# Local Void

The Local Void is a vast, empty region of space, devoid of matter, located within[clarification needed] the Virgo Supercluster and lying adjacent to our own Milky Way galaxy.[1][2] Discovered by Brent Tully of the American Astronomical Society in Honolulu, Hawaii, the Local Void is millions of light years in length, the exact extent of which is unknown.[3] The void is divided into three separate sectors, which are separated by bridges of "wispy filaments".[2] The Local Void has significantly fewer galaxies than predicted by the standard theory of cosmic evolution.[4]

## Location and dimensions

Voids are the result of the way gravity causes matter in the universe to "clump together", herding galaxies into clusters and chains, which are separated by regions mostly devoid of galaxies.[1][5]

Astronomers have previously noticed that the Milky Way sits in a large, flat array of galaxies called the Local Sheet, which bounds the Local Void.[1] The Local Void extends approximately 60 megaparsecs (200 Mly), beginning at the edge of the Local Group.[6] It is believed that the distance from Earth to the centre of the Local Void must be at least 23 megaparsecs (75 Mly).[2]

The size of the Void was calculated due to a lonely dwarf galaxy located inside it. The bigger and emptier the void, the weaker its gravity, and the faster the dwarf should be fleeing the void towards concentrations of matter.[2] Dark energy has been suggested as an alternative explanation for the speedy expulsion of the dwarf galaxy.[1]

An earlier "Hubble Bubble" model, based on measured velocities of Type 1a supernovae, proposed a relative void centred on the Milky Way. Recent analysis of that data, however, suggested that interstellar dust had resulted in misleading measurements.[7]

## Effect on surrounds

Scientists believe that the Void is growing and the Local Sheet, which makes up one wall of the void, is rushing away from the void's centre at 260 kilometres per second.[5] Concentrations of matter normally pull together, creating a larger void where matter is rushing away. The Local Void is surrounded uniformly by matter in all directions, except for one sector in which there is nothing, which has the effect of taking more matter away from that sector. The effect on the nearby galaxy is astonishingly large.[2] The Milky Way's velocity away from the Local Void is 270 kilometres per second (600,000 mph).[1][3]

## References

1. Shiga, David (16:15 01 June 2007). "Dwarf-flinging void is larger than thought". NewScientist.com news service. Retrieved 2008-10-13. Check date values in: |date= (help)
2. Tully, R. B.; Shaya, E. J.; Karachentsev, I. D.; Courtois, H. �L. �N. M.; Kocevski, D. D.; Rizzi, L.; Peel, A. (2008). "Our Peculiar Motion Away from the Local Void". The Astrophysical Journal. 676: 184. Bibcode:2008ApJ...676..184T. doi:10.1086/527428. replacement character in |first4= at position 4 (help)
3. Univ. of Hawaii Institute for Astronomy (June 12, 2007). "Milky Way moving away from void". astronomy.com. Retrieved 2008-10-13.
4. Peebles, P. J. E.; Nusser, A. (2010). "Nearby galaxies as pointers to a better theory of cosmic evolution". Nature. 465 (7298): 565. Bibcode:2010Natur.465..565P. PMID 20520705. doi:10.1038/nature09101.
5. I, Iwata. The Growth of the Local Void and the Origin of the Local Velocity Anomaly. Nearby Large-Scale Structures and the Zone of Avoidance (329 ed.). Astronomical Society of the Pacific. p. 59. Unknown parameter |coauthors= ignored (help)
6. Tully, Brent. "Our CMB Motion: The Local Void influence�". University of Hawaii, Institute for Astronomy. Retrieved 2008-10-13. replacement character in |title= at position 41 (help)
7. Moss, Adam (2011). "Precision Cosmology Defeats Void Models for Acceleration". Physical Review D. 83 (10). Bibcode:2011PhRvD..83j3515M. arXiv:. doi:10.1103/PhysRevD.83.103515. Unknown parameter |coauthors= ignored (help)