Filaments and voids

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Structure of the universe

The matter distribution in the universe is similar astronomical observations and simulations according to an irregular large scale honeycomb structure formed by filaments (matter accumulation) and the intervening voids is formed (voids). Filaments (from the Latin filum "thread") are the thread-like connections in the universe between galaxy clusters and superclusters with a higher local galaxy density around huge voids. Voids ( English for gap, empty space ) in astronomy and astrophysics are huge empty spaces between the larger structures of the universe.

Occurrence

The immediate vicinity of the Virgo supercluster , which houses the Milky Way ; you can see several voids between filaments and superclusters
The universe in a billion light years (307 Mpc ) spread around the earth with local superclusters and voids

Any theory about the origin of these structures on the largest scales must explain the formation and arrangement of these voids, which occur with dimensions of around 100 Mpc (Mega parsec ) - which corresponds to 326 million light years.

Assuming the typical speed of a galaxy at about 600 km / s (= 0.002  c ), it would take 163 billion years for a galaxy to completely cross such a cavity, which is twelve times the age of the universe of 13.8 billion years would correspond. As a result, it is extremely unlikely that the voids were caused by outwardly directed proper movements of the galaxies. Rather, the galaxies must have formed relative to the voids roughly where they are now, and the voids reflect the distribution of the galaxies at the time of their formation.

Since baryonic (with radiation interacting "normal") matter in the early Universe was much too homogeneous to gravitationally form such structures, the dark matter that currently appears completely exotic to us, which we can only recognize through its gravitational effect on the galaxy movements, is likely to form structure have worked.

Our Milky Way Galaxy , the Andromeda Galaxy about 2.5 million light years away , the other members of the Local Group and nearby galaxy groups form with the center of the Virgo galaxy cluster in 65 million light years, the center of the Coma cluster ( Abell 1656) and the Leo galaxy cluster (Abell 1367) a huge filament about 300–450 million light years away. The Great Wall may also be part of the Coma Virgo supercluster .

This cobweb-like structure moves to the norma , south of the scorpion , towards the great attractor and the Shapley supercluster behind it .

The only directly visible evidence of filaments so far was provided by a gas cloud around quasar UM287 that is at least 2 million light years in size.

The voids observed directly so far are mostly in the range of 100 million light years in diameter . The largest void so far discovered in 2007 is the Eridanus supervoid . With a diameter of about a billion light years, it has about a thousand times the volume of the usual voids.

Repulsive effect of voids

In a universe with a homogeneously distributed mass, the gravitational forces would locally cancel each other out and there would be no resulting individual acceleration component. In the real universe, however, there are regions with above and below average concentrations of matter, namely galaxy clusters and voids. While galaxy clusters have an attractive force in the direction of this matter, areas with a mass that is missing from the average cause a lack of attraction in the direction of the void and thus a resulting apparent force in the opposite direction.

For the explanation of the velocity vector of our local group of galaxies, in addition to the attraction by the large attractor or the Shapley supercluster , the repulsive effect of a void in the approximate opposite direction must be taken into account. According to more recent calculations, the influence of this repulsion is even greater than the attraction effects of the galaxy clusters, since this motion vector points exactly away from the void, but only approximately in the direction of the mass concentrations.

See also

Web links

Individual evidence

  1. ↑ Planck 2013 Results Papers. (No longer available online.) European Space Agency , archived from the original on March 23, 2013 ; Retrieved December 27, 2013 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.sciops.esa.int
  2. ↑ Astronomers discover the largest cosmic gas cloud so far. It has dimensions of two million light years, but researchers were only lucky to see it: the gas cloud is illuminated by a kind of natural spotlight. In: Zeit Online. Zeit Online GmbH, January 19, 2014, accessed on January 20, 2014 .
  3. ↑ Tim Stephens: Distant quasar illuminates a filament of the cosmic web. Astronomers capture first image of diffuse gas within the network of filaments connecting galaxies in a cosmic web. January 19, 2014, accessed January 20, 2014 .
  4. ↑ Dirk Eidemüller: Void pushes the Milky Way. Retrieved February 6, 2017 .