disk which means using the rules that work pretty well for a system like the solar system where 99.9% of the mass is located at the central star won't work at all. New rules need to be worked out to understand the dynamics of a galatic structure.



No, with "all those stars" Larry and I mean those in Fig.9 on the page http://www.extinctionshift.com/SignificantFindings08.htm . The motion of these stars is only consistent with a supermassive object of 4 miilion solar masses. But if one plugs the corresponding values into the lensing formula, one finds that the stars should not appear that close to the center, but 45 times further away.

Thomas
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Jim

1831 Posts

Posted - 25 May 2009 :  10:35:23  Show Profile  Reply with Quote
Thomas, Your Fig9 looks to me like a cartoon because the orbiting stars are moving too far too fast. How fast are these stars going?
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Thomas

United Kingdom
181 Posts

Posted - 26 May 2009 :  15:48:12  Show Profile  Visit Thomas's Homepage  Reply with Quote

Jim, first of all, it is not my figure, but I am just referring to it as an illustration.
And of course this is not a real-time movie, but one based on the positions over a period of more than 10 years (as you can see from the year numbers in the top left hand corner).

Thomas

Edited by - Thomas on 26 May 2009 15:48:44
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Thomas

United Kingdom
181 Posts

Posted - 26 May 2009 :  15:48:12  Show Profile  Visit Thomas's Homepage  Reply with Quote
919117781

Edited by - Thomas on 26 May 2009 15:48:44
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Jim

1831 Posts

Posted - 26 May 2009 :  19:21:22  Show Profile  Reply with Quote
Thomas, Also there is a yardstick of 10 light days that is supposed to give the scale of the orbits. So, why not take all of it to be nothing more than a cartoon based on the imagination of the artist? Where's the data indicating any observation is involved? If there are pictures of SagA why not publish them?
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Thomas

United Kingdom
181 Posts

Posted - 28 May 2009 :  15:08:43  Show Profile  Visit Thomas's Homepage  Reply with Quote
Jim, The second reference I gave above in my opening post mentions some relevant publications.
See also http://www.mpe.mpg.de/www-ir/GC/ from which the image on Dr, Dowdye's website was taken.

Thomas
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Jim

1831 Posts

Posted - 28 May 2009 :  22:30:07  Show Profile  Reply with Quote
Thomas, You were making a point about lensing effects and it seems I upset the apple cart here-I'm sorry and it was unintended. It isn't important to your point which is different than I was thinking at the time.
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Thomas

United Kingdom
181 Posts

Posted - 13 Feb 2010 :  09:38:19  Show Profile  Visit Thomas's Homepage  Reply with Quote
Just an update and correction on this:

I did recently a more thorough derivation of the gravitational lensing effect for objects close to the lensing mass, and it turned out that my estimate above is actually incorrect: the value I gave holds strictly speaking only if the if the lensed star is far behind the lensing mass (as compared to our distance from the latter). If it is much closer on the other hand, it has to be multiplied by a factor r/d where r is the distance of the lensed star from the galactic center and d our distance from the latter (this is straightforward to show by using the cosine and sine laws for the corresponding triangle).

With this, the lensing effect on the stars surrounding the galactic center mass becomes obviously much too small to be observable, but it still leaves the possibility that the lensing (or its absence) could be observed for stars a suitable distance behind the galactic center (i.e. far enough to get a large enough lensing effect, and close enough to have sufficiently short orbital periods so that the effect can be observed within a reasonable time period (e.g. a few years)).

Thomas


Edited by - Thomas on 13 Feb 2010 09:53:16
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Stoat

United Kingdom
964 Posts

Posted - 14 Feb 2010 :  04:31:17  Show Profile  Reply with Quote
Hi Thomas, we were just talking about the star S2 which gets into about 180 a.u. of the super massive object. What are your thoughts on it? It's fifteen solar masses, so it can't be very old. It must be distorted by its close approach, why doesn't it explode?

Also, what do you make of the idea of a neutrino ball?

(Edited)A sudden thought, I simply cannot resist using the splendid barbarism, "periblackholeion"

Edited by - Stoat on 14 Feb 2010 05:02:39
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Thomas

United Kingdom
181 Posts

Posted - 14 Feb 2010 :  06:17:34  Show Profile  Visit Thomas's Homepage  Reply with Quote
Hi Stoat,

quote:
Originally posted by Stoat

Hi Thomas, we were just talking about the star S2 which gets into about 180 a.u. of the super massive object. What are your thoughts on it? It's fifteen solar masses, so it can't be very old.


I can't see the stars surrounding the supermassive object getting very old. Their orbits will be disturbed so much by their mutual close encounters that eventually they will fall into the central object. They will then either be replaced by other stars being captured or by new stars forming in the region.


quote:
Originally posted by Stoat
It must be distorted by its close approach, why doesn't it explode?



I doubt that it will be distorted much, but even if, why should they explode then?. There are double stars that are orbiting much more closely and that are distorted so much that material flows from one to the other, yet still they don't explode. Stars are just balls of plasma (basically protons and electrons) with a luminous atmosphere (see my page http://www.plasmaphysics.org.uk/research/sun.htm ).

quote:
Originally posted by Stoat
Also, what do you make of the idea of a neutrino ball?



You mean for the central object? I don't know about the theory of neutrino stars, but as far as I am concerned, it can as well be just normal matter. If you take the theory under the link I gave above and also at http://www.plasmaphysics.org.uk/research/starformation.htm , then it should be evident that even an object with a mass of a few million masses will be stable in equilibrium.
The point is that such massive objects will have such a high temperature due to the associated gravitational energy (as shown under the above links) that there will be very little light emitted in the visible region. Most of it will be x-rays and gamma-rays. This is why you don't see the central object in the visible and infrared. However, in x-rays the central object is visible (see http://apod.nasa.gov/apod/ap000120.html ) i.e. it is not a black hole (although other people may argue that it is just the surrounding gas that is emitting the x-rays).

Thomas

Edited by - Thomas on 14 Feb 2010 06:18:28
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Stoat

United Kingdom
964 Posts

Posted - 15 Feb 2010 :  14:31:49  Show Profile  Reply with Quote
Hi Thomas, I#'d be very interested in hearing your ideas on the temperature at the Schwarchild radius. Is it gravitationally "hot" but e.m. cold for instance? What do you make of it when it's slung into the lorentzian, as t_r/t = sqrt(1 - r_s/r)
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Stoat

United Kingdom
964 Posts

Posted - 18 Feb 2010 :  04:54:51  Show Profile  Reply with Quote
I wonder if it's possible that the elliptical orbit of S2 is a relativistically altered parabolic trajectory? As far as I know, the theory of what's bringing stars in is another super massive black hole. i haven't looked at the masses of the other close stars but they all look like big brutes. They burn their fuel fast, and they'll already will have a lot of heavier elements. Are sol mass stars eaten or flung out? do massive stars have time to come in from the galactic halo? That question of the rosetta orbit of S2 also intrigues me.

I suppose we could wait and see but all this talk of neutrino balls suggests to me at any rate that the physics near the galactic centre is going to hammered into an Einstein model at whatever cost.

Anyway, a parabolic trajectory, capture or escape trajectory, v = sqrt(2GM/r) the same as the Scwartzchild radius equation where v is c. We can also throw 2GM/rc^2 into the lorentzian.

I do think that metaresearch should do some work on this, rather than wait.

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Jim

1831 Posts

Posted - 18 Feb 2010 :  13:47:16  Show Profile  Reply with Quote
In researching S2(the object said to be nearest the galatic center) it seems Kepler's model is being used to determine most of data rather than observations. The observations are made in just a small part of the spectrum and in very narrow window less than a few arcsec in diameter. Can you tell how so much can be determined about those objects by so little observed data points? Is it not like reading tea leaves or grasping at straws? I think a lot can be learned from observing the galatic center but using a model to determine what the observations are is not very bright.
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Stoat

United Kingdom
964 Posts

Posted - 19 Feb 2010 :  12:50:33  Show Profile  Reply with Quote
Hi Jim, no it is real data. They've got the complete orbit of S2 but we'll have to wait for more data for other star orbits. Not long though, as they're really motoring round. A fifteen year orbit for S2, it's doing about two percent of light speed!
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Jim

1831 Posts

Posted - 19 Feb 2010 :  13:32:48  Show Profile  Reply with Quote
Sloat, Maybe the data indicates a star in an orbit but its not at all clear that is the truth from just data. The data is being fitted to the Kepler model-you can clearly see this if care is taken in reading the article. Its so small a sample of spectral data they had to reject a lot of data that didnot fit within the model. All in all not a good way to do science although lots a science is done this way. Hopefully in the future some thought will be given to observed details that don't fit the whatever favored model is used. I ask you how is this practice any different than what was done a 1,000 years ago?
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Thomas

United Kingdom
181 Posts

Posted - 25 Feb 2010 :  16:40:40  Show Profile  Visit Thomas's Homepage  Reply with Quote
quote:
Originally posted by Stoat

Hi Thomas, I#'d be very interested in hearing your ideas on the temperature at the Schwarchild radius. Is it gravitationally "hot" but e.m. cold for instance? What do you make of it when it's slung into the lorentzian, as t_r/t = sqrt(1 - r_s/r)



Stoat,

I have not been implying that the central object is a black hole (which in my opinion don't exist anyway, considering the theoretical flaws in GR). As I said in my previous post, the reason the object is apparently not emitting any visible light is simply due to its high temperature (which in turn is related to the high gravitational potential energy of the object (assuming it has a mass of several million solar masses)). The radiation is only emitted in the x-ray and gamma ray region (because this is the typical radiation that plasma particles of such high energy would be emitting if they recombine).


Thomas
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