Announcing ... 'Dark Flow'

[CraigS]

So, Robh posed the question:

Originally Posted by Robh

But just how much more complicated are things going to get? If dark energy exists, its nature is going to be even more elusive than dark matter.

Well, here's one answer …
Dark statistics

The hypothetical dark flow seen in the movement of galaxy clusters requires that we can reliably identify a clear statistical correlation in the motion of distant objects which are, in any case, flowing outwards with the expansion of the universe and may also have their own individual (or peculiar) motion arising from gravitational interactions.
…
Very large scale observations of the motion of galaxy clusters were proposed by Kashlinsky et al in 2008 to indicate a region of aberrant flow, inconsistent with the general tendency in the motion and velocity expected by the expansion of the universe – and which cannot be accounted for by localized gravitational interactions.
..
On the basis of such findings, Kashlinsky has proposed that inhomogeneities in the early universe may have existed prior to cosmic inflation – which would represent a violation of the currently favored standard model for the evolution of the universe, known as the Lambda Cold Dark Matter (Lambda CDM) model.

So, now we have to contend with 'Dark Flow', the uneven expansion of the Universe !!
The saga continues !!

Cheers

[marki]

Oh Crikey,what next dark fairytales .

[renormalised (Carl)]

Originally Posted by marki

Oh Crikey,what next dark fairytales .

I'm half expecting Darth Vader to turn up with all this talk of "Dark......".

I can just hear him now, "The ability of your telescopes to find dark energy is insignificant when compared to the power of the Force" <<<raspy breath>>>

[renormalised (Carl)]

Everything is becoming "dark" this and that. Now, dark statistics. Well that's only natural considering that the statistics is only as good as those that perform it, the input parameters and the methods they use. Now it's "dark" they'll really stuff it up good and proper

[alpal]

**

[alpal]

There is a video on it:

https://www.youtube.com/watch?v=UHTna9D3nIY

Also Wikipedia:

Dark flow is an astrophysical term describing a possible non-random component of the peculiar velocity of galaxy clusters. The actual measured velocity is the sum of the velocity predicted by Hubble's Law plus a possible small and unexplained (or dark) velocity flowing in a common direction.
According to standard cosmological models, the motion of galaxy clusters with respect to the cosmic microwave background should be randomly distributed in all directions. However, analyzing the three-year Wilkinson Microwave Anisotropy Probe (WMAP) data using the kinematic Sunyaev-Zel'dovich effect, astronomers Alexander Kashlinsky, F. Atrio-Barandela, D. Kocevski and H. Ebeling found evidence of a "surprisingly coherent" 600–1000 km/s[1][2] flow of clusters toward a 20-degree patch of sky between the constellations of Centaurus and Vela.

[Dave2042 (Dave)]

Interesting. I think the idea has been around for a while, but this seems to put some more substance to it.

I'm not an expert at all, but I think one potential counter to this is the suspicion (on the part of some), that the whole universe is actually much, much bigger than the visible universe, and so the characteristics of the visible could be an entirely misleading picture of the universe as a whole, which would seem to make this issue go away.

Fire away at my half-baked thoughts.

[tempestwizz (Brian)]

My simple understanding has it that the galaxies are not MOVING further apart. It's just that the space between them is increasing, hence there is no 'flow' as such.

[alpal]

Originally Posted by Dave2042

Interesting. I think the idea has been around for a while, but this seems to put some more substance to it.

I'm not an expert at all, but I think one potential counter to this is the suspicion (on the part of some), that the whole universe is actually much, much bigger than the visible universe, and so the characteristics of the visible could be an entirely misleading picture of the universe as a whole, which would seem to make this issue go away.

Fire away at my half-baked thoughts.

From my limited understanding of the video -
there must be a very large mass beyond the area in question pulling the galaxies towards it.
The mystery of the universe deepens.

[Dave2042 (Dave)]

Originally Posted by tempestwizz

My simple understanding has it that the galaxies are not MOVING further apart. It's just that the space between them is increasing, hence there is no 'flow' as such.

Yes and no, as I understand it. Generally speaking, cosmic expansion is indeed space getting bigger, and not anything actually moving within space.

However at smaller scales, things definitely move within space.

I thought that the anomalous flows here are indeed things moving towards large but unidentified masses. Any experts out there want to weigh in on whether I'm right?

[xelasnave]

Dave I think you are correct.
I seem to recall it is movement in space.
Google the great attractor.
That should bring up a diagram of the "flow" of the local group.
Alex

[xelasnave]

here is a wiki link for starters

https://en.m.wikipedia.org/wiki/Great_Attractor

[alpal]

Originally Posted by xelasnave

here is a wiki link for starters

https://en.m.wikipedia.org/wiki/Great_Attractor

Thanks for that link.
There is something going on that scientists don't understand.
Dark matter & dark energy really mean that we don't know what they are.
Dark flow is just the same -
another unknown.
The universe is stranger than we could ever have imagined.

cheers
Allan

[xelasnave]

Dont worry I know what is going on but in the interest of avoiding mass panic will keep the truth an absolute secret.
Alex

[alpal]

Originally Posted by xelasnave

Dont worry I know what is going on but in the interest of avoiding mass panic will keep the truth an absolute secret.
Alex

Thanks - better we don't know.

[graham.hobart (Graham stevens)]

so this is distinct from inflationary movement (Hubbles Law?) and the peculiar motion of galaxies in a cluster or super cluster (accounted for by gravity of dark matter?)
Maybe it's time to revise the warm matter hypothesis?!!
Or maybe someone just pulled a giant plug out???!!

[el_draco (Rom)]

Originally Posted by graham.hobart

so this is distinct from inflationary movement (Hubbles Law?) and the peculiar motion of galaxies in a cluster or super cluster (accounted for by gravity of dark matter?)
Maybe it's time to revise the warm matter hypothesis?!!
Or maybe someone just pulled a giant plug out???!!

Or drank to much home brew... Thats how I find the bedroom some days....

[alpal]

[QUOTE=graham.hobart;1248996]so this is distinct from inflationary movement (Hubbles Law?) and the peculiar motion of galaxies in a cluster or super cluster (accounted for by gravity of dark matter?)
Maybe it's time to revise the warm matter hypothesis?!!
Or maybe someone just pulled a giant plug out???!!
[/QUOT

E]




I have heard so many explanations for dark flow -
the most far fetched was another universe unlike ours except
that it has a huge gravitational attraction in the direction mentioned & is pulling
that whole part of the sky towards itself.

Also - could it be an anomaly caused by a large area of empty space making so much dark energy
that it's pushing that area of the sky away from us?

I will try not to lose too much sleep about it.

cheers
Allan

[DarkArts]

I've said this all along: the universe sucks! What's has recently become apparent is that some parts suck more than others.

[alpal]

Originally Posted by DarkArts

I've said this all along: the universe sucks! What's has recently become apparent is that some parts suck more than others.

But is the question of dark flow causing you to lose sleep?