Local Void

Coordinates: 18h 38m 0s, +18° 0′ 0″

Local Void
Object type void
Observation data
(Epoch J2000.0 [1])
18h 38m [1]
Declination +18.0° [1]

In visual light (V)

Size
60 Mpc (200 Mly) [2]

The Local Void is a vast, empty region of space, lying adjacent to the Local Group.[3][4] Discovered by Brent Tully and Rick Fisher in 1987,[5] the Local Void is now known to be composed of three separate sectors, separated by bridges of "wispy filaments".[4] The precise extent of the void is unknown, but it is at least 45 Mpc (150 million light-years) across[6] and may have a long dimension of up to 70 Mpc (230 million light-years).[4] The Local Void also appears to have significantly fewer galaxies than expected from standard cosmology.[7]

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.[3][8]

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.[3] The Local Void extends approximately 60 megaparsecs (200 Mly), beginning at the edge of the Local Group.[9] It is believed that the distance from Earth to the centre of the Local Void must be at least 23 megaparsecs (75 Mly).[4]

The size of the Local Void was calculated due to an isolated 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.[4] Dark energy has been suggested as an alternative explanation for the speedy expulsion of the dwarf galaxy.[3]

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.[10]

Effect on surrounds

Scientists believe that the Local 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.[8] 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.[4] The Milky Way's velocity away from the Local Void is 270 kilometres per second (600,000 mph).[3][6]

List of void galaxies

Several void galaxies have been found within the Local Void, these include:

This list is incomplete; you can help by expanding it.
Galaxy Void Filament Notes Comments
PC 1357+4641 Boötes void [11] Emission-line Galaxy
IRAS 14288+5255 Boötes void [11] AGN X-ray source
G 1432+5302 Boötes void [12] Starburst galaxy
G 1458+4944 Boötes void [12] LINER galaxy
G 1507+4554 Boötes void [12] Starburst galaxy
G 1510+4727A & G 1510+4727B Boötes void [12] Interacting galaxy pair
BHI 1514+3819 Boötes void [11]
FSS 1515+3823 Boötes void [11]
G 1517+3949 Boötes void [12] Starburst galaxy
G 1517+3956A & G 1517+3956B Boötes void [12] Interacting galaxy pair
IRAS 15195+5050 Boötes void [11] AGN X-ray source
Markarian 845 Boötes void [11] Seyfert 1 (X-ray source)
CG 547 Boötes void [11] Emission-line Galaxy
CG 637 Boötes void [11] Emission-line Galaxy
CG 922 Boötes void [11] Emission-line Galaxy
MCG+01-02-015 [13][14][15][16] LEDA 1852 (Pisces)
Pisces A Local Void [17]
Pisces B Local Void [17]

References

  1. 1 2 3 "NAME LOCAL VOID -- Underdense region of the Universe". SIMBAD. Retrieved 21 December 2014.
  2. ↑ Nakanishi, Kouichiro; Takata, Tadafumi; Yamada, Toru; Takeuchi, Tsutomu T.; Shiroya, Ryuichi; Miyazawa, Morio; Watanabe, Shigeo; Saito, Mamoru (1997). "Search and Redshift Survey for IRAS Galaxies behind the Milky Way and Structure of the Local Void" (PDF). Astrophysical Journal Supplement. 112: 245. Bibcode:1997ApJS..112..245N. doi:10.1086/313039.
  3. 1 2 3 4 5 Shiga, David (1 June 2007). "Dwarf-flinging void is larger than thought". NewScientist.com news service. Retrieved 2008-10-13.
  4. 1 2 3 4 5 6 Tully, R. B.; Shaya, E. J.; Karachentsev, I. D.; Courtois, H. M.; Kocevski, D. D.; Rizzi, L.; Peel, A. (2008). "Our Peculiar Motion Away from the Local Void". The Astrophysical Journal. 676: 184. arXiv:0705.4139Freely accessible. Bibcode:2008ApJ...676..184T. doi:10.1086/527428.
  5. ↑ Tully, R. Brent; Fisher, J. Richard (1987). Nearby Galaxy Atlas. Cambridge University Press.
  6. 1 2 Univ. of Hawaii Institute for Astronomy (12 June 2007). "Milky Way moving away from void". astronomy.com. Retrieved 2008-10-13.
  7. ↑ Peebles, P. J. E.; Nusser, A. (2010). "Nearby galaxies as pointers to a better theory of cosmic evolution". Nature. 465 (7298): 565–569. arXiv:1001.1484Freely accessible. Bibcode:2010Natur.465..565P. doi:10.1038/nature09101. PMID 20520705.
  8. 1 2 I, Iwata; Ohta, K.; Nakanishi, K.; Chamaraux, P.; Roman, A.T. 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.
  9. ↑ Tully, Brent. "Our CMB Motion: The Local Void influence". University of Hawaii, Institute for Astronomy. Retrieved 2008-10-13.
  10. ↑ Moss, Adam; James P Zibin; Douglas Scott (2011). "Precision Cosmology Defeats Void Models for Acceleration". Physical Review D. 83 (10). arXiv:1007.3725Freely accessible. Bibcode:2011PhRvD..83j3515M. doi:10.1103/PhysRevD.83.103515.
  11. 1 2 3 4 5 6 7 8 9 The Astrophysical Journal Letters, "Detection of X-Ray Emission from Galaxies inside the Bootes Void", Chulhee Kim, Th. Boller, Kajal K. Ghosh, Douglas A. Swartz, Brian D. Ramsey, 'Volume 546, Number 2', 10 January 2001, doi:10.1086/318868
  12. 1 2 3 4 5 6 The Astronomical Journal, "Spectroscopy of Galaxies in the Bootes Void", Shawn Cruzen 1, Tara Wehr, Donna Weistrop, Ronald J. Angione, Charles Hoopes, 'Volume 123, Number 1', 2002 January, doi:10.1086/324739
  13. ↑ SIMBAD, MCG+01-02-015
  14. ↑ "The loneliest of galaxies". Hubble Space Telescope. 9 November 2015. Retrieved 10 November 2015.
  15. ↑ Sci-News, "NASA’s Hubble Space Telescope Focuses on Lonely Galaxy", 9 November 2015
  16. ↑ SpaceDaily, "Hubble Views a Lonely Galaxy", 18 November 2015
  17. 1 2 "Hubble Sees Two Dwarf Galaxies in Pisces". Sci-News. 15 August 2016.
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