Local Void

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Local Void
The Local Void.gif
Map of voids and superclusters within 500 million light years from Milky Way. The Local Void in the yellow circle.
Object type Void   OOjs UI icon edit-ltr-progressive.svg
Observation data
(Epoch J2000.0 [1] )
Constellation Hercules   OOjs UI icon edit-ltr-progressive.svg
18h 38m [1]
Declination +18.0° [1]
In visual light (V)
Size
60 Mpc (200 Mly) [2]
[ edit on Wikidata]

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 possibly 150 to 300 Mpc. [7] [8] The Local Void appears to have significantly fewer galaxies than expected from standard cosmology. [9]

Contents

Location and dimensions

Voids are affected by 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, yet the exact mechanisms are subject to scientific debate. [3] [10]

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. [11] 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 known as ESO 461-36 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, yet discrepancies give room for competing theories. [4] Dark energy has been suggested as one 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. [12]

Several authors have shown that the local universe up to 300 Mpc from the Milky Way is less dense than surrounding areas – by 15–50%. This has been called the Local Void or Local Hole. [7] [8] Some media reports have dubbed it the KBC Void, [13] although this name has not been taken up in other publications.[ citation needed ]

Effect on surroundings

Scientists believe that the Local Void is growing and that the Local Sheet, which makes up one wall of the void, is rushing away from the void's centre at 260 kilometres per second (160 mi/s). [10] 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 970,000 kilometres per hour (600,000 mph). [3] [6]

List of void galaxies

Several void galaxies have been found within the Local Void. These include:

GalaxyConstellationDeclinationDistanceRight ascensionNotes
Pisces A Pisces +10° 48′ 47.01″18.4 Mly (5.64 Mpc)00h 14m 46.000sThe two void dwarf galaxies located in the Local Void and are in the Pisces constellation. Pisces A is 18.4 million light-years (5.64 megaparsecs) away and Pisces B is 30 million light-years (9.2 megaparsecs) away. The galaxies were discovered with the WIYN Observatory. About 100 million years ago, they started moving out of the void and into the local filament zone and denser gaseous environment. This sparked off a doubling of the rate of star formation. [14]
Pisces B +11° 07′ 18.22″30 Mly (9.2 Mpc)01h 19m 11.700s
NGC 7077 Aquarius 02° 24′ 51″56 Mly (17.2 Mpc)21h 29m 59.6sA lenticular blue compact dwarf galaxy located about 56 million light-years away from Earth in the constellation Aquarius. Discovered by astronomer Albert Marth on 11 August 1863, the galaxy lies within the Local Void. [15]
NGC 6503 Draco +70° 08′ 39.587″13.05 ± 0.33 Mly (4.0 ± 0.1 Mpc)17h 49m 26.4207sA field [16] dwarf spiral galaxy located at the edge of a region of space called the Local Void. The dwarf galaxy spans 30,000 light-years and lies approximately 17 million light-years away in the constellation of Draco (the Dragon). This spiral galaxy is especially colorful where bright red regions of gas can be seen scattered through its spiral arms. Bright blue regions contain stars that are forming. Dark brown dust areas are in the galaxy's arms and center. It has one known satellite galaxy, known as KK 242. With a stellar mass of about 3 million solar masses, KK 242 is on the border between a dwarf irregular galaxy (dIrr) and a dwarf spheroidal galaxy (dSph). [17]
NGC 6789 +63° 58′ 23″12 Mly (3.6 Mpc)19h 16m 41sAn irregular galaxy in the constellation Draco. It was discovered by Lewis Swift on 30 August 1883. It is located within the Local Void, a region of space with far fewer galaxies than its surroundings. It is the nearest blue compact dwarf (BCD) galaxy to the Milky Way. It is chemically homogeneous and relatively metal-poor. [18]

See also

Related Research Articles

<span class="mw-page-title-main">IC 342/Maffei Group</span> Galaxy cluster in the constellation of Cassiopeia

The IC 342/Maffei Group corresponds to one or two galaxy groups close to the Local Group. The member galaxies are mostly concentrated around either IC 342 or Maffei 1, which would be the brightest two galaxies in the group. The group is part of the Virgo Supercluster. However, recent studies have found that the two subgroups are unrelated; while the IC 342 group is the nearest galaxy group to the Milky Way, the Maffei 1 group is several times farther away, and is not gravitationally bound to the IC 342 group.

<span class="mw-page-title-main">Virgo Supercluster</span> Galactic supercluster containing the Virgo Cluster

The Virgo Supercluster or the Local Supercluster is a mass concentration of galaxies containing the Virgo Cluster and Local Group, which itself contains the Milky Way and Andromeda galaxies, as well as others. At least 100 galaxy groups and clusters are located within its diameter of 33 megaparsecs. The Virgo SC is one of about 10 million superclusters in the observable universe and is in the Pisces–Cetus Supercluster Complex, a galaxy filament.

<span class="mw-page-title-main">Sombrero Galaxy</span> Galaxy in the constellation Virgo

The Sombrero Galaxy is a peculiar galaxy of unclear classification in the constellation borders of Virgo and Corvus, being about 9.55 megaparsecs from the Milky Way galaxy. It is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster. It has an isophotal diameter of approximately 29.09 to 32.32 kiloparsecs, making it slightly bigger in size than the Milky Way.

<span class="mw-page-title-main">Hydra–Centaurus Supercluster</span> Closest neighboring galaxy supercluster

The Hydra–Centaurus Supercluster, or the Hydra and Centaurus Superclusters, is a supercluster in two parts, the closest neighbour of Virgo Supercluster. It is located about 39 Mpc (127 Mly) away.

<span class="mw-page-title-main">Dwarf galaxy</span> Small galaxy composed of up to several billion stars

A dwarf galaxy is a small galaxy composed of about 1000 up to several billion stars, as compared to the Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is sometimes classified as a dwarf galaxy; others consider it a full-fledged galaxy. Dwarf galaxies' formation and activity are thought to be heavily influenced by interactions with larger galaxies. Astronomers identify numerous types of dwarf galaxies, based on their shape and composition.

<span class="mw-page-title-main">Milky Way</span> Galaxy containing the Solar System

The Milky Way is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term Milky Way is a translation of the Latin via lactea, from the Greek γαλαξίας κύκλος, meaning "milky circle". From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Doust Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies.

<span class="mw-page-title-main">IC 342</span> Spiral galaxy in the constellation Camelopardalis

IC 342 is an intermediate spiral galaxy in the constellation Camelopardalis, located relatively close to the Milky Way. Despite its size and actual brightness, its location behind dusty areas near the galactic equator makes it difficult to observe, leading to the nickname "The Hidden Galaxy", though it can readily be detected even with binoculars. If the galaxy were not obscured, it would be visible by naked eye. The dust makes it difficult to determine its precise distance; modern estimates range from about 7 million light-years (Mly) to about 11 Mly. The galaxy was discovered by William Frederick Denning in 1892. It is one of the brightest in the IC 342/Maffei Group, one of the closest galaxy groups to the Local Group. Edwin Hubble first thought it to be in the Local Group, but it was later determined not to be a member.

<span class="mw-page-title-main">Location of Earth</span> Knowledge of the location of Earth

Knowledge of the location of Earth has been shaped by 400 years of telescopic observations, and has expanded radically since the start of the 20th century. Initially, Earth was believed to be the center of the Universe, which consisted only of those planets visible with the naked eye and an outlying sphere of fixed stars. After the acceptance of the heliocentric model in the 17th century, observations by William Herschel and others showed that the Sun lay within a vast, disc-shaped galaxy of stars. By the 20th century, observations of spiral nebulae revealed that the Milky Way galaxy was one of billions in an expanding universe, grouped into clusters and superclusters. By the end of the 20th century, the overall structure of the visible universe was becoming clearer, with superclusters forming into a vast web of filaments and voids. Superclusters, filaments and voids are the largest coherent structures in the Universe that we can observe. At still larger scales the Universe becomes homogeneous, meaning that all its parts have on average the same density, composition and structure.

<span class="mw-page-title-main">Galaxy filament</span> Largest structures in the universe, made of galaxies

In cosmology, galaxy filaments are the largest known structures in the universe, consisting of walls of galactic superclusters. These massive, thread-like formations can commonly reach 50/h to 80/h Megaparsecs —with the largest found to date being the Hercules-Corona Borealis Great Wall at around 3 gigaparsecs (9.8 Gly) in length—and form the boundaries between voids. Due to the accelerating expansion of the universe, the individual clusters of gravitationally bound galaxies that make up galaxy filaments are moving away from each other at an accelerated rate; in the far future they will dissolve.

<span class="mw-page-title-main">Stellar kinematics</span> Study of the movement of stars

In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space.

<span class="mw-page-title-main">Hubble bubble (astronomy)</span> Variation in the Hubble constant

In astronomy, a Hubble bubble would be "a departure of the local value of the Hubble constant from its globally averaged value," or, more technically, "a local monopole in the peculiar velocity field, perhaps caused by a local void in the mass density."

<span class="mw-page-title-main">Local Sheet</span> Nearby extragalactic region of space

The Local Sheet in astronomy is a nearby extragalactic region of space where the Milky Way, the members of the Local Group and other galaxies share a similar peculiar velocity. This region lies within a radius of about 7 Mpc (23 Mly), 0.46 Mpc (1.5 Mly) thick, and galaxies beyond that distance show markedly different velocities. The Local Group has only a relatively small peculiar velocity of 66 km⋅s−1 with respect to the Local Sheet. Typical velocity dispersion of galaxies is only 40 km⋅s−1 in the radial direction. Nearly all nearby bright galaxies belong to the Local Sheet. The Local Sheet is part of the Local Volume and is in the Virgo Supercluster. The Local Sheet forms a wall of galaxies delineating one boundary of the Local Void.

<span class="mw-page-title-main">Laniakea Supercluster</span> Galaxy supercluster that is home to the Milky Way Galaxy and many more galaxies

The Laniakea Supercluster is the galaxy supercluster that is home to the Milky Way and approximately 100,000 other nearby galaxies.

<span class="mw-page-title-main">Dipole repeller</span> Center of effective repulsion in the large-scale flow of galaxies near the Milky Way

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. It is thought to represent a large supervoid, the Dipole Repeller Void.

The KBC Void is an immense, comparatively empty region of space, named after astronomers Ryan Keenan, Amy Barger, and Lennox Cowie, who studied it in 2013. The existence of a local underdensity has been the subject of many pieces of literature and research articles.

<span class="mw-page-title-main">Southern Supercluster</span> Closest neighboring galaxy supercluster

The Southern Supercluster is a nearby supercluster located around 19.5 Mpc (63.6 Mly) in the constellations of Cetus, Fornax, Eridanus, Horologium, and Dorado. It was first identified in 1953 by Gérard de Vaucouleurs.

The Telescopium−Grus Cloud is a galaxy filament in the constellations of Pavo, Indus, and Telescopium. It was first defined by astronomer Brent Tully in his book The Nearby Galaxies Atlas and its companion book The Nearby Galaxies Catalog.

<span class="mw-page-title-main">Local Volume</span>

The Local Volume is a collection of more than 500 galaxies located in an area of the observable universe near us, within a spherical region with a radius of 11 megaparsecs from Earth or up to a radial velocity of redshift of z < 0.002.

References

  1. 1 2 3 "NAME Local Void". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 21 December 2014.
  2. ↑ Nakanishi, Kouichiro; et al. (1 October 1997). "Search and Redshift Survey for IRAS Galaxies behind the Milky Way and Structure of the Local Void". The Astrophysical Journal Supplement Series . 112 (2): 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". New Scientist . Archived from the original on 26 August 2018. Retrieved 13 October 2008.
  4. 1 2 3 4 5 Tully, R. Brent; et al. (20 March 2008). "Our Peculiar Motion Away from the Local Void". The Astrophysical Journal . 676 (1): 184–205. arXiv: 0705.4139 . Bibcode:2008ApJ...676..184T. doi: 10.1086/527428 .
  5. ↑ Tully, R. Brent; Fisher, J. Richard (1987). Nearby Galaxy Atlas. Cambridge University Press. Bibcode:1987nga..book.....T.
  6. 1 2 "Milky Way moving away from void". Astronomy . 12 June 2007. Archived from the original on 8 June 2011. Retrieved 13 October 2008.
  7. 1 2 Whitbourn, Joe R.; Shanks, Tom (June 2016). "The galaxy luminosity function and the Local Hole". Monthly Notices of the Royal Astronomical Society . 459 (1): 496. arXiv: 1603.02322 . Bibcode:2016MNRAS.459..496W. doi: 10.1093/mnras/stw555 .
  8. 1 2 Keenan, Ryan C.; Barger, Amy J.; Cowie, Lennox L. (5 September 2013). "Evidence for a ~300 Mpc Scale Under-density in the Local Galaxy Distribution". The Astrophysical Journal . 775 (1): 62. arXiv: 1304.2884 . Bibcode:2013ApJ...775...62K. doi: 10.1088/0004-637X/775/1/62 .
  9. ↑ Peebles, P. J. E.; Nusser, Adi (June 2010). "Nearby galaxies as pointers to a better theory of cosmic evolution". Nature . 465 (7298): 565–569. arXiv: 1001.1484 . Bibcode:2010Natur.465..565P. doi:10.1038/nature09101. PMID   20520705. S2CID   43767061.
  10. 1 2 Iwata, Ikuru; Ohta, Kouji; Nakanishi, Kouichiro; Chamaraux, Pierre; Roman, Adel T. (2005). The Growth of the Local Void and the Origin of the Local Velocity Anomaly (PDF). Nearby Large-Scale Structures and the Zone of Avoidance. Astronomical Society of the Pacific Conference Series. Vol. 329. pp. 59–66. Archived from the original (PDF) on 13 May 2020. Retrieved 13 May 2020.
  11. ↑ Tully, Brent. "Our CMB Motion: The Local Void influence". Institute for Astronomy. Archived from the original on 28 September 2019. Retrieved 13 October 2008.
  12. ↑ Moss, Adam; Zibin, James P.; Scott, Douglas (15 May 2011). "Precision Cosmology Defeats Void Models for Acceleration". Physical Review D . 83 (10): 103515. arXiv: 1007.3725 . Bibcode:2011PhRvD..83j3515M. doi:10.1103/PhysRevD.83.103515. S2CID   119261120.
  13. ↑ Siegel, Ethan (7 June 2017). "We're Way Below Average! Astronomers Say Milky Way Resides in a Great Cosmic Void". Forbes . Archived from the original on 13 May 2020. Retrieved 9 June 2017.
  14. ↑ "Hubble Sees Two Dwarf Galaxies in Pisces". Sci-News. 15 August 2016. Archived from the original on 3 April 2019.
  15. ↑ Tully, R. Brent. "The Local Void" (PDF). Institute for Astronomy. Archived from the original (PDF) on 18 June 2018. Retrieved 1 May 2018.
  16. ↑ Materne, J. (April 1979). "The structure of nearby groups of galaxies – Quantitative membership probabilities". Astronomy and Astrophysics. 74 (2): 235–243. Bibcode:1979A&A....74..235M.
  17. ↑ Jenner, Lynn, ed. (10 June 2015). "Lonely Galaxy Lost in Space". NASA. Archived from the original on 17 June 2019.
  18. ↑ Lelli, Federico; Verheijen, Marc; Fraternali, Filippo (2014). "The triggering of starbursts in low-mass galaxies". Monthly Notices of the Royal Astronomical Society. 445 (2): 1694–1712. arXiv: 1409.1239 . Bibcode:2014MNRAS.445.1694L. doi:10.1093/mnras/stu1804.
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