Dark river

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Panoramic image of the galaxy clusters . The Norma Cluster (and the Great Attractor ) to the right below the Milky Way disk. The dark river is aimed at an area above the Centaurus cluster.

As dark flow ( tight. Dark Flow ) in which it is cosmology a possible pattern in the proper motion of galaxy clusters called. The theory was first discussed in 2008 during an investigation into background radiation .

Theoretical background

The NASA - probe WMAP ( Wilkinson Microwave Anisotropy Probe ) measures fluctuations of the cosmic background radiation in the microwave range , which the big bang have arisen. The movement of galaxy clusters changes the cosmic background radiation, from which its direction and speed can be calculated.

According to the usual assumptions of cosmology , the proper movements of galaxy clusters should be randomly distributed in all directions relative to the cosmic background radiation.

Observation and discovery

At the Goddard Space Flight Center of NASA, the research group led by Alexander Kashlinsky has analyzed the WMAP data. Analysis of the three-year data, using the Sunyayev-Seldowitsch effect, revealed evidence of a surprisingly coherent flow of galaxy clusters, the speed of this movement increasing with distance. Such a galaxy flow can only be caused by a strong gravitational pull, for which no cause is known.

In 2010, the five-year WMAP data were evaluated in a further study. After that, the number of galaxy clusters involved in the “Dark River” doubled from 700 to 1400. The direction of movement of the clusters in each of the four segments shows some deviations, but all segments show a remarkable correspondence.

"We detect motion along this axis, but right now our data cannot state as strongly as we'd like whether the clusters are coming or going"

- Alexander Kashlinsky
The dark river. The colored dots are clusters of galaxies within one of four distances. The colored ellipses show the direction of common motion for the galaxy clusters of the corresponding color.

Attempted explanation

The authors of the study suggested that the movement is a remnant of the influence of areas of the universe no longer visible today, before cosmic inflation .

"Because the dark flow already extends so far, it likely extends across the visible universe"

- Alexander Kashlinsky

criticism

The astrophysicist Edward L. Wright published arguments about the flawedness of the study, to which the authors responded immediately. Ryan Keisler published a study in 2009, according to which the dark flow is not a physical phenomenon because the primary anisotropy of the cosmic background radiation was not taken into account in the study .

According to the Goddard Space Center, it can be an effect of a neighboring universe or a space-time region that is fundamentally different from the observable universe. The data from over 1000 galaxy clusters were measured up to a distance of three billion light years. According to Kashlinsky, these measurements are no statistical coincidence.

"At this point we don't have enough information to see what it is, or to constrain it. We can only say with certainty that somewhere very far away the world is very different than what we see locally. Whether it's 'another universe' or a different fabric of space-time we don't know. "

- Alexander Kashlinsky

In 2011, 557 supernovae from the Union2 dataset were examined in a study  . After that, these objects do not show any synchronous movement, but their behavior corresponds to the Lambda CDM model .

In 2013, the data from the Planck satellite of the European Space Agency also showed no evidence of the dark river postulated by Kashlinsky.

See also

literature

  • A. Kashlinsky, F. Atrio-Barandela, D. Kocevski, H. Ebeling: A measurement of large-scale peculiar velocities of clusters of galaxies: results and cosmological implications. In: The Astrophysical Journal . tape 686 , no. 2 , October 2008, p. L49-L52 , doi : 10.1086 / 592947 .
  • A. Kashlinsky, F. Atrio-Barandela, D. Kocevski, H. Ebeling: A measurement of large-scale peculiar velocities of clusters of galaxies: technical details . In: The Astrophysical Journal . tape 691 , no. 2 , February 2009, p. 1479-1493 , doi : 10.1088 / 0004-637X / 691/2/1479 .
  • A. Kashlinsky, F. Atrio-Barandela, H. Ebeling, A. Edge, and D. Kocevski: A New Measurement of the Bulk Flow of X-Ray Luminous Clusters of Galaxies . In: The Astrophysical Journal . tape 712 , no. 1 , February 2010, p. L81-L85 , doi : 10.1088 / 2041-8205 / 712/1 / L81 .
  • F. Atrio-Barandela, A. Kashlinsky, H. Ebeling, D. Kocevski, A. Edge: The Error Budget of the Dark Flow Measurement . In: The Astrophysical Journal . tape 719 , no. 77 , August 2010, p. 77-87 , doi : 10.1088 / 0004-637X / 719/1/77 ( kashlinsky.info [PDF]).
  • A. Kashlinsky, F. Atrio-Barandela, H. Ebeling: Measuring bulk motion of X-ray clusters via the kinematic Sunyaev-Zeldovich effect: summarizing the “dark flow” evidence and its implications . February 2012, p. 172 , arxiv : 1202.0717 ( kashlinsky.info [PDF]).
  • De-Chang Dai, WH Kinney, D. Stojkovic: Measuring the cosmological bulk flow using the peculiar velocities of supernovae . In: Journal of Cosmology and Astroparticle Physics . No. 4 , April 2011, doi : 10.1088 / 1475-7516 / 2011/04/015 , arxiv : 1102.0800 .

Individual evidence

  1. ^ John Roach: New Proof Unknown "Structures" Tug at Our Universe. National Geographic News, March 22, 2010; accessed April 28, 2012 .
  2. ↑ Mysterious cosmic 'dark flow' tracked deeper into universe. ScienceDaily, March 10, 2010, accessed April 27, 2012 .
  3. ↑ Reddy, Francis and Chandler, Lynn: Mysterious Cosmic 'Dark Flow' Tracked Deeper into Universe. Goddard Space Flight Center, March 10, 2010, accessed April 27, 2012 .
  4. ↑ a b N. Atkinson: Scientists Detect “Dark Flow:” Matter From Beyond the Visible Universe. Universe Today, September 23, 2008; accessed April 27, 2012 .
  5. ^ Edward L. Wright: Dark Flow Detected - Not! Ned Wright's News, September 24, 2008, accessed April 28, 2012 .
  6. ↑ Alexander Kashlinsky: RNed Wright detects "errors" - NOT! Sasha Kashlinsky - Projects, September 29, 2008, accessed April 28, 2012 .
  7. ↑ Ryan Keisler: The Statistical Significance of the "Dark Flow" . In: Cornell University . October 2009, arxiv : 0910.4233 .
  8. ^ Supernovae Cosmological Project, Introduction to the SCP Union 2.1 Compilation. April 15, 2011, accessed April 29, 2012 .
  9. ↑ Is an Adjacent Universe Causing the Dark Flow of Hundred of Millions of Stars at the Edge of the Observable Universe? Or, Might It Be Something Else. The Daily Galaxy, April 15, 2011, accessed April 29, 2012 .
  10. ↑ Adam Mann: Supernova research challenges cosmic "dark flow" mystery. ars technica, January 15, 2012, accessed April 29, 2012 .

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