Dipole repeller

The dipole repeller is a center of effective repulsion in the large-scale flow of galaxies in the neighborhood of the Milky Way, first detected in 2017. [1] [2] [3] It is thought to be represented as a large supervoid, the Dipole Repeller Void.[4]

The Repeller Dipole

Gravitational attraction induces movement towards more dense areas giving the appearance of galaxies moving away from a less dense area, the 'Dipole Repeller' model.

The Local Group of galaxies is moving relative to the cosmic microwave background (CMB) at 631±20 km/s.

There is also a pattern of bulk flow in the motion of neighboring galaxies extending to distances of over 250 megaparsecs (Mpc). There is a known overdensity – the Shapley Supercluster – creating an attraction in the flow of galaxies.

Fundamentally gravitation is always attractive, but if there is an underdense region it apparently acts as a gravitational repeller. That's because there is less attraction in the direction of the underdensity, and the greater attraction due to the higher density in other directions acts to pull objects away from the underdensity. [5]

The repeller appears to be located at a distance of about 220 Mpc and is anticipated to coincide with a void in galaxy density.

That single center of attraction along with a roughly equal single repeller appear to be the most significant contributors to the CMB dipole.

See also

References

  1. ↑ Hoffman, Yehuda; Pomarède, Daniel; Tully, R. Brent; Courtois, Hélène M. (30 January 2017). "The dipole repeller". Nature Astronomy. 1 (2). arXiv:1702.02483. Bibcode:2017NatAs...1E..36H. doi:10.1038/s41550-016-0036.
  2. ↑ Strickland, Ashley. "Milky Way galaxy is being pushed across the universe". CNN. Retrieved 29 July 2017.
  3. ↑ Woollaston, Victoria. "The Milky Way is being pushed through space by a void called the Dipole Repeller". WIRED UK. Retrieved 2017-02-01.
  4. ↑ Camille M. Carlisle (March 2017). "Cosmic Void "Pushes" Milky Way". Sky and Telescope.
  5. ↑ Stegal, Ethan (4 Feb 2017). "Ask Ethan: If Gravity Attracts, How Can The 'Dipole Repeller' Push The Milky Way?". Forbes Magazine.
  • The Dipole Repeller Film produced as part of the publication: "The Dipole Repeller" by Yehuda Hoffman, Daniel Pomarède, R. Brent Tully, and Hélène Courtois, Nature Astronomy 1, 0036 (2017).


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