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StarLab
2004-Aug-24, 06:48 PM
Hello, everyone!

I have been greatly intrigued by the supposed "Great Attractor" story mentioned by a few users; the guidelines being that there is a supergalactic something in the universe of great density that is attracting - and made up of - large amounts of galactic matter.

Because I am no expert at hyperlinking, here are the critical excerpts:

Centaurus Supercluster
The nearest large supercluster. The Centaurus supercluster is a long supercluster containing four rich galaxy clusters - A3526, A3565, A3574 and A3581 as well as hundreds of smaller groups of galaxies. A3526 is the dominant cluster among these and lies 140 million light years away. Seen from a large distance, the Virgo and Hydra superclusters might look like appendages to the Centaurus supercluster. The Centaurus supercluster lies near the 'Great Attractor' - a large collection of matter affecting the motion of our galaxy and others. It is obscured by the plane of our own galaxy, but it is probable that the large cluster A3627 is largely responsible.
A3627 and the hunt for the Great Attractor

In 1987 D Burstein, R Davies, A Dressler, S Faber, D Lynden-Bell, R Terlevich and G Wegner while studying the velocities of galaxies in the nearby universe published evidence in a series of papers ( 1, 2) that there is a large scale motion of galaxies towards the Centaurus region of the sky. They called this region the 'Great Attractor'. Unfortunately the exact location of the object pulling the galaxies is very near to the plane of the Galaxy and hidden by the foreground gas, dust and stars.

Kraan-Korteweg, Woudt, Cayatte, Fairall, Balkowski and Henning reported in a paper in 1996 that there was a large cluster of galaxies in this region which had been previously ignored. This is the A3627 cluster (or the 'Norma cluster'). Careful study of this cluster showed that it is a massive cluster of galaxies similar in scale to the Coma or Perseus clusters. It is therefore the nearest of the very rich clusters which contain thousands of galaxies. It is not an easy cluster to see, and large-angle photographs of this region usually show immense numbers of foreground stars and not much else.

This is not quite the end of the Great Attractor story. Although the A3627 cluster is a massive cluster, it may not be massive enough to cause so many galaxies to move towards it. There is a possibility that there may be a second rich cluster even closer to the plane of the Galaxy and even harder to see. R Kraan-Korteweg and P Woudt report that there is a strong radio source (called PKS1343-601) behind the Milky Way which may be another rich cluster of galaxies.
Being that I cannot post diagrams, maps, photographs or charts, I left out two such additions and their texts. To view these just go to the following site:
http://www.anzwers.org/free/universe/index.html
That is only the home page. One can also type "An Atlas of the Universe" on google, for that is the title of this site.

Please verify this story if you will, introduce any facts on this subject you may know, or introduce new sites on this topic. Thank you for your appreciation. Comments and questions are also appreciated.

P.S.: in addition, do not forget to read the hyperlinked abstract concerning the existence of a particular PKS object.

antoniseb
2004-Aug-24, 07:05 PM
Originally posted by StarLab@Aug 24 2004, 06:48 PM
Please verify this story if you will, introduce any facts on this subject you may know, or introduce new sites on this topic.
One minor tweak to the story as you presented it: The galaxies we observe locally are not moving toward the great attractor, they are simply moving away from it less rapidly than cosmic expansion would noramlly dictate.

At present we don't know a lot about it. There is a thread buried here somewhere with discussions we had a few months ago. It seems fairly safe to assume that it is a gigantic galactic cluster, possibly one with more than its share of dark matter.

If I remember correctly, we have enough information about it now [or very soon] to estimate it's distance and mass fairly accurately [within a factor of two or so]. This would be by observing the motion of other galaxies near it. In any case, someday we will have images of it, but they won't be in the optical wavelengths. It should be possible to see it in the hard xray part of the spectrum, since, if is that massive, it should be glowing pretty brightly.

StarLab
2004-Aug-24, 07:22 PM
Well, obviously, such a collection of mass and matter should have profound significance among the backdrop against the entire universe, should it not?

aries_4_5_48
2004-Aug-26, 05:47 AM
....it could prove to be very interesting if this GAII were proved to be true. The term "attractor" is also applied in the micro world and basically performs the same function. It is the 'point' at which order begins to manifest itself in the midst of chaos. (the orderly framework seen in fractals begins at the "attractor" and grows or multiplies by means of self-similar repetition) I always find it exciting when the same principle works on itty-bitty things as well as great, great, big ones... :rolleyes:

"God plays dice with the Universe, but they're loaded dice." J. Ford :ph34r: