Open main menu
Home
Random
Recent changes
Special pages
Community portal
Preferences
About Wikipedia
Disclaimers
Incubator escapee wiki
Search
User menu
Talk
Dark mode
Contributions
Create account
Log in
Editing
Great Attractor
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
{{Short description|Region of overdensity of galaxies within the local supercluster}} [[Image:2MASS LSS chart-NEW Nasa.jpg|right|thumb|upright=2.6|Panoramic view of the entire near-infrared sky. The location of the Great Attractor is shown following the long blue arrow at bottom right.]] [[File:Gran Atractor.jpg|thumb|upright=1.4|[[Hubble Space Telescope]] image showing part of the [[Norma Cluster]], including [[ESO 137-002]]]] The '''Great Attractor''' is a region of gravitational attraction in [[intergalactic space]] and the apparent central gravitational point of the [[Laniakea Supercluster]] of galaxies that includes the [[Milky Way]] galaxy, as well as about 100,000 other galaxies. The observed attraction suggests a localized concentration of mass having the order of 10<sup>16</sup> solar masses.<ref name=BehindMilkyWay/> However, it is obscured by the Milky Way's [[galactic plane]], lying behind the [[Zone of Avoidance]] (ZOA), so that in visible light wavelengths, the Great Attractor is difficult to observe directly.<ref name="UniverseToday2014">{{cite news |url=https://www.universetoday.com/113150/what-is-the-great-attractor/ |title=What is the Great Attractor? |date=2014-07-14 |website=Universe Today |access-date=2018-06-24 |df=dmy-all |language=en-US}}</ref> The attraction is observable by its effect on the motion of galaxies and their associated clusters over a region of hundreds of millions of [[light-year]]s across the [[universe]]. These galaxies are observable above and below the Zone of Avoidance; all are [[redshift]]ed in accordance with the [[Hubble flow]], indicating that they are receding relative to the Milky Way and to each other, but the variations in their redshifts are large enough and regular enough to reveal that they are slightly drawn towards the attraction. The variations in their redshifts are known as [[Peculiar velocity|''peculiar velocities'']], and cover a range from about +700 km/s to −700 km/s, depending on the angular deviation from the direction to the Great Attractor. The Great Attractor itself is moving towards the [[Shapley Supercluster]].<ref name=UniverseToday2014/> == History == The Great Attractor was named by [[Alan Dressler]] in 1987,<ref>{{Cite journal |last=Dressler |first=Alan |date=1987 |title=The Large-Scale Streaming of Galaxies |url=https://www.jstor.org/stable/24979477 |journal=Scientific American |volume=257 |issue=3 |pages=46–55 |doi=10.1038/scientificamerican0987-46 |jstor=24979477 |bibcode=1987SciAm.257c..46D |issn=0036-8733|url-access=subscription }}</ref><ref name=StraussWillick>{{Cite journal |last1=Strauss |first1=Michael A. |last2=Willick |first2=Jeffrey A. |date=1995-10-01 |title=The density and peculiar velocity fields of nearby galaxies |url=https://dx.doi.org/10.1016/0370-1573%2895%2900013-7 |journal=Physics Reports |volume=261 |issue=5 |pages=271–431 |doi=10.1016/0370-1573(95)00013-7 |issn=0370-1573|arxiv=astro-ph/9502079 |bibcode=1995PhR...261..271S }}</ref> following decades of redshift surveys that built up a large dataset of redshift values. The redshift values and distance measurements independent of redshift measurements were then combined to create maps of peculiar velocity.<ref name=StraussWillick/>{{rp|274}} Through a series of peculiar velocity tests, astrophysicists found that the Milky Way was moving in the direction of the [[Centaurus|constellation of Centaurus]] at about 600{{nbs}}km/s. {{cn|date=November 2023}} Then, the discovery of [[cosmic microwave background]] (CMB) dipoles was used to reflect the motion of the [[Local Group]] of galaxies towards the Great Attractor.<ref>{{Cite web |title=Cosmic Microwave Background Dipole {{!}} COSMOS |url=https://astronomy.swin.edu.au/cosmos/c/Cosmic+Microwave+Background+Dipole |access-date=2022-03-14 |website=astronomy.swin.edu.au}}</ref> The 1980s brought many discoveries about the Great Attractor, such as the fact that the Milky Way is not the only galaxy impacted. Approximately 400 [[elliptical galaxies]] are moving toward the Great Attractor beyond the Zone of Avoidance caused by the Milky Way galaxy light. Intense efforts during the late 1990s, to work through the difficulties caused by the occlusion by the Milky Way, identified the [[Norma Cluster]] at the center of the Great Attractor region.<ref name=BehindMilkyWay>{{Cite book |last=Kraan-Korteweg |first=Renée C. |title=Reviews in Modern Astronomy |date=2005-07-22 |editor-last=Röser |editor-first=Siegfried |chapter=Cosmological Structures behind the Milky Way |chapter-url=https://onlinelibrary.wiley.com/doi/10.1002/3527608966.ch3 |language=en |publisher=Wiley |pages=48–75 |doi=10.1002/3527608966.ch3 |arxiv=astro-ph/0502217 |isbn=978-3-527-40608-1}}</ref> ==Location== The first indications of a deviation from uniform expansion of the universe were reported in 1973 and again in 1978. The location of the Great Attractor was finally determined in 1986: It is situated at a distance of somewhere between 150 and 250 Mly (million light-years) (47–79 [[megaparsec|Mpc]]), the larger being the most recent estimate, away from the [[Milky Way]], in the direction of the constellations [[Triangulum Australe]] (The Southern Triangle) and [[Norma (constellation)|Norma]] (The Carpenter's Square).<ref>{{cite web |url=https://www.nasa.gov/mission_pages/hubble/science/great-attractor.html |title=Hubble focuses on "the Great Attractor" |publisher=[[NASA]] |date=2013-01-18 |access-date=2020-10-24 |df=dmy-all}}</ref> While objects in that direction lie in the [[Zone of Avoidance]] (the part of the night sky obscured by the Milky Way galaxy) and are thus difficult to study with visible wavelengths, X-ray observations have revealed that region of space to be dominated by the [[Norma Cluster]] (ACO 3627),<ref>{{cite book |doi=10.1007/3-540-45371-7_8 |chapter=Galaxies behind the Milky Way and the Great Attractor |title=From the Sun to the Great Attractor |volume=556 |pages=301–344 |series=Lecture Notes in Physics |year=2000 |last1=Kraan-Korteweg |first1=Renée C. |publisher=Springer |location=Berlin, Heidelberg |isbn=978-3-540-41064-5 |citeseerx=10.1.1.338.3806|s2cid=14507443 }}</ref><ref>{{cite web |url=http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/990924a2.html |archive-url=https://web.archive.org/web/20030218093933/http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/990924a2.html |archive-date=February 18, 2003 |series=NASA's Ask an Astrophysicist |title=The Great Attractor |first1=Koji |last1=Mukai |first2=Rich |last2=Mushotzky |first3=Maggie |last3=Masetti |df=dmy-all |quote=It is now thought that the Great Attractor is probably a supercluster, with Abell 3627 near its center.}}</ref> a massive cluster of galaxies containing a preponderance of large, old galaxies, many of which are [[galaxy collision|colliding with their neighbours]] and radiating large amounts of [[radio wave]]s. ==Debate over apparent mass== In 1992, much of the apparent signal of the Great Attractor was attributed to a statistical effect called ''[[Malmquist bias]]''.<ref>{{cite Q|Q55968841}}</ref> In 2005, astronomers conducting an X-ray survey of part of the sky known as the ''Clusters in the Zone of Avoidance'' (CIZA) project reported that the Great Attractor was actually only one tenth the mass that scientists had originally estimated. The survey also confirmed earlier theories that the Milky Way galaxy is in fact being pulled toward a much more massive cluster of galaxies near the [[Shapley Supercluster]], which lies beyond the Great Attractor, and which is called the [[Shapley Attractor]].<ref>{{cite press release |url=http://www.ifa.hawaii.edu/info/press-releases/kocevski-1-06/ |title=X-rays reveal what makes the Milky Way move |publisher=Ifa.hawaii.edu |date=2006-01-11 |access-date=2020-10-24 |df=dmy-all}}</ref> == Norma Wall == [[File:Great Attractor and Norma Wall.jpg|thumb|View of the region of the Great Attractor, with Pavo II, Norma, Cen-Crux and the CIZA J1324.7-5736 clusters forming the Norma Wall.]] A massive [[galaxy filament]], called the Norma Wall (also called Great Attractor Wall<ref name=":6">{{Cite journal |last1=Jarrett |first1=T. H. |last2=Koribalski |first2=B. S. |last3=Kraan-Korteweg |first3=R. C. |last4=Woudt |first4=P. A. |last5=Whitney |first5=B. A. |last6=Meade |first6=M. R. |last7=Babler |first7=B. |last8=Churchwell |first8=E. |last9=Benjamin |first9=R. A. |last10=Indebetouw |first10=R. |date=March 2007 |title=Discovery of Two Galaxies Deeply Embedded in the Great Attractor Wall |url=https://iopscience.iop.org/article/10.1086/510668 |journal=The Astronomical Journal |language=en |volume=133 |issue=3 |pages=979–986 |arxiv=astro-ph/0611397 |bibcode=2007AJ....133..979J |doi=10.1086/510668 |issn=0004-6256 |s2cid=5930404}}</ref>) is located at the center of the supposed position of the Great Attractor. The Norma Wall contains the clusters [[Pavo–Indus Supercluster|Pavo II]], [[Norma Cluster|Norma]], [[Centaurus-Crux Cluster|Centaurus-Crux]] and [[CIZA J1324.7−5736]]. The most massive cluster in this region is the Norma supercluster.<ref>{{Cite journal |last1=Woudt |first1=P. A. |last2=Kraan-Korteweg |first2=R. C. |last3=Lucey |first3=J. |last4=Fairall |first4=A. P. |last5=Moore |first5=S. A. W. |date=2008-01-01 |title=The Norma cluster (ACO 3627) - I. A dynamical analysis of the most massive cluster in the Great Attractor |journal=Monthly Notices of the Royal Astronomical Society |volume=383 |issue=2 |pages=445–457 |doi=10.1111/j.1365-2966.2007.12571.x |doi-access=free |issn=0035-8711|arxiv=0706.2227 |bibcode=2008MNRAS.383..445W }}</ref> Later studies found that the wall continues over to the constellations of Centaurus and Vela.<ref name=":6" /> ==Laniakea Supercluster== {{main|Laniakea Supercluster}} The proposed [[Laniakea Supercluster]] is defined as the Great Attractor's basin. It covers approximately four main galaxy superclusters, including superclusters of [[Virgo Supercluster|Virgo]] and [[Hydra–Centaurus Supercluster|Hydra–Centaurus]], and spans across 500 million light years. Because it is not dense enough to be gravitationally bound, it should be dispersing as the universe expands, but it is instead anchored by a gravitational focal point. Thus the Great Attractor would be the core of the new supercluster. The local flows of the Laniakea supercluster converge in the region of the Norma and [[Centaurus Cluster|Centaurus Clusters]], approximately at the position of the Great Attractor.<ref>{{cite Q|Q28314882}}</ref> ==See also== * {{annotated link|CfA2 Great Wall}} * {{annotated link|Dark flow}} * {{annotated link|Dark matter}} * {{annotated link|Dipole repeller}} * {{annotated link|Hercules–Corona Borealis Great Wall}} * {{annotated link|Shapley Supercluster}} * {{annotated link|South Pole Wall}} * {{annotated link|Big Crunch}} ==References== {{Reflist|30em}} ==Further reading== * {{cite book |last=Dressler |first=Alan |title=Voyage to the Great Attractor: Exploring Intergalactic Space |publisher=[[Alfred A. Knopf]] |date=1994 |location=New York, New York |page=355 |isbn=978-0-394-58899-5 |url=https://books.google.com/books?id=TZvvAAAAMAAJ&pg=PA355}} * {{cite Q|Q68868628}} * {{cite Q|Q68831133}} * {{cite Q|Q59093661}} * {{cite journal |bibcode=1988ApJ...334L..59B |title=Searching for the Great Attractor |journal=The Astrophysical Journal |volume=334 |pages=L59 |last1=Bertschinger |first1=Edmund |last2=Juszkiewicz |first2=Roman |year=1988 |doi=10.1086/185312|doi-access=free }} ==External links== * {{cite news |url=https://www.nationalgeographic.com/news/2014/9/140903-galaxy-supercluster-map-laniakea-astronomy-science-ngspace/ |archive-url=https://web.archive.org/web/20200225024043/https://www.nationalgeographic.com/news/2014/9/140903-galaxy-supercluster-map-laniakea-astronomy-science-ngspace/ |url-status=dead |archive-date=February 25, 2020 |title=New map locates Milky Way in neighborhood of 100,000 galaxies |first=Nadia |last=Drake |author-link=Nadia Drake |website=National Geographic |date=3 September 2014}} * {{cite AV media |url=https://vimeo.com/64868713 |title=Cosmography of the Local Universe |website=Vimeo |medium=video}} – video clip showing the Great Attractor {{Portal bar|Astronomy|Stars|Outer space}} {{Authority control}} [[Category:Great Attractor| ]] [[Category:Shapley Supercluster]] [[Category:Virgo Supercluster]] [[Category:Norma Cluster]] [[Category:Large-scale structure of the cosmos]] [[Category:Astronomical objects discovered in 1986]]
Edit summary
(Briefly describe your changes)
By publishing changes, you agree to the
Terms of Use
, and you irrevocably agree to release your contribution under the
CC BY-SA 4.0 License
and the
GFDL
. You agree that a hyperlink or URL is sufficient attribution under the Creative Commons license.
Cancel
Editing help
(opens in new window)
Pages transcluded onto the current version of this page
(
help
)
:
Template:Annotated link
(
edit
)
Template:Authority control
(
edit
)
Template:Cite AV media
(
edit
)
Template:Cite Q
(
edit
)
Template:Cite book
(
edit
)
Template:Cite journal
(
edit
)
Template:Cite news
(
edit
)
Template:Cite press release
(
edit
)
Template:Cite web
(
edit
)
Template:Cn
(
edit
)
Template:Main
(
edit
)
Template:Nbs
(
edit
)
Template:Portal bar
(
edit
)
Template:Reflist
(
edit
)
Template:Rp
(
edit
)
Template:Short description
(
edit
)