Black Hole Radiation  

In General > s.a. equivalence principle; quantum field theory in curved spacetime; quantum black holes.
* Idea: An equilibrium black hole emits thermal radiation corresponding to a temperature TH; An instance of a purely kinematic result from quantum field theory in a curved background Lorentzian geometry containing an event horizon, stating that certain observers will detect a thermal particle state, with temperature depending on horizon properties; In the black hole case, it is interpreted by relaxing the energy conditions that would forbid negative energy particles and a decrease of black hole area, and one concludes that a black hole can radiate energy by creating in its field particle-antiparticle pairs, and swallowing the negative energy particles.
* Transplanckian issue: Because of the infinite gravitational redshift, Hawking quanta emerge from configurations with ultra-high (trans-Planckian) frequencies at the event horizon; Therefore Hawking radiation cannot be derived within a low-energy effective theory, and all derivations make some assumptions concerning Planck scale physics.
* Precursors: Acceleration radiation (Davies), spontaneous radiation from rotation (Unruh).
* Evaporation time: As a consequence of the radiation, a black hole evaporates in a time tH 2560M 3/Nf = 640 NBM/Nf, where Nf = effective number of distinct radiated field modes, and NB:= 4M2/ the Bekenstein number, equal to the entropy for non-rotating black holes.

Special Effects and Properties of Emitted Radiation > s.a. black holes and information; entropy bounds [hyperentropic].
* Nature of radiation: Quanta of all fields that couple to the geometry and to any charges the black hole may have are radiated; In 4D, for T greater than all particle masses, and using standard model parameters, Page estimated that 1.8% of the energy is radiated in scalar particles, 88% in fermions, 9.8% in vectors, and 0.1% in gravitons; In higher dimensions, the gravitational contribution increases.
* Spectrum: Various authors have proposed that it is not exactly thermal, due to (i) Frequency-dependent greybody factors in the potential barrier, (ii) Dynamical nature of black hole background and energy conservation, back-reaction, in the tunneling approach, or (iii) Quantum correlations.
@ Rates and spectra: Page PRD(76), PRD(76), & Hawking AJ(76); Maldacena & Strominger PRD(97)ht/96 [D-branes]; Daghigh & Lapusta PRD(06) [microscopic black holes, p and anti-p]; Boonserm & Visser a0806 [bounds on greybody factors]; > s.a. quantum black holes.
@ Stimulated emission: Bekenstein & Meisels PRD(77); Panangaden & Wald PRD(77).
@ Entropy: Bekenstein PRD(75); Kundt Nat(76)jan.
@ Back-reaction: Balbinot CQG(84); York in(84); Balbinot & Barletta CQG(89); Kraus gq/95-PhD; Zaidi & Gegenberg PRD(98)gq/97; Massar & Parentani gq/98, NPB(00)gq/99; Hu et al gq/99-in; Fabbri et al GRG(01)gq/01, NPB(02)ht/01 [and info paradox]; Ring ht/05 [evaporation rate suppression]; Vilkovisky PLB(06); Maia & Schützhold PRD(07) [toy model].
@ Quantum gravity effects, metric fluctuations: Barrabès et al PRD(99); Wu & Ford PRD(99)gq; Jacobson gq/01-in [and Lorentz violation]; Parentani IJTP(02)-a0705; Agulló et al PRL(06), PRD(07) [short-distance physics]; Thompson & Ford a0803; Schützhold & Unruh a0805, Barceló et al a0807 [modified dispersion relations].
@ Related topics: Jacobson & Kang CQG(93)gq [conformal invariance of T]; 't Hooft NPPS(98)gq/97 [description as effective matter envelope]; Helfer PLA(04)gq [detection and energy extraction]; > s.a. dark energy models; gravitational instantons; types of black holes.

References > s.a. black holes; black hole phenomenology; black holes in modified theories [2D]; Superradiance.
@ Reviews: Traschen gq/00-in; Helfer RPP(03)gq [critical]; Page NJP(05)ht/04-in, ht/06-in.
@ General: Hawking Nat(74)mar [announcement], CMP(75) [original proposal], in(75); Davies JPA(75) [hint from acceleration radiation]; Wald CMP(75); Unruh PRD(76); Hawking PRD(76), SA(77)jan; Unruh PRD(77); Hájícek & Israel PLA(80); Sewell PLA(80) [rigorous, interacting fields]; York PRD(83); Kay in(86); Carlitz & Willey PRD(87); Kay & Wald in(87); Akhmedov et al a0805 [correct semiclassical calculation].
@ And path integral quantum gravity: Hartle & Hawking PRD(76); York & Schmekel PRD(05).
@ And loop quantum gravity: Ashtekar & Bojowald CQG(05)gq [dynamical horizons]; Díaz-Polo & Fernández-Borja CQG(08)-a0706 [isolated horizons].
@ Derivations / models: Gerlach PRD(76) [incipient black hole]; Lapedes PRD(78) [euclidean formalism]; Kraus & Wilczek MPLA(94); Parentani & Piran PRL(94)ht; Scardigli NCB(95)gq/02; Visser IJMPD(03)ht/01 [essential features]; Melnikov & Weinstein ht/01, Weinstein NPPS(02)gq/01-in, ht/02-in [Hamiltonian]; Canfora & Vilasi gq/03 [and trace anomaly]; Kiefer CQG(04)gq [and quasi-normal modes].
@ As tunneling: Berezin et al G&C(99)gq/06; Parikh & Wilczek PRL(00)ht/99; Parikh GRG(04)ht-GRF; Angheben et al JHEP(05) [extremal and rotating]; Medved & Vagenas MPLA(05)gq; Arzano et al JHEP(05)ht; Liu gq/05; Zhang & Zhao PLB(06)gq/05 [charged particles from Kerr-Newman]; Jiang et al PRD(06)ht/05 [rotating]; Ren et al GRG(06) [with topological defects]; Hu et al gq/06 [and laws of black hole dynamics]; Kerner & Mann PRD(06)gq [Taub-NUT]; Wu & Jiang JHEP(06) [BTZ black holes]; Pilling PLB(08)-a0709 [and first law]; Banerjee & Majhi JHEP(08) [beyond the semiclassical approximation].
@ Interpretations: Raval et al PRD(97)gq/96; Visser PRL(98)gq/97; Gupta & Sen PLB(03)ht/02 [geodesic motion on black hole space].
@ Origin: Boulware PRD(76); Hájícek PRD(87); Biernacki CQG(89); Jacobson PRD(96)ht; Kiefer CQG(01)gq [decoherence]; Unruh & Schützhold PRD(05)gq/04 [and Planck-scale physics].
@ Gravitational anomalies approach: Robinson & Wilczek PRL(05)gq; Das et al a0705; Chen & He a0705; Banerjee & Kulkarni PRD(08)-a0707; Peng & Wu a0708-wd [counterexample]; Wu et al CQG(08)-a0803; > s.a. black hole analogs.
@ Related topics: Bowick et al GRG(87) [and strings]; Moffat gq/93 [predictability]; Visser MPLA(93) [black holes as decaying particles]; Verlinde ht/95-in [complementarity]; Visser PRL(98)gq/97 [without black hole thermodynamics]; Corley & Jacobson PRD(98)ht/97 [lattice version]; Parentani PRD(00)gq/99 [and scattering]; Goncharov & Firsova PLB(00)ap; Materassi JHEP(00)ht [conformal nature]; Shankaranarayanan et al MPLA(01) [general covariance]; Casadio CQG(02)ht/01 [dispersion relations]; Valentini ht/04 [and hidden variables]; Saida CQG(06)gq, CQG(07)gq, a0711-in [as non-equilibrium process]; Yu & Zhou PRD(07)-a0707 [spontaneous excitation of atoms]; Banerjee & Kulkarni PLB(08) [from effective action and covariant boundary conditions]; > s.a. Ergosphere.

Arguments for Modified or No Radiation / Evaporation
* T D Lee 1986: Argued that the thermal state is a consequence of a particular choice of state; But, contrary to what he says, it will show up, no matter what state we start with (see also "no hair" theorems), and we cannot have access to information from inside a black hole (we can if somehow we knew already what went inside it).
* A Helfer 2000: Black hole radiation is suppressed by quantum back-reaction effects on matter, and thus on black hole geometry, that set in even at lower energies than the ones involved in black hole radiation calculations.
@ No radiation/evaporation: Lee NPB(86); Belinski PLA(95); Helfer gq/00, RPP(03)gq; Sivaram GRG(01) [in practice]; Nikolic IJMPD(05)ht/04; Chavda & Chavda phy/04 [assumes equilibrium!]; Belinski PLA(06)gq.
@ Non-thermal spectrum: Parikh ht/04 [energy conservation]; Dai & Liu LMP(07) [massive particles].

"Since black holes behave like black bodies, they are not black" – S W Hawking


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