Detecting mysterious dark flows in the universe

As if the mystery of dark matter and dark energy has not been controversial enough, a new question has been discovered about the universe. The array of matter in the universe seems to be moving at a very high level in a uniform direction that cannot be explained by any known gravitational force in the universe. Astronomers call it a 'dark flow' phenomenon .

According to the researchers, what draws matter must lie outside the observed universe.

When they talk about the observed space, they do not mean the truth when viewed with their eyes or even the most advanced telescope. In fact, there exists a fundamental limit on aerospace that we can observe no matter how high-level observation aids are available. The universe is thought to form 13.7 billion years ago. So even if the light starts to reach us immediately after the Big Bang, the longest distance it can travel is 13.7 billion light-years. Perhaps there are distant universes (we don't know how big the universe will be), but we can't see far away by light because light can travel in time the life of the universe.

Mysterious motion

Scientists discovered the flow by studying some of the largest structures in the universe: giant galaxy clusters. They are masses of thousands of galaxies, and hot gases emit X-rays. By observing the interaction of X-rays with the cosmic microwave background (CMB), it is the radiation of the remnants of the explosion. Big Bang, scientists can study the movement of galactic clusters.

Galactic cluster 1E 0657-56 (also called Bullet cluster) is located 3.8 billion light-years away.This is one of hundreds of galaxies clustered by a mysterious flow of matter in the universe.(Photo: NASA / STScI / Magellan / U.Arizona / D.Clowe et al)

X-rays spread photons on CMB, varying the temperature according to the effect of the kinetic Sunyaev-Zel'dovich (SZ) effect. This effect has not been observed before, but a group of researchers led by Alexander Kashlinsky (astrophysicist at Goddard Space Flight Center - NASA) discovered it when they studied. The huge catalog includes 700 galaxy clusters that are as far as 6 billion light-years away or located approximately half the distance of the universe. They compared this category to the CMB map captured by NASA's Wilkinson Microwave Anisotropy Probe (WMAP).

They found that galactic clusters moved at about 2 million miles an hour (3.2 million kilometers an hour) toward the sky between the constellation Centaurus and the Vela constellation. This motion is different from the expansion of the outer universe (driven by the force of dark energy names).

Kashlinsky said: 'We found a significant velocity, besides, this velocity did not decrease with the distance we could measure. The matter in the observed universe cannot create that flow '.

The balloon is inflated

Scientists conclude that what controls the movement of galactic clusters must be outside the known universe.

A hypothesis called 'inflating' suggests that the universe they replaced saw only a small bubble in space - time, which expanded rapidly after the Big Bang. There may be other space beyond this bubble that we can't see.

Hot air in galactic clusters moves (white spots) that change the microwave temperature in the universe.Hundreds of distant clusters seem to be moving in the same direction towards the sky (purple ellipse).(Photo: NASA / WMAP / A. Kashlinsky et al)

In those universes, time space can be very different, and it seems that there are no stars or galaxies (stars and galaxies are only formed because of the dense mass that gathers in our cosmic bubble. ). Maybe that time space contains huge structures larger than anything in our universe. Those structures are what people suspect are enticing galaxies to cause dark flows.

In the telephone interview, Kashlinsky said: 'These motion-causing structures have been pushed away by the inflating process, I estimate that they are hundreds of billions of light years away. We cannot observe them even with the most advanced telescope because the light from that place cannot reach us by the time of the universe. In order to create a cohesive line, they must be very strange structures, perhaps the time space is deformed. But this is just speculation. '

Unexpected discovery

Although the inflating hypothesis predicts many strange aspects of the distant universe, not many scientists predict that there is a dark flow.

Kashlinsky said: 'This is a big surprise for us and I think for the same. With some special inflating models we will predict that there are structures like this. In literature there are also some suggestions that I think have not been seriously considered until now. '

The finding will help scientists explore what happened to the universe before the inflating process, and what is happening in the inviolable territory that we cannot see.

Researchers will publish their findings in the October 20 issue of the Astrophysical Journal Letters.