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词条 Local Void
释义

  1. Location and dimensions

  2. Effect on surrounds

  3. List of void galaxies

  4. References

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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 also appears to have significantly fewer galaxies than expected from standard cosmology.[9]

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][14]

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 {{convert|60|Mpc|lk=in}}, beginning at the edge of the Local Group.[10] It is believed that the distance from Earth to the centre of the Local Void must be at least {{convert|23|Mpc}}.[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.[11]

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, although this name has not been taken up in other publications.[12]

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.[13] 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 {{convert|600000|mph|km/s|disp=flip}}.[3][6]

List of void galaxies

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

{{expand list|date=August 2016}}
Galaxy Filament Notes Comments
Pisces A [14]
Pisces B [14]
NGC 7077 [15]

References

1. ^1 2 {{cite simbad |title= NAME Local Void |accessdate= 21 December 2014 }}
2. ^{{cite journal |author1=Nakanishi, Kouichiro |author2=Takata, Tadafumi |author3=Yamada, Toru |author4=Takeuchi, Tsutomu T. |author5=Shiroya, Ryuichi |author6=Miyazawa, Morio |author7=Watanabe, Shigeo |author8=Saito, Mamoru |date= 1997 |url= http://www.iop.org/EJ/article/0067-0049/112/2/245/35514.pdf?request-id=ac623b35-5b3d-4c0d-947f-4778e8b92bef |title= Search and Redshift Survey for IRAS Galaxies behind the Milky Way and Structure of the Local Void |journal= Astrophysical Journal Supplement |volume= 112 |issue=2 |page= 245 |bibcode= 1997ApJS..112..245N |doi= 10.1086/313039 }}
3. ^1 2 3 4 {{cite web|url=https://www.newscientist.com/article/dn11971-dwarfflinging-void-is-larger-than-thought.html|title=Dwarf-flinging void is larger than thought|last=Shiga|first=David|date=1 June 2007 |publisher=NewScientist.com news service|accessdate=2008-10-13}}
4. ^1 2 3 4 {{Cite journal | last1 = Tully | first1 = R. B. | last2 = Shaya | first2 = E. J. | last3 = Karachentsev | first3 = I. D. | last4 = Courtois | first4 = H. M.| last5 = Kocevski | first5 = D. D. | last6 = Rizzi | first6 = L. | last7 = Peel | first7 = A. | title = Our Peculiar Motion Away from the Local Void | journal = The Astrophysical Journal | volume = 676 | pages = 184–205 | year = 2008 | doi = 10.1086/527428 | bibcode=2008ApJ...676..184T|arxiv = 0705.4139 }}
5. ^{{cite book | last1 = Tully | first1 = R. Brent | last2 = Fisher | first2 = J. Richard | title = Nearby Galaxy Atlas | publisher = Cambridge University Press | url = http://ned.ipac.caltech.edu/level5/March04/Virgo_cluster/frames.html | date = 1987}}
6. ^1 {{cite web|url=http://www.astronomy.com/asy/default.aspx?c=a&id=5669|title=Milky Way moving away from void|last=Univ. of Hawaii Institute for Astronomy|date=12 June 2007 |publisher=astronomy.com|accessdate=2008-10-13}}
7. ^1 {{cite journal|doi=10.1093/mnras/stw555|title=The galaxy luminosity function and the Local Hole|journal=Monthly Notices of the Royal Astronomical Society|volume=459|pages=496|year=2016|last1=Whitbourn|first1=J. R.|last2=Shanks|first2=T.|arxiv = 1603.02322 |bibcode = 2016MNRAS.459..496W }}
8. ^1 {{Cite journal | last1 = Keenan | first1 = Ryan C. | last2 = Barger | first2 = Amy J. | last3 = Cowie | first3 = Lennox L. | title = Evidence for a ~300 Mpc Scale Under-density in the Local Galaxy Distribution | journal = The Astrophysical Journal | volume = 775 | pages = 62 | year = 2013 | doi = 10.1088/0004-637X/775/1/62 |arxiv = 1304.2884 |bibcode = 2013ApJ...775...62K }}
9. ^{{Cite journal | last1 = Peebles | first1 = P. J. E. | last2 = Nusser | first2 = A. | title = Nearby galaxies as pointers to a better theory of cosmic evolution | journal = Nature | volume = 465 | issue = 7298 | pages = 565–569 | year = 2010 | pmid = 20520705 | doi = 10.1038/nature09101|bibcode = 2010Natur.465..565P |arxiv = 1001.1484 }}
10. ^{{cite web|url=http://www.astro.rug.nl/~weygaert/tim1publication/knawvoid/voidknaw.tully.ppt|title=Our CMB Motion: The Local Void influence|last=Tully|first=Brent|publisher=University of Hawaii, Institute for Astronomy |accessdate=2008-10-13}}
11. ^{{cite journal|last=Moss|first=Adam|author2=James P Zibin |author3=Douglas Scott |title=Precision Cosmology Defeats Void Models for Acceleration|doi=10.1103/PhysRevD.83.103515|date=2011|journal=Physical Review D|volume=83|issue=10|pages=103515|arxiv=1007.3725|bibcode = 2011PhRvD..83j3515M }}
12. ^{{cite web|url=https://www.forbes.com/sites/startswithabang/2017/06/07/were-way-below-average-astronomers-say-milky-way-resides-in-a-great-cosmic-void/#4d53c7cd6d05|title=We're Way Below Average! Astronomers Say Milky Way Resides In A Great Cosmic Void|last=Siegel|first=Ethan|publisher=Forbes|accessdate=2017-06-09}}
13. ^1 {{cite book|last=I|first=Iwata|author2=Ohta, K. |author3=Nakanishi, K. |author4=Chamaraux, P. |author5= Roman, A.T. |title=The Growth of the Local Void and the Origin of the Local Velocity Anomaly|publisher=Astronomical Society of the Pacific|edition=329|volume=Nearby Large-Scale Structures and the Zone of Avoidance |pages=59|url=http://www.aspbooks.org/a/volumes/article_details/?paper_id=1483}}
14. ^1 {{cite news |url= http://www.sci-news.com/astronomy/hubble-dwarf-galaxies-pisces-04103.html |title= Hubble Sees Two Dwarf Galaxies in Pisces |publisher= Sci-News |date= 15 August 2016 }}
15. ^{{Cite web|url=http://amiga.iaa.es/FCKeditor/UserFiles/File/cig09/Tully.pdf|title=The Local Void|last=Tully|first=Brent|date=|website=|archive-url=|archive-date=|dead-url=|access-date=}}

3 : Voids (astronomy)|Interstellar media|Astrochemistry
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