Plaza de España, Seville and Supermassive black hole: Difference between pages

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{{otheruses}}
{{for|other places named Plaza de España|Plaza de España}}
[[Image:rxj1242 comp.jpg|thumb||280px|Top: artist's conception of a supermassive black hole tearing apart a star. Bottom: images believed to show a supermassive black hole devouring a star in galaxy RXJ 1242-11. Left: X-ray image, Right: optical image.<ref>[http://chandra.harvard.edu/photo/2004/rxj1242/ Chandra :: Photo Album :: RX J1242-11 :: 18 Feb 04<!-- Bot generated title -->]</ref>]]
[[Image:SevillaExpo29.jpg||thumb|left|200px|1929 Exposition Building, the Plaza de España]]


A '''supermassive black hole''' is a [[black hole]] with a [[mass]] of an order of magnitude between 10<sup>5</sup> and 1.8x 10<sup>10</sup> solar masses. Most if not all [[galaxy|galaxies]], including the [[Milky Way]]<ref>"Seeing a Star Orbit around the Supermassive Black Hole at the centre of the Milky Way", R. Schödel, et al., Nature, Vol 419, pp. 694-696, October 16, 2002</ref>, are believed to contain supermassive black holes at their centers.<ref>{{Cite journal
The '''Plaza de España''' is one of [[Seville]]'s most easily recognised buildings and the epitome of the [[Moorish Revival]] in Spanish [[architecture]]. In 1929 Seville hosted the [[Spanish-American Exhibition]] and numerous buildings were constructed for the exhibition in Maria Luisa Park, among them the Plaza designed by [[Aníbal González]]. On the Park's edge was built the current Plaza de España to showcase Spain's industry and technology exhibits.
| volume = 31
| issue = 1
| pages = 473–521
| last = Antonucci
| first = R.
| title = Unified Models for Active Galactic Nuclei and Quasars
| journal = Annual Reviews in Astronomy and Astrophysics
| date = 1993
| doi = 10.1146/annurev.aa.31.090193.002353
}}</ref><ref>{{Cite journal
| volume = 107
| pages = 803–845
| last = Urry
| first = P.
| coauthors = Paolo Padovani
| title = Unified schemes for radio–loud AGN
| journal = Publications of the Astronomical Society of the Pacific
| date = 1995
| doi = 10.1086/133630
}}</ref>


Supermassive black holes have properties which distinguish them from their relatively low-mass cousins:
[[Image:PlazaofSpain.JPG|thumb|One of the tiled alcoves on the walls of the Plaza]]
*The average [[density]] of a supermassive black hole (measured as the mass of the black hole divided by its Schwarzschild volume) can be very low, and may actually be lower than the density of [[air]]. This is because the [[Schwarzschild radius]] is [[proportionality (mathematics)|directly proportional]] to [[mass]], while density is inversely proportional to the volume. Since the volume of a spherical object (such as the event horizon of a non-rotating black hole) is directly proportional to the cube of the radius, and mass merely increases linearly, the volume increases at a greater rate than mass. Thus, density decreases for increasingly larger radii of black holes. One should be aware however that this phenomenon results from scientific definitions and does not necessarily manifest itself as a real physical property.
*The [[tidal force]]s in the vicinity of the [[event horizon]] are significantly weaker. Since the central [[gravitational singularity|singularity]] is so far away from the horizon, a hypothetical astronaut travelling towards the black hole center would not experience [[spaghettification|significant tidal force]] until very deep into the black hole.


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The Plaza is a huge half-circle of guda cheese with buildings continually running around the edge accessible over the moat by numerous beautiful bridges . In the centre is a large fountain. Today the plaza mainly consists of Government buildings, but the beauty remains. A popular way to view the exhibition is by renting out a rowing boat and drifting around the moat. By the walls of the Plaza are many tiled alcoves, each representing a different province of Spain. Tourists can have their photo taken by their own home province.
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[[Image:PlazaDeEspanaFountain.jpg|thumb|left|150px|The large fountain in the centre of the Plaza de España]]
<!-- Commented out because image was deleted: [[Image:PlazaDeEspana.jpg|thumb|right|200px|A beautiful bridge over the moat|{{deletable image-caption|1=Sunday, 23 March 2008}}]] -->


==In Fiction==
==Doppler measurements==
Direct [[Doppler effect|Doppler]] measures of water [[Astrophysical maser|masers]] surrounding the [[Active galactic nucleus|nucleus]] of nearby galaxies have revealed a very fast [[keplerian]] motion, only possible with a high concentration of matter in the center. Currently, the only known objects that can pack enough matter in such a small space are black holes, or things that will evolve into black holes within astrophysically short timescales. For [[active galaxy|active galaxies]] farther away, the width of broad spectral lines can be used to probe the gas orbiting near the event horizon. The technique of [[reverberation mapping]] uses variability of these lines to measure the mass, and perhaps the spin of the black hole that powers the active galaxy's "engine".
*Plaza de España is used as the "Cairo Great Britain Army Headquarters" for the movie [[Lawrence of Arabia (film)]]
*It was also used as a setting for [[Naboo]] in ''[[Star Wars Episode II: Attack of the Clones]]'', though it was digitally modified.
*In [[Dan Brown]]'s novel ''[[Digital Fortress]]'', the first scene takes place in the Plaza.


Such supermassive black holes in the center of many galaxies are thought to be the "engine" of [[active galaxy|active objects]] such as [[Seyfert galaxy|Seyfert galaxies]] and [[quasar]]s. The [[Max Planck Institute for Extraterrestrial Physics]] and [[UCLA]] Galactic Center Group<ref>[http://www.astro.ucla.edu/~ghezgroup/gc/ UCLA Galactic Center Group<!-- Bot generated title -->]</ref> provided evidence that [[Sagittarius A*]] is the supermassive black hole residing at the center of the [[Milky Way]] based on data from the [[ESO]]<ref>[http://www.eso.org/outreach/press-rel/pr-2002/pr-17-02.html ESO - 2002<!-- Bot generated title -->]</ref> and the [[Keck telescope]]s.<ref>http://www.keckobservatory.org/news/old_pages/andreaghez.html</ref> Our galactic central black hole is calculated to have a mass of approximately 4.1 million solar masses.<ref>http://www.skyandtelescope.com/news/27621359.html</ref>
[[Image:EspanaNight.jpg|thumb|right|200px|The Plaza at night]]


==Supermassive black holes outside the Milky Way==
== External links ==
There are a handful of galaxies aside from the Milky Way in which the presence of a supermassive black hole can unambiguously be inferred from the motion of stars or gas near the center. These include two other galaxies in the [[Local Group]], [[Messier 31]] and [[Messier 32]]. In a larger number of so-called [[active galaxies]] and [[quasars]], the presence of a supermassive black hole is implied by the "activity" of the nucleus, i.e. by the emission of large amounts of radiation, presumably from gas that is spiralling in to the black hole.
*[http://homepage.ntlworld.com/keir.clarke/espana.htm View on Google Maps] Includes a short video of the plaza.
It is currently believed that the majority of bright galaxies contain a supermassive black hole but that most are in an "inactive" state not accreting much matter. Currently, there is no compelling evidence for massive black holes at the centers of [[globular cluster]]s, [[dwarf galaxies]], or smaller stellar systems.
*[http://plaza-espana.netfirms.com/the-plaza-de-espana-in-seville.htm Free pics of Plaza de España and a short description]


At least one galaxy, [[Galaxy 0402+379]] , appears to have two supermassive black holes at its center, forming a binary system. Should these collide, the event would create strong [[gravitational waves]]. Binary supermassive black holes are believed to be a common consequence of galaxy mergers <ref>D. Merritt and M. Milosavljevic (2005). "Massive Black Hole Binary Evolution."
{{commonscat|Plaza de España (Sevilla)}}
http://relativity.livingreviews.org/Articles/lrr-2005-8/</ref>.


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{{coord|37|22|38|N|5|59|13|W|type:landmark|display=title}}


[[Category:Seville]]
[[Category:Moorish revival architecture]]
[[Category:Star Wars filming locations]]


==References==
[[de:Plaza de España (Sevilla)]]
<references/>
[[es:Plaza de España (Sevilla)]]
* {{cite book
[[fr:Plaza de España (Séville)]]
| author=Julian H. Krolik
[[it:Piazza di Spagna (Siviglia)]]
| title=Active Galactic Nuclei
[[nl:Plaza de España (Sevilla)]]
| publisher=Princeton University Press
[[ja:スペイン広場 (セビリア)]]
| year=1999
| id =ISBN 0-691-01151-6}}

== External links ==
*[http://www.hubblesite.org/go/blackholes Black Holes: Gravity's Relentless Pull] Award-winning interactive multimedia Web site about the physics and astronomy of black holes from the Space Telescope Science Institute
* [http://chandra.harvard.edu/photo/2002/0157/0157_composite.jpg Images of supermassive black holes]
* [http://antwrp.gsfc.nasa.gov/apod/image/0210/mwcentre_eso_big.jpg NASA images of supermassive black holes]
* [http://arxiv.org/abs/0808.2624 Is there a Supermassive Black Hole at the Center of the Milky Way? (arxiv preprint)]
* [http://www.einstein-online.info/en/spotlights/milkyway_bh/index.html The black hole at the heart of the Milky Way]
* [http://www.eso.org/outreach/press-rel/pr-2002/video/vid-02-02.mpg ESO video clip of orbiting star] (533 KB MPEG Video)
* [http://www.eso.org/outreach/press-rel/pr-2002/pr-17-02.html Star Orbiting Massive Milky Way Centre Approaches to within 17 Light-Hours] [[ESO]], [[October 21]], [[2002]]
* [http://www.universetoday.com/am/publish/early_black_holes_grew_quickly.html Early Black Holes Grew Up Quickly]
* [http://www.astro.ucla.edu/research/galcenter/ Images, Animations, and New Results from the UCLA Galactic Center Group]
* [http://www.washingtonpost.com/wp-dyn/content/article/2007/10/30/AR2007103002073.html?nav=most_emailed Washington Post article on Supermassive black holes]
*[http://www.orbitsimulator.com/gravity/articles/mwblackhole.html A simulation of the stars orbiting the Milky Way's central massive black hole]
{{black holes}}

[[Category:Black holes]]
[[Category:Galaxies]]
[[Category:Supermassive black holes]]

[[ca:Forat negre supermassiu]]
[[cs:Supermasivní černá díra]]
[[es:Agujero negro supermasivo]]
[[eo:Pezega nigra truo]]
[[fa:سیاه‌چاله کلان‌جرم]]
[[fr:Trou noir supermassif]]
[[ko:초대질량블랙홀]]
[[it:Buco nero supermassiccio]]
[[he:חור שחור על-מסיבי]]
[[hu:Szupermasszív fekete lyuk]]
[[no:Supermassivt sort hull]]
[[pl:Supermasywna czarna dziura]]
[[sk:Supermasívna čierna diera]]
[[sl:Supermasivna črna luknja]]
[[fi:Supermassiivinen musta aukko]]
[[sv:Supermassiva svarta hål]]
[[th:หลุมดำมวลยวดยิ่ง]]
[[zh:超重黑洞]]

Revision as of 20:58, 10 October 2008

For other uses, see Supermassive black hole (disambiguation).
Top: artist's conception of a supermassive black hole tearing apart a star. Bottom: images believed to show a supermassive black hole devouring a star in galaxy RXJ 1242-11. Left: X-ray image, Right: optical image.[1]

A supermassive black hole is a black hole with a mass of an order of magnitude between 105 and 1.8x 1010 solar masses. Most if not all galaxies, including the Milky Way[2], are believed to contain supermassive black holes at their centers.[3][4]

Supermassive black holes have properties which distinguish them from their relatively low-mass cousins:

  • The average density of a supermassive black hole (measured as the mass of the black hole divided by its Schwarzschild volume) can be very low, and may actually be lower than the density of air. This is because the Schwarzschild radius is directly proportional to mass, while density is inversely proportional to the volume. Since the volume of a spherical object (such as the event horizon of a non-rotating black hole) is directly proportional to the cube of the radius, and mass merely increases linearly, the volume increases at a greater rate than mass. Thus, density decreases for increasingly larger radii of black holes. One should be aware however that this phenomenon results from scientific definitions and does not necessarily manifest itself as a real physical property.
  • The tidal forces in the vicinity of the event horizon are significantly weaker. Since the central singularity is so far away from the horizon, a hypothetical astronaut travelling towards the black hole center would not experience significant tidal force until very deep into the black hole.

blubblubblbub

Doppler measurements

Direct Doppler measures of water masers surrounding the nucleus of nearby galaxies have revealed a very fast keplerian motion, only possible with a high concentration of matter in the center. Currently, the only known objects that can pack enough matter in such a small space are black holes, or things that will evolve into black holes within astrophysically short timescales. For active galaxies farther away, the width of broad spectral lines can be used to probe the gas orbiting near the event horizon. The technique of reverberation mapping uses variability of these lines to measure the mass, and perhaps the spin of the black hole that powers the active galaxy's "engine".

Such supermassive black holes in the center of many galaxies are thought to be the "engine" of active objects such as Seyfert galaxies and quasars. The Max Planck Institute for Extraterrestrial Physics and UCLA Galactic Center Group[5] provided evidence that Sagittarius A* is the supermassive black hole residing at the center of the Milky Way based on data from the ESO[6] and the Keck telescopes.[7] Our galactic central black hole is calculated to have a mass of approximately 4.1 million solar masses.[8]

Supermassive black holes outside the Milky Way

There are a handful of galaxies aside from the Milky Way in which the presence of a supermassive black hole can unambiguously be inferred from the motion of stars or gas near the center. These include two other galaxies in the Local Group, Messier 31 and Messier 32. In a larger number of so-called active galaxies and quasars, the presence of a supermassive black hole is implied by the "activity" of the nucleus, i.e. by the emission of large amounts of radiation, presumably from gas that is spiralling in to the black hole. It is currently believed that the majority of bright galaxies contain a supermassive black hole but that most are in an "inactive" state not accreting much matter. Currently, there is no compelling evidence for massive black holes at the centers of globular clusters, dwarf galaxies, or smaller stellar systems.

At least one galaxy, Galaxy 0402+379 , appears to have two supermassive black holes at its center, forming a binary system. Should these collide, the event would create strong gravitational waves. Binary supermassive black holes are believed to be a common consequence of galaxy mergers [9].

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References

  1. ^ Chandra :: Photo Album :: RX J1242-11 :: 18 Feb 04
  2. ^ "Seeing a Star Orbit around the Supermassive Black Hole at the centre of the Milky Way", R. Schödel, et al., Nature, Vol 419, pp. 694-696, October 16, 2002
  3. ^ Antonucci, R. (1993). "Unified Models for Active Galactic Nuclei and Quasars". Annual Reviews in Astronomy and Astrophysics. 31 (1): 473–521. doi:10.1146/annurev.aa.31.090193.002353.
  4. ^ Urry, P. (1995). "Unified schemes for radio–loud AGN". Publications of the Astronomical Society of the Pacific. 107: 803–845. doi:10.1086/133630. {{cite journal}}: C1 control character in |title= at position 26 (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  5. ^ UCLA Galactic Center Group
  6. ^ ESO - 2002
  7. ^ http://www.keckobservatory.org/news/old_pages/andreaghez.html
  8. ^ http://www.skyandtelescope.com/news/27621359.html
  9. ^ D. Merritt and M. Milosavljevic (2005). "Massive Black Hole Binary Evolution." http://relativity.livingreviews.org/Articles/lrr-2005-8/
  • Julian H. Krolik (1999). Active Galactic Nuclei. Princeton University Press. ISBN 0-691-01151-6.

External links

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