New Attractor, New Repeller

Discussions ranging from space technology, near-earth and solar system missions, to efforts to understand the large-scale structure of the cosmos.

New Attractor, New Repeller

Postby BurtJordaan on March 14th, 2017, 2:51 am 

Thought the Great Attractor sounded formidable? Well, think again - the more distant Shapley Attractor is now dwarfing it. As redshift data of thousands of 'nearby' galaxies were compiled and refined, no sooner had Shapley claimed the superior role, or a new phenomenon showed up, one that seems to be even more powerful: the Dipole Repeller.

Dipole Repeller.png
Shapley Attractor and Dipole Repeller (https://vimeo.com/189355968)


OK, it seems that they work together, the one "pulls" and the other one "pushes" our local group of galaxies, with a 'peculiar flow vector' (the yellow arrow)[1] of 630 km/s, almost directly away from the Dipole Repeller. The vector is probably the result of a combination of the more local pulls and the big "pullers and pushers" farther out. So what is a 'pusher', or rather a repeller?

I'm no astronomer (not even an amateur one), but as I understand things, astronomers combine the redshift data of the area of interest with other observations, e.g. mass densities, into a computer program to provide a 3D density map, as in the colors of the image. Using this, together with observed redshifts, they then model the motion of near-massless particles that they "seeded" the background with. This gives the flow-arrows as pictured. The animation in https://vimeo.com/189355968 is stunning!

The Dipole Repeller is just the minimum average density point of a large area of under-density, called a 'void'. In terms of gravitational potential, the repeller is a local maximum (gravity 'bump') and the attractor a local minimum (gravity 'well') for the area of interest.

Enjoy! (before we discuss this amazing result further).

Notes:
[1] Peculiar flow is our motion relative to the local inertial frame in which the CMB temperature would be the same in all directions, i.e. isotropic,
Last edited by BurtJordaan on March 27th, 2017, 3:38 am, edited 5 times in total.
Reason: End notes, clarification
User avatar
BurtJordaan
Forum Moderator
 
Posts: 2074
Joined: 17 Oct 2009
Location: South Africa
Blog: View Blog (7)
dandelionDave_Oblad liked this post


Re: New Attractor, New Repeller

Postby BurtJordaan on March 15th, 2017, 1:31 am 

BurtJordaan » 14 Mar 2017, 08:51 wrote:The Dipole Repeller is just the minimum average density point of a large area of under-density, called a 'void'. In terms of gravitational potential, the repeller is a local maximum (gravity 'bump') and the attractor a local minimum (gravity 'well') for the are of interest.

If you look at the potential values on the video frame above, it looks like it is the opposite of what I wrote above. The potential of the Attractor is given as Phi = +955 and for the Repeller Phi = -650. I had to read the technical article to find out why, because the gravitational potential function Phi is normally maximally negative at the center of a mass (a local Attractor) and can at most be zero in distant, empty space.

It appears that they are using the gravitational field strength as a potential that they call Phi - the potential to cause a flow velocity. A positive Phi then causes inflow into an Attractor, while there is obviously a negative inflow for a Repeller.

It is good to note that the Repeller is not creating any force, it is just a flow from higher (gravitational) potential energy to lower potential. This is why I like my interpretation more - it is rather intuitive... ;)
Last edited by BurtJordaan on March 15th, 2017, 6:01 am, edited 1 time in total.
Reason: Added paragraph
User avatar
BurtJordaan
Forum Moderator
 
Posts: 2074
Joined: 17 Oct 2009
Location: South Africa
Blog: View Blog (7)


Re: New Attractor, New Repeller

Postby curiosity on March 26th, 2017, 6:34 pm 

I have been expecting a torrent of posts in regard to this.... "Come on guys, give me something good to read."
It's a fascinating subject, yet it has been met with a wall of silence ???
curiosity
Member
 
Posts: 331
Joined: 19 Jul 2012


Re: New Attractor, New Repeller

Postby BurtJordaan on March 27th, 2017, 3:40 am 

I think many of the usual contributors are still busy deciding how it all fits into their personal theories... ;)
User avatar
BurtJordaan
Forum Moderator
 
Posts: 2074
Joined: 17 Oct 2009
Location: South Africa
Blog: View Blog (7)


Re: New Attractor, New Repeller

Postby Eclogite on March 27th, 2017, 5:43 am 

curiosity » Sun Mar 26, 2017 10:34 pm wrote:I have been expecting a torrent of posts in regard to this.... "Come on guys, give me something good to read."
It's a fascinating subject, yet it has been met with a wall of silence ???
While I like to think of myself as open minded and far ranging in my beliefs and interests, I must confess to be being basically parochial.

I 'm not too interested in anything beyond the Local Group of galaxies, or further back in time than when the first planetary systems started to form. It's within that milieu that life as we know it evolved and intelligence emerged. The rest is as relevant as plate tectonic mechanisms to a Mayan high priest.

Brilliant work, but it doesn't turn me on. (Loved the graphic.)
Eclogite
Forum Moderator
 
Posts: 1280
Joined: 07 Feb 2007
Location: Around and about


Re: New Attractor, New Repeller

Postby vivian maxine on March 27th, 2017, 8:32 am 

Well, the cat holding it all together gets my attention. How many see him?

Seriously, though, one of us really is interested. Why? I don't understand it. I'm strange, I know, but I love digging into something I have absolutely no understanding of and see if I can make some little sense of it. It's just me. Anything new gets my attention at least long enough to see what I can make of it. That and the fact that "what's out there?" keeps me awake nights. :-)

All that is no help to the OP at all. I'm sorry.
vivian maxine
Resident Member
 
Posts: 2609
Joined: 01 Aug 2014


Re: New Attractor, New Repeller

Postby vivian maxine on March 27th, 2017, 12:22 pm 

Burt, after reading more - the article and some things from Wikipedia - I am wondering something. Does every supercluster have an attractor that pulls on nearby clusters which, in turn, pull in nearby galaxies with their own lesser attractors? And maybe those galaxies also have still lesser attractors that bring in stars and solar systems from nearby? In other words, is this part of a universe-wide system? And - more important - is all of this a picture of what gravity is doing?

Yet, if that is fact, we lose the theory that the entire universe is expanding, don't we? Instead, we have the theory of the final crush at a center.

Am I making sense?
vivian maxine
Resident Member
 
Posts: 2609
Joined: 01 Aug 2014



Return to Astronomy & Cosmology

Who is online

Users browsing this forum: No registered users and 7 guests