Black-Hole Analogs and Mimickers  

In General > s.a. black holes [alternatives]; emergent gravity [and analog models of spacetime]; modified general relativity.
* Idea: Black-hole analogs and mimickers are objects that may solve Hawking's information-loss paradox and the singularity problem associated with black holes, while reproducing almost all of their classical properties; They are, however, generically unstable on relatively short timescales.
* Remark: Black holes are like spacetime rivers, in that their geometry can be viewed as if space were a moving medium rushing towards their singularities; Horizons are formed where the flow speed exceeds the speed of light such that nothing can escape anymore.
* Black-hole analogs: Systems in which perturbations of a medium (usually acoustic or electromagnetic waves) cannot leave a region of space, for reasons other than spacetime curvature due to gravity; Can often be modeled by an effective curved geometry, and are useful for studying features of black holes, including their possible realization in the lab.
* Black-hole-mimicking spacetimes: Curved spacetimes with properties that make them look like black holes in some ways.
@ General references: Novello et al CQG(03)gq/02 [flowing dielectrics]; Jacobson & Koike cm/02-ch [thin film of 3He-A]; Novello et al ed-02; Schützhold CQG(08)-a1004 [rev]; Schützhold ASL(09)-a1004 [recreating fundamental effects].
@ In BECs: Fabbri NCC(13)-a1212-conf; Boiron et al PRL(15)-a1406 [momentum correlations]; Kühnel PRD(14)-a1312.
@ Radiation: Pauri & Vallisneri FP(99)gq ["electromagnetic radiation" as seen by inertial and accelerated observers]; Robertson JPB(12)-a1508 [introductory tutorial, including dispersion]; Unruh FP(14)-a1401 [measurement already performed in 2010]; Fabbri JPCS(15)-a1411 [in BECs]; Robertson JPB(12)-a1508 [theory]; Thébault a1610 [what can we learn?].
@ Black-hole-mimickers / doubles: Lemos & Zaslavskii PRD(08)-a0806; Guzmán & Rueda-Becerril PRD(09) [boson stars]; Kovács & Harko PRD(10)-a1011 [naked singularities, using accretion disks]; Stadnik et al EPJC(13)-a1210 [resonant scattering of light]; Marunović & Murković CQG(14)-a1308 [boson star and global monopole]; Akhmedov et al PRD(16)-a1601 [energy levels for massive fields as a way to discriminate]; Cardoso et al PRL(16) + news pw(16)apr [mimicking the ringdown signal from black-hole merger]; Holdom & Ren PRD(17)-a1612.
@ Perturbations: Eskin JMP-a0905 [of Kerr black holes]; > s.a. Ergoregion [instabilities].

Analogs, for Acoustic Waves > s.a. sound [differential-geometric approach].
* Idea: Fluid-dynamic analogs of general-relativistic black holes, where the behavior of sound waves in a moving fluid acts as an analog for scalar fields in a gravitational background; The analog of the event horizon occurs where the bulk speed of the fluid coincides with the propagation speed of acoustic waves in the fluid.
* Motivation: Acoustic horizons possess many of the properties normally associated with the event horizons of general relativity, including Hawking radiation, and have received much attention because it would seem to be much easier to experimentally create an acoustic horizon than to create an event horizon; However, so far (2005) the Hawking temperature seems to be too low for radiation to be detected, TH ≈ (10–9/rH(m)) K, because the thermal noise would be too high.
@ Reviews, intros: Visser gq/99-proc; Cardoso phy/05-conf; Jacobson & Parentani SA(05)dec; Lemos a1312-ch [rotating].
@ General references: Jacobson & Volovik PRD(98)cm, JETPL(98)gq [3He]; Parentani IJMPA(02)gq-proc; Cadoni CQG(05) [2D]; Cadoni & Mignemi PRD(05)gq [with singular source]; Ge & Sin JHEP(10)-a1001 [for relativistic fluids]; Ge et al IJMPD(11)-a1010 [from supercurrent tunneling, Josephson effect]; Ge et al PRD(15)-a1508 [not merely an analogy]; Michel et al PRD(16)-a1511 [no-hair theorems].
@ Rotating: Basak & Majumdar CQG(03)gq/02; Visser & Weinfurtner CQG(05)gq/04 [Kerr, equatorial]; Horstmann et al PRL(10)-a0904 [rotating ions in rings, and Hawking radiation]; Lemos a1312-proc [survey and phenomenology]; Garza et al a1802.
@ Other specific examples: Hossenfelder PLB(16) [planar black hole in AdS].
@ Back-reaction: Balbinot et al PRL(05)gq/04, PRD(05)gq/04, NCB(06)gq; Fagnocchi JPCS(06)gq, gq/06-conf.
@ Radiation: Unruh PRL(81), PRD(95)gq/94 [and high-energy dispersion relations]; Visser CQG(98)gq/97; Sakagami & Ohashi PTP(02)gq/01 [experimental model using a Laval nozzle]; Giovanazzi PRL(05)phy/04; Balbinot et al RNC(05)gq/06; Barceló et al CQG(06)gq, PRL(06)gq [quasi-particle creation, no need for trapped region]; Kim & Shin JHEP(07)-a0706, Bécar et al IJMPA(10)-a0808 [anomaly-cancellation method]; Horstmann et al NJP(11)-a1008 [with ions]; Finazzi & Parentani PRD(11)-a1012 [spectral properties], JPCS(11)-a1102 [robustness of spectrum]; Giovanazzi PRL(11)-a1101 [entanglement entropy and mutual information production rates]; Weinfurtner et al PRL(11) [measurement]; Zhang & Zhao PLB(11) [rotating]; Steinhauer nPhys(14) + news ns(14)oct [observation].
@ Thermodynamics: Kim et al JKPS(06)gq/05 [entropy and superradiance]; Zhang AHEP(16)-a1606 [2D].
@ Quasinormal modes: Berti et al PRD(04); Cardoso et al PRD(04) [rotating]; Lepe & Saavedra PLB(05) [and area spectrum]; Saavedra MPLA(06)gq/05; Abdalla et al CQG(07)-a0706 [Laval nozzles]; Dolan et al PRD(12)-a1105 [rotating, draining bathtub model].
@ Other topics: Liberati et al CQG(00)gq [surface gravity]; Schützhold & Unruh PRD(02)gq [gravity waves]; Rosquist GRG(04)gq/03 [and electromagnetic waves]; Choy et al PRD(06) [superradiant energy flow]; Rousseaux et al NJP(10) [surface waves on moving water]; Lombardo & Turiaci PRL(12)-a1206 [decoherence], PRD(13)-a1208 [as open quantum systems]; Benone et al PRD(15)-a1412 [acoustic clouds around black-hole analogs].
@ In Bose-Einstein condensates: Garay et al PRL(00)gq, PRA(01)gq/00; Barceló et al CQG(01)gq/00, IJMPA(03)gq/01 [black-hole radiation]; Visser et al ht/01-conf; Weinfurtner MSc-gq/04; Carusotto et al NJP(08)-a0803 [radiation, numerical]; Lahav et al PRL(10)-a0906 + news physorg(11)jan [created in the lab]; Rinaldi PRD(11)-a1106, IJMPD(13)-a1112 [entropy]; Finazzi PhD(11)-a1208; Anderson et al PRD(14)-a1404 [gray-body factor and infrared divergences]; Steinhauer nPhys(16)-a1510 + comment Leonhardt AdP(18)-a1609, response Steinhauer a1609 [observation, and particle entanglement].
@ Laval nozzles: Furuhashi et al CQG(06)gq; Okuzumi & Sakagami PRD(07)gq [quasinormal ringing, simulations].
@ Other variations: Mayoral et al NJP(11) [white holes, in flowing atomic Bose-Einstein condensates]; Prain & Faraoni a1403 [re turbulent fluid flow].

Analogs, for Electromagnetic Waves
* Optical black holes with fluid vortices: Trap light inside vortices of fluid that whirl at speeds close to the speed of light in the medium (possibly real slow); According to Leonhardt, light brought to a standstill in a gas should produce a singularity analogous to the event horizon of a black hole, and emit pairs of photons similar to Hawking radiation.
* Optical black holes with dielectrics: A dielectric characterized by an electric permittivity εij and magnetic permeability μij, in terms of which the effective fields inside the material are described by the field strength I ab = Z abcd Fcd (> see electromagnetism in media), will behave like a curved geometry gab if Z abcd = (g/γ)1/2 (gac gbdgad gbc).
@ General references: Reznik PRD(00)gq/97 [radiation]; Schäfer & Sauerbrey ap/98 [high-intensity lasers]; Unruh & Schützhold PRD(03)gq [slow light]; Philbin et al Sci(08)-a0711, a0711 + news pw(08)mar [event horizon in optical fibers]; Nation et al PRL(09) + news sn(09)aug [using an array of SQUIDs]; Pereira & Moraes CEJP(11)-a0910 [flowing liquid crystal and equatorial section of Schwarzschild metric]; Belgiorno et al PRL(10) + Dudley & Skryabin Phy(10), comment Schützhold & Unruh PRL(11)-a1012 [using ultrashort laser pulse filaments], comment Liberati et al PRD(12)-a1111; news ns(13)sep [plastic black hole].
@ Radiation: Srinivasan & Padmanabhan gq/98 [from a moving mirror]; Schützhold & Unruh PRL(05)qp/04 [electromagnetic waveguide, proposal].
@ Optical black holes: Leonhardt & Piwnicki PRA(99)phy, PRL(00)cm/99 + pn(00)jan; Visser PRL(00)gq; Brevik & Halnes PRD(02)gq/01; Leonhardt Nat(02)phy/01, gq/01-ch; Royston & Gass gq/02 [with radial flow]; De Lorenci et al PRD(03); Hegde & Vishveshwara a1209 [analytical theory, and effectiuve Schwarzschild solution]; Finazzi & Carusotto PRA(14) [non-linear optical media].
@ Dielectrics: Schützhold et al PRL(02)qp/01; Belgiorno et al PRD(11)-a1003, news disc(10)sep [and Hawking effect]; Belgiorno et al NJP(10)-a1006; Bittencourt et al CQG(14)-a1401 [static dielectrics].
@ Other types: Nguyen et al PRL(15) [analog black hole for microcavity polaritons]; Pikulin & Franz PRX(17) [solid state, black hole on a chip].

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