ผลต่างระหว่างรุ่นของ "หลุมดำ"
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บรรทัด 316:
การสั่นกึ่งคาบ([[Quasi-periodic oscillations]]) สามารถใช้ระบุมวลของหลุมดำได้<ref>{{cite web|url=http://www.eurekalert.org/pub_releases/2008-04/nsfc-nsi040108.php|title=NASA scientists identify smallest known black hole}}</ref> เทคนิคนี้สามารถใช้ได้กับความสัมพันธ์ระหว่างหลุมดำและภายในวงแหวนรอบ ๆ ตัวมัน ที่มีก๊าซหมุนวนภายในก่อนที่จะถึงขอบฟ้าเหตุการณ์ เมื่อก๊าซยุบตัวลงจะแผ่รังสีเอ็กซ์ด้วยความเข้มที่แตกต่างกันในรูปแบบซ้ำ ๆ ในช่วงเวลาปกติ สัญญาณนี้เรียกว่า ควอไซน์ พิริออดิก ออสซิลเลชั่น หรือ คิวพีโอ ความถี่ คิวพีโอ นี้ขึ้นกับมวลของหลุมดำ ซึ่งจะเกิดที่ขอบฟ้าเหตุการณ์ใกล้ ๆ กับหลุมดำ ดังนั้น คิวพีโอจะมีความถี่มากขึ้น สำหรับหลุมดำที่มีมวลมากกว่านี้ ขอบฟ้าเหตุการณ์ก็จะอยู่ไกลข้น ทำให้ ความถี่คิวพีโอ ลดลง
==หลุมดำที่พบ==
===หลุมดำยักษ์พบที่ใจกลางกาแล็กซี่===
[[Image:M87 jet.jpg|left|thumb|284px|พวยก๊าซที่พุ่งออกจากใจกลางเมซิเออร์ 87 ในรูปนี้มาจากนิวเคลียสที่ยังมีพลังของ[[กาแล็กซี่]]ที่อาจจะมีหลุมดับยักา์อยู่ Credit: [[Hubble Space Telescope]]/[[NASA]]/[[ESA]].]]
จากข้อมูลสมาคมดาราศาสตร์อเมริกา กาแล็กซี่ขนาดใหญ่มักจะมีหลุมดำขนาดใหญ่ที่ใจกลาง โดยที่มวลของหลุมดำจะแปรผันตรงกับกาแล็กซี่ที่มันอยู่ มีการใช้กล้องโทรทรรศน์ฮับเบิลสเปซและกล้องโทรทรรศน์ภาพพื้นใน[[ฮาวาย]]ในการสำรวจกาแล็กซี่ขนาดใหญ่
ใช้เวลาเป็นทศวรรษ นักศาสตร์ใช้คำว่ากาแล๊กซี่ที่มีพลังในการอธิบายลักษณะที่แตกต่าง เช่น เส้นสเปกตรัมที่ต่างไปคือมีการแผ่พลังงาน และการแผ่พลังงานที่รุนแรง <ref name="krolik1999">{{cite book
| author=J. H. Krolik
| year=1999
| title=Active Galactic Nuclei
| publisher=Princeton University Press
| location=Princeton, New Jersey
| id=ISBN 0-691-01151-6}}</ref><ref name="sparkegallagher2000">{{cite book
| author=L. S. Sparke, J. S. Gallagher III
| year=2000
| title=Galaxies in the Universe: An Introduction
| publisher=Cambridge University Press
| location=Cambridge
| id=ISBN 0-521-59704-4}}</ref>
อย่างไรก็ตาม ในทางทฤษฎีและการสังเกตการณ์แสดงให้เห็นว่าในนิวเคลียสของกาแล็กซี่ที่มีพลัง หรือ เอจีเอ็น ([[Active galactic nucleus|active galactic nuclei]]) นั้นน่าจะมีหลุมดำยักษ์อยู่<ref name="krolik1999"/><ref name="sparkegallagher2000"/> รูปแบบของเอจีเอ็นนี้ประกอลไปด้วยใจกลางหลุมดำที่อาจจะมีพลังงานมากกว่าดวงอาทิตย์เป็นพันล้านหรือล้านล้านเท่า a disk of [[interstellar gas|gas]] and [[interstellar dust|dust]] called an [[Accretion disc|accretion disk]]; and two [[relativistic jet|jets]] that are perpendicular to the accretion disk.<ref name="sparkegallagher2000"/>
Although supermassive black holes are expected to be found in most AGN, only some galaxies' nuclei have been more carefully studied in attempts to both identify and measure the actual masses of the central supermassive black hole candidates. Some of the most notable galaxies with supermassive black hole candidates include the [[Andromeda Galaxy]], [[Messier 32|M32]], [[Messier 87|M87]], [[NGC 3115]], [[NGC 3377]], [[NGC 4258]], and the [[Sombrero Galaxy]].<ref name="kormendyrichstone1995">{{cite journal
| author=J. Kormendy, D. Richstone
| title=Inward Bound---The Search For Supermassive Black Holes In Galactic Nuclei
| journal=Annual Reviews of Astronomy and Astrophysics
| year=1995
| volume=33
| pages=581–624
| url=http://adsabs.harvard.edu/abs/1995ARA&A..33..581K
| doi=10.1146/annurev.aa.33.090195.003053}}</ref>
Astronomers are confident that our own [[Milky Way]] galaxy has a supermassive black hole at its center, in a region called [[Sagittarius A*]]:
* A star called [[S2 (star)]] follows an [[elliptical]] orbit with a [[orbital period|period]] of 15.2 years and a [[pericenter]] (closest) distance of 17 [[light hour]]s from the central object.
* The first estimates indicated that the central object contains 2.6M (2.6 million) solar masses and has a radius of less than 17 light hours. Only a black hole can contain such a vast mass in such a small volume.
* Further observations<ref>{{cite journal| last = Ghez| first = A. M.| authorlink = Andrea Ghez| coauthors = Salim, S.; Hornstein, S. D.; Tanner, A.; Lu, J. R.; Morris, M.; Becklin, E. E.; Duchêne, G.| title = Stellar Orbits around the Galactic Center Black Hole| journal = The Astrophysical Journal| volume = 620| issue = 2| pages = 744–757| year = 2005| month = May| url = http://www.journals.uchicago.edu/doi/abs/10.1086/427175| accessdate = 2008-05-10| doi = 10.1086/427175}}</ref> strengthened the case for a black hole, by showing that the central object's mass is about 3.7M solar masses and its radius no more than 6.25 light-hours.
===Intermediate-mass black holes in globular clusters===
In 2002, the Hubble Space Telescope produced observations indicating that [[globular clusters]] named [[Messier 15|M15]] and [[Mayall II|G1]] may contain [[intermediate-mass black hole]]s.<ref>{{cite journal |author=Gerssen, Joris |coauthors=van der Marel, Roeland P.; Gebhardt, Karl; Guhathakurta, Puragra; Peterson, Ruth C.; Pryor, Carlton |year=2002 |month=December |title=Hubble Space Telescope Evidence for an Intermediate-Mass Black Hole in the Globular Cluster M15. II. Kinematic Analysis and Dynamical Modeling |journal=The Astronomical Journal |volume=124 |issue=6 |pages= 3270–3288 |url=http://arxiv.org/abs/astro-ph/0209315 | doi = 10.1086/344584}}</ref><ref>{{cite web|url=http://hubblesite.org/newscenter/archive/releases/cosmology/2002/18/text/|title=Hubble Discovers Black Holes in Unexpected Places|work=HubbelSite |accessdate=2007-10-31|date=2002-09-17}}</ref> This interpretation is based on the sizes and periods of the orbits of the stars in the globular clusters. But the Hubble evidence is not conclusive, since a group of [[neutron star]]s could cause similar observations. Until recent discoveries, many astronomers thought that the complex gravitational interactions in globular clusters would eject newly-formed black holes.
In November 2004 a team of astronomers reported the discovery of the first well-confirmed [[intermediate-mass black hole]] in our Galaxy, orbiting three light-years from Sagittarius A*. This black hole of 1,300 solar masses is within a cluster of seven stars, possibly the remnant of a massive star cluster that has been stripped down by the Galactic Centre.<ref name = "Nature.com-20060325">{{cite web| url=http://www.nature.com/news/2004/041108//full/041108-2.html#B2| title=Second black hole found at the centre of our Galaxy| work=NatureNews |accessdate=2006-03-25 |doi=10.1038/news041108-2}}</ref><ref name = "edpsciences-usa.org-2004">{{citation |first1=J.P. |last1=Maillard |first2=T. |last2=Paumard |first3=S.R. |last3=Stolovy |first4=F. |last4=Rigaut |title=The nature of the Galactic Center source IRS 13 revealed by high spatial resolution in the infrared |journal=Astron.Astrophys. |volume=423 |year=2004 |pages=155–167 |url=http://arxiv.org/abs/astro-ph/0404450 |doi=10.1051/0004-6361:20034147}}</ref> This observation may add support to the idea that supermassive black holes grow by absorbing nearby smaller black holes and stars.
In January 2007, researchers at the University of Southampton in the United Kingdom reported finding a black hole, possibly of about 10 solar masses, in a globular cluster associated with a galaxy named NGC 4472, some 55 million light-years away.<ref>http://xxx.lanl.gov/abs/0805.2952</ref><ref>{{citation |first1=Thomas J. |last1=Maccarone |first2=Arunav |last2=Kundu |first3=Stephen E. |last3=Zepf |first4=Katherine L. |last4=Rhode |title= A black hole in a globular cluster |journal=Nature |volume=445 |year=2007 |pages=183–185 |url=http://arxiv.org/abs/astro-ph/0701310 |doi= 10.1038/nature05434}}</ref>
===Stellar-mass black holes in the Milky Way===
[[Image:Accretion disk.jpg|right|325px|thumb|Artist's impression of a binary system consisting of a black hole and a [[main sequence]] star. The black hole is drawing matter from the main sequence star via an [[Accretion disc|accretion disk]] around it, and some of this matter forms a [[galactic jet|gas jet]].]]
Our Milky Way galaxy contains several probable [[stellar-mass black hole]]s which are closer to us than the supermassive black hole in the [[Sagittarius A*]] region. These candidates are all members of [[X-ray binary]] systems in which the denser object draws matter from its partner via an accretion disk. The probable black holes in these pairs range from three to more than a dozen [[solar mass]]es.<ref name = "Casares-Holes">{{Cite conference |first=J. |last=Casares |title=Observational evidence for stellar mass black holes |year=2006 |conference=Proceedings of IAU Symposium 238: "Black Holes: From Stars to Galaxies -Across the Range of Masses" |url=http://arxiv.org/abs/astro-ph/0612312}} </ref><ref name = "Garcia-Jets">{{Citation |first1=M.R. |last1=Garcia |first2=J. M. |last2=Miller |first3=J. E. |last3=McClintock |first4=A. R. |last4=King |first5=J. |last5=Orosz |title=Resolved Jets and Long Period Black Hole Novae |journal=Astrophys.J. |volume=591 |year=2003 |pages=388–396 | url=http://arxiv.org/abs/astro-ph/0302230 |doi=10.1086/375218}}</ref> The most distant stellar-mass black hole ever observed is a member of a binary system located in the [[Messier 33]] galaxy.<ref>{{cite journal |author=Orosz, J.A.; et al. |title= A 15.65 solar mass black hole in an eclipsing binary in the nearby spiral galaxy Messier 33 |journal=Nature |volume=449 |pages=872–875 |year=2007 |doi=10.1038/nature06218 |url=http://arxiv.org/abs/0710.3165 |format= subscription required}}</ref>
===Micro black holes===
In theory there is no smallest size for a black hole. Once created, it has the properties of a black hole. [[Stephen Hawking]] theorized that [[primordial black holes]] could evaporate and become even tinier, i.e. [[micro black holes]]. Searches for evaporating primordial black holes are proposed for the [[GLAST]] satellite to be launched in 2008. However, if micro black holes can be created by other means, such as by cosmic ray impacts or in colliders, that does not imply that they must evaporate.
The formation of black hole analogs on Earth in [[particle accelerators]] has been reported. These black hole analogs are not the same as gravitational black holes, but they are vital testing grounds for quantum theories of gravity.<ref>{{arxiv |hep-th |0501068}}</ref>
They act like black holes because of the [[AdS/CFT correspondence|correspondence]] between the theory of the strong nuclear force, which has nothing to do with gravity, and the quantum theory of gravity. They are similar because both are described by string theory. So the formation and disintegration of a [[quark-gluon plasma|fireball]] in quark gluon plasma can be interpreted in black hole language. The fireball at the [[Relativistic Heavy Ion Collider]] [RHIC] is a phenomenon which is closely analogous to a black hole, and many of its physical properties can be correctly predicted using this analogy. The fireball, however, is not a gravitational object. It is presently unknown whether the much more energetic [[Large Hadron Collider]] [LHC] would be capable of producing the speculative large extra dimension micro black hole, as many theorists have suggested.<ref>See [[Safety of particle collisions at the Large Hadron Collider]] for a more in depth discussion.</ref>
== อ้างอิง ==
{{reflist}}
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