Black Hole - Wikipedia, The Free Encyclopedia

8/12/2019 Black Hole - Wikipedia, The Free Encyclopedia

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Simulated view of a black hole (center) in front ofthe Large Magellanic Cloud. Note the gravitationallensing effect, which produces two enlarged buthighl distorted views of the Cloud. !cross the top,the Milk "a disk appears distorted into an arc.

Black hole#rom "ikipedia, the free encclopedia

! black holeis a region of spacetime where gravitprevents anthing, including light, from escaping.$%&'hetheor of general relativit predicts that a sufficientlcompact mass will deform spacetime to form a blackhole. !round a black hole there is a mathematicalldefined surface called an event horion that marks thepoint of no return. t is called *black* because it absorbsall the light that hits the horion, reflecting nothing, +ustlike a perfect black bod in thermodnamics.$&$-&

uantum mechanics predicts that black holes emitradiation like a black bod with a finite temperature.'his temperature is inversel proportional to the mass ofthe black hole, making it difficult to observe this

radiation for black holes of stellar mass or greater.

/b+ects whose gravit field is too strong for light toescape were first considered in the %0th centur b 1ohnMichell and 2ierre3Simon Laplace. 'he first modernsolution of general relativit that would characterie ablack hole was found b 4arl Schwarschild in %5%6,although its interpretation as a region of space from which nothing can escape was not full appreciated foranother four decades. Long considered a mathematical curiosit, it was during the %567s that theoretical workshowed black holes were a generic prediction of general relativit. 'he discover of neutron stars sparked

interest in gravitationall collapsed compact ob+ects as a possible astrophsical realit.

8lack holes of stellar mass are e9pected to form when ver massive stars collapse at the end of their life ccle.!fter a black hole has formed it can continue to grow b absorbing mass from its surroundings. 8 absorbingother stars and merging with other black holes, supermassive black holes of millions of solar masses ma form.'here is general consensus that supermassive black holes e9ist in the centers of most gala9ies.

:espite its invisible interior, the presence of a black hole can be inferred through its interaction with other matterand with light and other electromagnetic radiation. Matter falling onto a black hole can form an accretion diskheated b friction, forming some of the brightest ob+ects in the universe. f there are other stars orbiting a black

hole, their orbit can be used to determine its mass and location. 'hese data can be used to e9clude possiblealternatives (such as neutron stars). n this wa, astronomers have identified numerous stellar black holecandidates in binar sstems, and established that the core of our Milk "a gala9 contains a supermassiveblack hole of about ;.- million solar masses.

Contents

% vent horion


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Simulation of gravitational lensing b ablack hole, which distorts the image of agala9 in the background (largeranimation)

.- Singularit.; 2hoton sphere.? >rgosphere

- #ormation and evolution-.% =ravitational collapse-. vaporation; /bservational evidence

;.% !ccretion of matter;. @3ra binaries;.- =alactic nuclei;.; >ffects of strong gravit;.? !lternatives

? /pen Auestions?.% >ntrop and thermodnamics

?. nformation loss parado96 See alsoB Notes0 eferences5 #urther reading%7 >9ternal links

History'he idea of a bod so massive that even light could not escapewas first put forward b geologist 1ohn Michell in a letter writtento


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n %5%?, !lbert >instein developed his theor of general relativit, having earlier shown that gravit doesinfluence lightFs motion. /nl a few months later, 4arl Schwarschild found a solution to >instein field eAuations,which describes the gravitational field of a point mass and a spherical mass.$0&! few months afterSchwarschild, 1ohannes :roste, a student of ddington showed that the singularit disappeared after a change of coordinates (see >ddingtonG#inkelsteincoordinates), although it took until %5-- for =eorges LemaHtre to realie that this meant the singularit at theSchwarschild radius was an unphsical coordinate singularit.$%%&

n %5-%, Subrahmanan Chandrasekhar calculated, using special relativit, that a non3rotating bod of electron3degenerate matter above a certain limiting mass (now called the Chandrasekhar limit at %.; solar masses) has nostable solutions.$%&ddington and LevLandau, who argued that some et unknown mechanism would stop the collapse.$%-&'he were partl correctDa white dwarf slightl more massive than the Chandrasekhar limit will collapse into a neutron star,$%;&which isitself stable because of the 2auli e9clusion principle. 8ut in %5-5, obert /ppenheimer and others predictedthat neutron stars above appro9imatel three solar masses (the 'olmanG/ppenheimerGIolkoff limit) wouldcollapse into black holes for the reasons presented b Chandrasekhar, and concluded that no law of phsicswas likel to intervene and stop at least some stars from collapsing to black holes.$%?&

/ppenheimer and his co3authors interpreted the singularit at the boundar of the Schwarschild radius asindicating that this was the boundar of a bubble in which time stopped. 'his is a valid point of view for e9ternalobservers, but not for infalling observers. 8ecause of this propert, the collapsed stars were called *froenstars,*$%6&because an outside observer would see the surface of the star froen in time at the instant where itscollapse takes it inside the Schwarschild radius.

Golden age

See also: Golden age of general relativity

n %5?0, :avid #inkelstein identified the Schwarschild surface as an event horion, *a perfect unidirectionalmembraneD causal influences can cross it in onl one direction*.$%B&'his did not strictl contradict /ppenheimerFsresults, but e9tended them to include the point of view of infalling observers. #inkelsteinFs solution e9tended theSchwarschild solution for the future of observers falling into a black hole. ! complete e9tension had alreadbeen found b Martin 4ruskal, who was urged to publish it.$%0&

'hese results came at the beginning of the golden age of general relativit, which was marked b generalrelativit and black holes becoming mainstream sub+ects of research. 'his process was helped b the discoverof pulsars in %56B,$%5&$7&which, b %565, were shown to be rapidl rotating neutron stars. $%&Jntil that time,neutron stars, like black holes, were regarded as +ust theoretical curiositiesK but the discover of pulsars showedtheir phsical relevance and spurred a further interest in all tpes of compact ob+ects that might be formed bgravitational collapse.

n this period more general black hole solutions were found. n %56-, o 4err found the e9act solution for arotating black hole. 'wo ears later, >ra Newman found the a9ismmetric solution for a black hole that is both

rotating and electricall charged.$&'hrough the work of "erner srael,$-&8randon Carter,$;&$?&and :avidobinson$6&the no3hair theorem emerged, stating that a stationar black hole solution is completel describedb the three parameters of the 4errGNewman metricK mass, angular momentum, and electric charge.$B&


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!t first, it was suspected that the strange features of the black hole solutions were pathological artifacts from thesmmetr conditions imposed, and that the singularities would not appear in generic situations. 'his view washeld in particular b Iladimir 8elinsk, saak 4halatnikov, and >vgen Lifshit, who tried to prove that nosingularities appear in generic solutions.


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Black hole classifications

Class Mass Size

Supermassive black hole %7?G%75MSun 7.77%G%7 !Jntermediate3mass black hole %7-MSun %7

-km R>arth

Stellar black hole %7MSun -7 km

Micro black hole up to MMoon up to 7.% mm

#ar awa from the black hole a particle can move in an direction, asillustrated b the set of arrows. t is onl restricted b the speed oflight.

of an other bod of the same mass.$-0&

Solutions describing more general black holes also e9ist. Charged black holes are described b the eissnerGNordstrm metric, while the 4err metric describes a rotating black hole. 'he most general stationar black holesolution known is the 4errGNewman metric, which describes a black hole with both charge and angularmomentum.$-5&

"hile the mass of a black hole can take an positive value, the charge and angular momentum are constrainedb the mass. n 2lanck units, the total electric charge Qand the total angular momentumJare e9pected tosatisf

for a black hole of massM. 8lack holes saturating this ineAualit are called e9tremal. Solutions of >insteinFseAuations that violate this ineAualit e9ist, but the do not possess an event horion. 'hese solutions have so3called naked singularities that can be observed from the outside, and hence are deemed unphysical. 'he cosmiccensorship hpothesis rules out the formation of such singularities, when the are created through the

gravitational collapse of realistic matter.$;7&'his is supported b numerical simulations.$;%&

:ue to the relativel large strength of the electromagnetic force, black holes forming from the collapse of starsare e9pected to retain the nearl neutral charge of the star. otation, however, is e9pected to be a commonfeature of compact ob+ects. 'he black3hole candidate binar @3ra source =S %5%?O%7? $;&appears to havean angular momentum near the ma9imum allowed value.

8lack holes are commonl classifiedaccording to their mass, independent ofangular momentumJor electric chargeQ. 'he sie of a black hole, asdetermined b the radius of the eventhorion, or Schwarschild radius, isroughl proportional to the massMthrough

where rshis the Schwarschild radius andMSun is the mass of the Sun.$;-&

'his relation is e9act onl for blackholes with ero charge and angular momentumK for more general black holes it can differ up to a factor of .

Event horizon

Main article: Event horizon

'he defining feature of a black hole isthe appearance of an event horionEaboundar in spacetime through which

matter and light can onl pass inwardtowards the mass of the black hole.Nothing, not even light, can escape frominside the event horion. 'he eventhorion is referred to as such because if


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Closer to the black hole spacetime starts to deform. 'here are morepaths going towards the black hole than paths moving awa.$Note %&

nside of the event horion all paths bring the particle closer to the

center of the black hole. t is no longer possible for the particle toescape.

an event occurs within the boundar,information from that event cannot reachan outside observer, making itimpossible to determine if such an eventoccurred.$;?&

!s predicted b general relativit, the

presence of a mass deforms spacetimein such a wa that the paths taken bparticles bend towards the mass.$;6&!tthe event horion of a black hole, thisdeformation becomes so strong thatthere are no paths that lead awa fromthe black hole.

'o a distant observer, clocks near ablack hole appear to tick more slowl

than those further awa from the blackhole.$;B&:ue to this effect, known asgravitational time dilation, an ob+ectfalling into a black hole appears to slow down as it approaches the event horion, taking an infinite time to reachit.$;0&!t the same time, all processes on this ob+ect slow down causing emitted light to appear redder anddimmer, an effect known as gravitational redshift.$;5&>ventuall, at a point +ust before it reaches the eventhorion, the falling ob+ect becomes so dim that it can no longer be seen.

/n the other hand, an observer falling into a black hole does not notice an of these effects as he crosses theevent horion. !ccording to his own clock, he crosses the event horion after a finite time, although he is unableto determine e9actl when he crosses it, as it is impossible to determine the location of the event horion fromlocal observations.$?7&

'he shape of the event horion of a black hole is alwas appro9imatel spherical. $Note &$?-or non3rotating(static) black holes the geometr is precisel spherical, while for rotating black holes the sphere is somewhatoblate.

Singularity

Main article: Gravitational singularity

!t the center of a black hole as described b general relativit lies a gravitational singularit, a region where thespacetime curvature becomes infinite.$?;or a non3rotating black hole, this region takes the shape of a singlepoint and for a rotating black hole, it is smeared out to form a ring singularit ling in the plane of rotation.$??&nboth cases, the singular region has ero volume. t can also be shown that the singular region contains all themass of the black hole solution.$?6&'he singular region can thus be thought of as having infinite densit.

/bservers falling into a Schwarschild black hole (i.e. non3rotating and no charges) cannot avoid being carriedinto the singularit, once the cross the event horion. 'he can prolong the e9perience b accelerating awa to

slow their descent, but onl up to a pointK after attaining a certain ideal velocit, it is best to free fall the rest ofthe wa.$?B&"hen the reach the singularit, the are crushed to infinite densit and their mass is added to thetotal of the black hole. 8efore that happens, the will have been torn apart b the growing tidal forces in aprocess sometimes referred to as spaghettification or the *noodle effect*.$?0&


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n the case of a charged (eissnerGNordstrm) or rotating (4err) black hole, it is possible to avoid thesingularit. >9tending these solutions as far as possible reveals the hpothetical possibilit of e9iting the blackhole into a different spacetime with the black hole acting as a wormhole.$?5&'he possibilit of traveling toanother universe is however onl theoretical, since an perturbation will destro this possibilit. $67&t alsoappears to be possible to follow closed timelike curves (going back to oneFs own past) around the 4errsingularit, which lead to problems with causalit like the grandfather parado9.$6%&t is e9pected that none ofthese peculiar effects would survive in a proper Auantum mechanical treatment of rotating and charged black

holes.$6&

'he appearance of singularities in general relativit is commonl perceived as signaling the breakdown of thetheor.$6-&'his breakdown, however, is e9pectedK it occurs in a situation where Auantum mechanical effectsshould describe these actions due to the e9tremel high densit and therefore particle interactions. 'o date, ithas not been possible to combine Auantum and gravitational effects into a single theor. t is generall e9pectedthat a theor of Auantum gravit will feature black holes without singularities. $6;&$6?&

Photon sphere

Main article: hoton sphere

'he photon sphere is a spherical boundar of ero thickness such that photons moving along tangents to thesphere will be trapped in a circular orbit. #or non3rotating black holes, the photon sphere has a radius %.? timesthe Schwarschild radius. 'he orbits are dnamicall unstable, hence an small perturbation (such as a particleof infalling matter) will grow over time, either setting it on an outward tra+ector escaping the black hole or on aninward spiral eventuall crossing the event horion.$66&

"hile light can still escape from inside the photon sphere, an light that crosses the photon sphere on an inbound

tra+ector will be captured b the black hole.


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region outside of the event horion,where ob+ects cannot remainstationar.

'he outer boundar is sometimes called the ergosurface.

/b+ects and radiation can escape normall from the ergosphere.'hrough the 2enrose process, ob+ects can emerge from theergosphere with more energ than the entered. 'his energ is takenfrom the rotational energ of the black hole causing it to slow down.$65&

Foration and evolution

Considering the e9otic nature of black holes, it ma be natural to Auestion if such biarre ob+ects could e9ist innature or to suggest that the are merel pathological solutions to >insteinFs eAuations. >instein himself wronglthought that black holes would not form, because he held that the angular momentum of collapsing particleswould stabilie their motion at some radius.$B7&'his led the general relativit communit to dismiss all results tothe contrar for man ears.


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! simulated event in the CMSdetector, a collision in which a microblack hole ma be created.

. ,

would have produced black holes of up to %7-solar masses. 'hese black holes could be the seeds of thesupermassive black holes found in the centers of most gala9ies.$B;&

"hile most of the energ released during gravitational collapse is emitted ver Auickl, an outside observer doesnot actuall see the end of this process. >ven though the collapse takes a finite amount of time from thereference frame of infalling matter, a distant observer sees the infalling material slow and halt +ust above theevent horion, due to gravitational time dilation. Light from the collapsing material takes longer and longer to

reach the observer, with the light emitted +ust before the event horion forms is delaed an infinite amount oftime. 'hus the e9ternal observer never sees the formation of the event horionK instead, the collapsing materialseems to become dimmer and increasingl red3shifted, eventuall fading awa.$B?&

Priordial black holes in the Big Bang

=ravitational collapse reAuires great densit. n the current epoch of the universe these high densities are onlfound in stars, but in the earl universe shortl after the big bang densities were much greater, possibl allowingfor the creation of black holes. 'he high densit alone is not enough to allow the formation of black holes since a

uniform mass distribution will not allow the mass to bunch up. n order for primordial black holes to form in sucha dense medium, there must be initial densit perturbations that can then grow under their own gravit. :ifferentmodels for the earl universe var widel in their predictions of the sie of these perturbations. Iarious modelspredict the creation of black holes, ranging from a 2lanck mass to hundreds of thousands of solar masses.$B6&

2rimordial black holes could thus account for the creation of an tpe of black hole.

High!energy collisions

=ravitational collapse is not the onl process that could create blackholes. n principle, black holes could be formed in high3energ

collisions that achieve sufficient densit. !s of 77, no such eventshave been detected, either directl or indirectl as a deficienc of themass balance in particle accelerator e9periments.$BB&'his suggeststhat there must be a lower limit for the mass of black holes.'heoreticall, this boundar is e9pected to lie around the 2lanck mass(m2 P!cQG R %. %7

%5=eIQcR . %7T0kg), where Auantumeffects are e9pected to invalidate the predictions of generalrelativit.$B0&'his would put the creation of black holes firml out ofreach of an high energ process occurring on or near the >arth.

arthFs atmosphere, orpossibl in the new Large N. Uet these theories are ver speculative, and the creationof black holes in these processes is deemed unlikel b man specialists.$07&>ven if micro black holes should beformed in these collisions, it is e9pected that the would evaporate in about %7 T?seconds, posing no threat tothe >arth.$0%&

Gro"th

/nce a black hole has formed, it can continue to grow b absorbing additional matter. !n black hole willcontinuall absorb gas and interstellar dust from its direct surroundings and omnipresent cosmic background


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radiation. 'his is the primar process through which supermassive black holes seem to have grown. $B;&! similarprocess has been suggested for the formation of intermediate3mass black holes in globular clusters.$0&

!nother possibilit is for a black hole to merge with other ob+ects such as stars or even other black holes. 'hisis thought to have been important especiall for the earl development of supermassive black holes, which couldhave formed from the coagulation of man smaller ob+ects.$B;&'he process has also been proposed as the originof some intermediate3mass black holes.$0-&$0;&

Evaporation

Main article: "a#$ing radiation

n %5B;,


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! computer simulation of a star beingconsumed b a black hole. 'he blue dotindicates the location of the black hole.


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accretion disk around a black hole being fedb material from the companion star.

'his animation compares the @3raFheartbeatsF of =S %5%? and =1%B75%, two black holes that ingestgas from companion stars.

'he first strongcandidate for a blackhole, Cgnus @3%,

was discovered in this wa b Charles 'homas 8olton,$56&Louise"ebster and 2aul Murdin$5B&in %5B.$50&$55&Some doubt, however,remained due to the uncertainties resultant from the companion starbeing much heavier than the candidate black hole.$5;&Currentl,better candidates for black holes are found in a class of @3rabinaries called soft @3ra transients.$5;&n this class of sstem thecompanion star is relativel low mass allowing for more accurateestimates in the black hole mass. Moreover, these sstems are onlactive in @3ra for several months once ever %7G?7 ears. :uringthe period of low @3ra emission (called Auiescence), the accretiondisc is e9tremel faint allowing for detailed observation of thecompanion star during this period. /ne of the best such candidates is I;7; Cg.

&uiescence and advection!doinated accretion flo"

'he faintness of the accretion disc during Auiescence is suspected to be caused b the flow entering a modecalled an advection3dominated accretion flow (!:!#). n this mode, almost all the energ generated b frictionin the disc is swept along with the flow instead of radiated awa. f this model is correct, then it forms strongAualitative evidence for the presence of an event horion.$%77&8ecause, if the ob+ect at the center of the disc hada solid surface, it would emit large amounts of radiation as the highl energetic gas hits the surface, an effect thatis observed for neutron stars in a similar state.$5-&

&uasi!periodic oscillations

Main article: Quasi'periodic oscillations

'he @3ra emission from accretion disks sometimes flickers at certain freAuencies. 'hese signals are calledAuasi3periodic oscillations and are thought to be caused b material moving along the inner edge of the accretiondisk (the innermost stable circular orbit). !s such their freAuenc is linked to the mass of the compact ob+ect.'he can thus be used as an alternative wa to determine the mass of potential black holes.$%7%&

Galactic nuclei

See also: %ctive galactic nucleus

!stronomers use the term *active gala9* to describe gala9ies with unusual characteristics, such as unusualspectral line emission and ver strong radio emission. 'heoretical and observational studies have shown that theactivit in these active galactic nuclei (!=N) ma be e9plained b the presence of supermassive black holes.'he models of these !=N consist of a central black hole that ma be millions or billions of times more massivethan the SunK a disk of gas and dust called an accretion diskK and two +ets that are perpendicular to the accretiondisk.$%7&$%7-&

!lthough supermassive black holes are e9pected to be found in most !=N, onl some gala9iesF nuclei havebeen more carefull studied in attempts to both identif and measure the actual masses of the centralsupermassive black hole candidates. Some of the most notable gala9ies with supermassive black holecandidates include the !ndromeda =ala9, M-, M0B, N=C -%%?, N=C --BB, N=C ;?0, and theSombrero =ala9 .$%7;&


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Simulation of gas cloud after closeapproach to the black hole at the

centre of the Milk "a.$%7B&

t is now widel accepted that the center of (nearl) ever gala9 (not +ust active ones) contains a supermassiveblack hole.$%7?&'he close observational correlation between the mass of this hole and the velocit dispersion ofthe host gala9Fs bulge, known as the M3sigma relation, strongl suggests a connection between the formation othe black hole and the gala9 itself. $%76&

Currentl, the best evidence for a supermassive black hole comesfrom studing the proper motion of stars near the center of our own

Milk "a.$%70&Since %55? astronomers have tracked the motion of57 stars in a region called Sagittarius !W. 8 fitting their motion to4eplerian orbits the were able to infer in %550 that .6 million solarmasses must be contained in a volume with a radius of 7.7lightears.$%75&Since then one of the starsEcalled SEhascompleted a full orbit. #rom the orbital data the were able to placebetter constraints on the mass and sie of the ob+ect causing theorbital motion of stars in the Sagittarius !W region, finding that there isa spherical mass of ;.- million solar masses contained within a radius

of less than 7.77 lightears.$%70&

"hile this is more than -777 timesthe Schwarschild radius corresponding to that mass, it is at least consistent with the central ob+ect being asupermassive black hole, and no *realistic cluster $of stars& is phsicall tenable.*$%75&

Effects of strong gravity

!nother wa that the black hole nature of an ob+ect ma be tested in the future is through observation of effectscaused b strong gravit in their vicinit. /ne such effect is gravitational lensingD 'he deformation of spacetimearound a massive ob+ect causes light ras to be deflected much like light passing through an optic lens./bservations have been made of weak gravitational lensing, in which light ras are deflected b onl a few

arcseconds.


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'he formula for the 8ekensteinG


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(ist of unsolved probles in

physics

+s physical information lost in

(lac$ holes,

pressure, etc.). "ithout a satisfactor theor of Auantum gravit, one cannot perform such a computation forblack holes. Some progress has been made in various approaches to Auantum gravit. n %55?, !ndrewStrominger and Cumrun Iafa showed that counting the microstates of a specific supersmmetric black hole instring theor reproduced the 8ekensteinG


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, G

shape or orientation at all.$;;&

. ,'his is true onl for ;3dimensional spacetimes. n higher dimensions more complicated horion topologies

like a black ring are possible.$?%&$?&

-. ,n particular, he assumed that all matter satisfies the weak energ condition.

-eferences

%. ,"ald %50;, pp. 55G-77. ,Schut, 8ernard #. (77-). Gravity from the ground up(httpDQQbooks.google.comQbooksZid2['799h:csC)

. Cambridge Jniversit 2ress. p. %%7. S8N 73?%3;??763?. httpDQQbooks.google.comQbooksZid2['799h:csC.

-. ,:avies, 2. C. ". (%5B0). *'hermodnamics of 8lack


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%;. Yv0oo7C\pg2!%7? . ! 42eters. p. %7?. S8N %3?600%37%3%. httpDQQbooks.google.comQbooksZidkd;I>Yv0oo7C\pg2!%7?.

%?. ^ ab/ppenheimer, 1. .K Iolkoff, =. M. (%5-5). */n Massive Neutron Cores*.hysical Revie#33(;)D -B;G-0%. 8ibcode %5-52hv...??..-B;/ (httpDQQadsabs.harvard.eduQabsQ%5-52hv...??..-B;/) .doiD%7.%%7-Q2hsev.??.-B; (httpDQQd9.doi.orgQ%7.%%7-V#2hsev.??.-B;) .

%6. ,uffini, .K "heeler, 1. !. (%5B%). *ntroducing the black hole*(httpDQQauthors.librar.caltech.eduQ%;5BQ%Quffini775p%6;?2hs['oda.pdf) .hysics -oday(%)D -7G;%.httpDQQauthors.librar.caltech.eduQ%;5BQ%Quffini775p%6;?2hs['oda.pdf.

%B. ,#inkelstein, :. (%5?0). *2ast3#uture !smmetr of the =ravitational #ield of a 2oint 2article*.hysicalRevie#//4(;)D 56?G56B. 8ibcode %5?02hv..%%7..56?#(httpDQQadsabs.harvard.eduQabsQ%5?02hv..%%7..56?#) . doiD%7.%%7-Q2hsev.%%7.56?(httpDQQd9.doi.orgQ%7.%%7-V#2hsev.%%7.56?) .

%0. ,4ruskal, M. (%567). *Ma9imal >9tension of Schwarschild Metric*. hysical Revie#//2(?)D %B;-. 8ibcode%5672hv..%%5.%B;-4 (httpDQQadsabs.harvard.eduQabsQ%5672hv..%%5.%B;-4) . doiD%7.%%7-Q2hsev.%%5.%B;-(httpDQQd9.doi.orgQ%7.%%7-V#2hsev.%%5.%B;-) .

%5. ,ature5/0(?%-7)D B75GB%-,8ibcode %560Natur.%B..B75< (httpDQQadsabs.harvard.eduQabsQ%560Natur.%B..B75ature5.1(?;;-)D -7G-%. 8ibcode%5B;Natur.;0...-7< (httpDQQadsabs.harvard.eduQabsQ%5B;Natur.;0...-7


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-. ,uinion, M. (6 !pril 770). *8lack .K Shafee, .K Naraan, .K emillard, . !.K :avis, S. ".K Li, L.3@. (776). *'he Spin ofthe Near3>9treme 4err 8lack


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. 3 . ..(httpDQQadsabs.harvard.eduQabsQ7762hv:..B;h;77;instein nstitute)) .D %7%7. httpDQQwww.einstein3online.infoQenQspotlightsQaccelerators[bhQinde9.html.

0. ,Iesperini, >.K McMillan, S. L. ".K :F>rcole, !. et al. (7%7). *ntermediate3Mass 8lack arl=lobular Clusters*. -he %strophysical Journal .etters0/7(%)D L;%GL;;. ar@ivD%77-.-;B7(httpDQQar9iv.orgQabsQ%77-.-;B7) . 8ibcode 7%7!p1...B%-L..;%I(httpDQQadsabs.harvard.eduQabsQ7%7!p1...B%-L..;%I) . doiD%7.%700Q7;%307?QB%-Q%QL;%(httpDQQd9.doi.orgQ%7.%700V#7;%307?V#B%-V#%V#L;%) .

0-. ,Ywart, S. #. 2.K 8aumgardt, =>') data for high3energ gamma3ra microsecond bursts*. %strophysical Journal.7.()D ??BG??5. 8ibcode %55;!p1...;-;..??B# (httpDQQadsabs.harvard.eduQabsQ%55;!p1...;-;..??B#) . doiD%7.%706Q%B;B?0(httpDQQd9.doi.orgQ%7.%706V#%B;B?0) .

5%. ,Naee, .. *'esting #undamental 2hsics*(httpDQQwww.nasa.govQmission[pagesQ=L!S'QscienceQtesting[fundamental[phsics.html) . N!S!.httpDQQwww.nasa.govQmission[pagesQ=L!S'QscienceQtesting[fundamental[phsics.html. etrieved 7703753%6.

5. ,*>vent


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. . 3(httpDQQar9iv.orgQabsQastro3phQ55%%06) . doiD%7.%700Q76;35-0%Q%6Q%!Q-7%(httpDQQd9.doi.orgQ%7.%700V#76;35-0%V#%6V#%!V#-7%) .

5?. ,"inter, L. M.K Mushotk, . #.K enolds, C. S. (776). *@MMNewton !rchival Stud of theJltraluminous @a 2opulation in Nearb =ala9ies*. -he %strophysical Journal6.2()D B-7. ar@ivDastro3phQ7?%;07 (httpDQQar9iv.orgQabsQastro3phQ7?%;07) . 8ibcode 776!p1.. .6;5. .B-7"(httpDQQadsabs.harvard.eduQabsQ776!p1...6;5..B-7") . doiD%7.%706Q?76?B5(httpDQQd9.doi.orgQ%7.%706V#?76?B5) .

56. ,8olton, C. '. (%5B). *dentification of Cgnus @3% with 6060*. >ature573(?--6)D B%GB-.

8ibcode %5BNatur.-?..B%8 (httpDQQadsabs.harvard.eduQabsQ%5BNatur.-?..B%8) . doiD%7.%7-0Q-?B%b7(httpDQQd9.doi.orgQ%7.%7-0V#-?B%b7) .

5B. ,"ebster, 8. L.K Murdin, 2. (%5B). *Cgnus @3%Ea Spectroscopic 8inar with a ature573(?--)D -BG-0. 8ibcode %5BNatur.-?...-B"(httpDQQadsabs.harvard.eduQabsQ%5BNatur.-?...-B") . doiD%7.%7-0Q-?7-Ba7(httpDQQd9.doi.orgQ%7.%7-0V#-?7-Ba7) .

50. ,olston, 8. (%7 November %55B). *'he #irst 8lack vidence fora black hole*.%strophysical .etters/6(%)D 5G%. 8ibcode %5B?!pL....%6....5S(httpDQQadsabs.harvard.eduQabsQ%5B?!pL....%6.. ..5S) . doiD%7.%7%6QS7-7;300?-(55)77-0;3;(httpDQQd9.doi.orgQ%7.%7%6V#S7-7;300?-V055V577-0;3;) .

%77. ,Naraan, .K McClintock, 1. (770). *!dvection3dominated accretion and the black hole event horion*. >e#%stronomy Revie#s3/(%7G%)D B--. [email protected] (httpDQQar9iv.orgQabsQ707-.7-) . 8ibcode770New!..?%..B--N (httpDQQadsabs.harvard.eduQabsQ770New!..?%..B--N) .doiD%7.%7%6Q+.newar.770.7-.77 (httpDQQd9.doi.orgQ%7.%7%6V#+.newar.770.7-.77) .

%7%. ,*N!S! scientists identif smallest known black hole* (httpDQQwww.eurekalert.orgQpub[releasesQ77037;Qnsfc3

nsi7;7%70.php) (2ress release). =oddard Space #light Center. 77037;37%.httpDQQwww.eurekalert.orgQpub[releasesQ77037;Qnsfc3nsi7;7%70.php. etrieved 77537-3%;.%7. ,4rolik, 1. uclei (httpDQQbooks.google.comQZ

ido40otMi"gC\printsecfrontcover\dA!ctiveO=alacticONuclei]vonepage\A\ffalse) . 2rincetonJniversit 2ress. Ch. %.. S8N 7365%37%%?%36. httpDQQbooks.google.comQZido40otMi"gC\printsecfrontcover\dA!ctiveO=alacticONuclei]vonepage\A\ffalse.

%7-. ,Sparke, L. S.K =allagher, 1. S. (777). Galaxies in the Aniverse: %n +ntroduction (httpDQQbooks.google.comQZidN0


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llis, =.#.. (%5B-)..arge Scale Structure of space time(httpDQQbooks.google.comQZidag=[4BLl0C) . Cambridge Jniversit 2ress. S8N 73?%3755763;. httpDQQbooks.google.comQZidag=[4BLl0C.Melia, #ulvio (77B). -he Galactic Supermassive *lac$ "ole. 2rinceton J 2ress. S8N 5B037365%3%-%537.'alor, >dwin #.K "heeler, 1ohn !rchibald (777).Exploring *lac$ "oles. !ddison "esle Longman.S8N 737%3-0;-3@.'horne, 4ip S.K Misner, CharlesK "heeler, 1ohn (%5B-). Gravitation. ".


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eview papers

=allo, >lenaK Marolf, :onald (775). *esource Letter 8

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