Starship Asterisk*

According to Atrio-Barandela, who has focused on understanding the possible errors in the team's analysis, the new study provides much stronger evidence that the dark flow is real. For example, the brightest clusters at X-ray wavelengths hold the greatest amount of hot gas to distort CMB photons. "When processed, these same clusters also display the strongest KSZ signature -- unlikely if the dark flow were merely a statistical fluke," he said.

It is interesting that the formation of a dipole was found, indicating a possible origin from the centre of a cluster of galaxies.

Peculiar velocities of clusters of galaxies can be measured by studying the fluc-
tuations in the cosmic microwave background (CMB) generated by the scattering
of the microwave photons by the hot X-ray emitting gas inside clusters. While
for individual clusters such measurements result in large errors, a large statistical
sample of clusters allows one to study cumulative quantities dominated by the
overall bulk flow of the sample with the statistical errors integrating down. We
present results from such a measurement using the largest all-sky X-ray cluster
catalog combined to date and the 3-year WMAP CMB data. We find a strong and
coherent bulk flow on scales out to at least (greater than or equal) 300h-1Mpc, the limit of our catalog.
This flow is difficult to explain by gravitational evolution within the framework
of the concordance LambdaCDM model and may be indicative of the tilt exerted across
the entire current horizon by far-away pre-inflationary inhomogeneities..

Our findings imply that the Universe has a surprisingly coherent
bulk motion out to at least 300h-1Mpc and with a fairly high amplitude of (greater than or equal to)
600-1000 km/sec, necessary to produce the measured amplitude of the dipole signal of ~2-3 microK. Such
a motion is diffcult to account for by gravitational instability within the framework of the
standard concordance LambdaCDM cosmology but could be explained by the gravitational pull of
pre-inflationary remnants located well outside the present-day horizon.

swainy wrote:I just had an thought. I was watching Hawking's Universe. He stated: His idea, BB Theory Came from black holes. If there is a hole in space time, which is a black hole, then that's where matter comes from nothing in the BB Theory.

Chris Peterson wrote:Except, the BB theory does not have matter coming from nothing.

swainy wrote:Here his words. Matter from nothing.
http://www.ted.com/talks/stephen_hawkin ... verse.html

This flow is difficult to explain by gravitational evolution within the framework
of the concordance LambdaCDM model and may be indicative of the tilt exerted across
the entire current horizon by far-away ]pre-inflationary inhomogeneities..

Ann wrote:Anyway. I think I have heard some speculation that the Dark Flow may reflect factors that existed in that "pre-existing universe" or the "pre-existing something" that existed before the Big Bang. If anything at all existed before the Big Bang, of course. I realize that we can't know anything about what, if anything, existed before the Big Bang. Or at least we haven't figured out a way to deduce anything about what may have existed before the Big Bang.

swainy wrote:And this is the last time you will here from me.

A potential portal to other universes seems to have closed. The sharpest map yet made of light from the infant universe shows no evidence of "dark flow" – a stream of galaxy clusters rushing in the same direction that hinted at the existence of a multiverse.

That is the conclusion of 175 scientists working with data from the European Space Agency's Planck spacecraft. But champions of dark flow are not ready to give up yet, including one Planck scientist who says his team's analysis is flawed.

The first suggestion that the flow existed came in 2008, when a group led by Alexander Kashlinsky of NASA's Goddard Space Flight Center in Greenbelt, Maryland, scrutinised what was then the best map of the cosmic microwave background radiation, the big bang's afterglow. NASA's WMAP satellite measured the temperature of this ancient light, revealing fluctuations in the density of matter in the very early universe.

The light's wavelength can also change noticeably when photons are scattered off ionised gas moving through space, providing a way to probe the velocity of such gas. Kashlinsky's WMAP analysis found that hundreds of gas-rich galaxy clusters appeared to be streaming towards a region in the sky between the constellations Vela and Centaurus.

Tilted table

This flow suggested that the universe had somehow become lopsided, as if space-time itself was behaving like a tilted table and matter was sliding off, says Kashlinsky. That goes against the standard model of cosmology, which says that the universe is increasingly uniform on larger scales, making it unlikely that structures big enough to produce such a tilt would form. Some researchers suggested that, instead, other universes could be pulling on matter in ours, creating the flow. But other groups looking at WMAP data did not detect the controversial motion.

The latest search is based on a new, higher-resolution map of the cosmic microwave background from Planck. The Planck team says their multi-pronged analysis also found no evidence of galaxy clusters gushing along in a coherent stream.

"The Planck team's paper appears to rule out the claims of Kashlinsky and collaborators," says David Spergel of Princeton University, who was not involved in the work. If there is no dark flow, there is no need for exotic explanations for it, such as other universes, says Planck team member Elena Pierpaoli at the University of Southern California, Los Angeles. "You don't have to think of alternatives."

But it is too soon to rule out dark flow entirely, argues Fernando Atrio-Barandela at the University of Salamanca in Spain. A member of the Planck team, he withheld his name from his colleagues' paper because he says they overestimated the uncertainty in their measurements, making what might be a subtle signal of dark flow look like mere noise.

"One has to be very careful not to wash the baby out with the bathwater," agrees Kashlinsky. He and Atrio-Barandela are running their own analysis with the new Planck data and expect to have results in just a few months.

• arXiv.org > astro-ph > arXiv:1303.5090 > 20 Mar 2013

• arXiv.org > astro-ph > arXiv:1303.6614 > 26 Mar 2013