Cosmological Perturbations – Models and Phenomenology  

In General, Consequences > s.a. content of the universe; tests of general relativity; tests with light [deflection].
* Idea: 2014, Quantum fluctuations associated with the scalar field driving inflation in the early universe "froze in", becoming classical perturbations on top of an otherwise mostly uniform universe, and seeded all observed large-scale structures in the universe; Observations of cmb anisotropies have detected small temperature variations (anisotropies) consistent with predictions from inflation around an energy scale of 1016 GeV (but are not conclusive).
* Spectrum: Primordial fluctuations probably had a flat (scale-invariant) Harrison-Zel'dovich spectrum, in which certain scales get amplified afterwards as a result of acoustic oscillations sloshing around; 2006, WMAP results show deviations from a flat spectrum consistent with inflation [@ news pn(06)mar].
@ General references: Thomas et al PRL(11) + Hudson Phy(11) [excess clustering at large scales]; Vitenti et al PRD(14)-a1311 [Bardeen vs covariant formalism].
@ Primordial fluctuations: Matsumiya et al JCAP(03) [from cmb]; Lyth ap/05 [tensor, r < 16ε bound]; Armendáriz-Picón JCAP(07)ap/06 [state]; Lyth & Liddle 09; Guo et al JCAP(11)-a1105 [from cmb, no convincing deviations from power-law spectrum]; León & Sudarsky Sigma(12)-a1109 [dynamical collapse of the inflaton vacuum state]; Seahra et al JCAP(12) [in scalar field polymer quantization]; Hunt & Sarkar JCAP(14)-a1308 [reconstruction]; Day et al JCAP(14) [from deformed quantum algebras and slow-roll inflation]; Hazra et al JCAP(14)-a1406 [from Planck satellite data].
@ Non-Gaussianity: Brown & Crittenden PRD(05)ap [from magnetic fields]; Cooray PRL(06) [21-cm background anisotropy proposal]; Lehners AiA(10)-a1001 [in ekpyrotic models]; Sadaki & Wands ed-CQG(10); Nurmi et al JCAP(13)-a1301 [and inflation, and observation]; Bruni et al ApJL(14)-a1405 [as signature of Einstein's gravity]; Byrnes a1411-ln; Renaux-Petel CRAS(15)-a1508 [after Planck 2015, rev]; > s.a. Sachs-Wolfe Effect; Trispectrum.
@ Related issues: Christopherson et al PRD(11)-a1008 [vorticity power spectrum]; Armendáriz-Picón JCAP(11) [homogeneity of ensemble mean]; Biswas et al PRD(13)-a1302 [from statistical thermal fluctuations]; Agarwal et al JCAP(14)-a1311 [large-scale structure and initial conditions]; Percival PT(17)dec [baryon acoustic oscillations]; Finke MNRAS(20)-a1902 [Newtonian limit]; > s.a. early-universe cosmology; propagation of gravitational radiation.
@ And observation: Araújo et al ApJ(01)gq [galaxy redshift and counts]; Zaballa et al JCAP(07)ap/06 [constraints from primordial black holes]; Ferreira & Magueijo PRD(08)-a0708 [temperature and fluctuations in the early universe]; Hamann et al JCAP(08) [trans-Planckian ripples]; Coley a0905 [averaging on the null cone]; Ben-Dayan et al PRL(13)-a1207 [luminosity-redshift relation, and dark-energy estimates]; Alonso et al ApJ(15)-a1505 [ultra-large scale perturbations]; Giblin et al ApJ(16)-a1608 [numerical results]; > s.a. matter distribution [structure formation]; observational cosmology [clustering, surveys].
> Back-reaction: see averaging in cosmology; cosmological acceleration and inhomogeneities; cosmological expansion rate.

Specific Models > s.a. cosmological models; chaos in gravitation; FLRW models; inflation [including scalar-tensor theories]; rainbow gravity.
@ Types of matter: Lewis & Challinor PRD(02); Giovannini CQG(05)ap [imperfect fluid]; Demiański et al GRG(05) [realistic dark energy and dark matter]; Langlois & Lepidi JCAP(11)-a1007 [arbitrary number of fluids and transitions, isocurvature non-Gaussianities]; de Vega & Sánchez PRD(12)-a1111, PRD(12)-a1111 [warm dark matter, computational framework and results]; Sawicki et al JCAP(13)-a1208 [imperfect fluid]; Eingorn ApJ(16)-a1509, Brilenkov & Eingorn ApJ(17)-a1703 [pointlike masses]; > s.a. dark energy.
@ Various geometries: Moskaliuk et al HJ(95)ap/06 [non-trivial topology]; Calzetta & Kandus PRD(97)ap/96 [Tolman universe, non-linear evolution]; Tanimoto CM(03)gq [Bianchi II]; > s.a. bianchi-I models and other bianchi models [III].
@ Stability and no-hair: Boucher & Gibbons in(82)-a1109 [exponential approach to de Sitter spacetime and frozen fluctuations during inflation]; Cotsakis & Miritzis CQG(98) [Bianchi]; Bruni et al CQG(02)gq/01 [FLRW metric + dust + cosmological constant]; > s.a. higher-order gravity.
@ Origin, lqg / lqc: Bojowald et al PRD(06)gq, PRL(07)gq/06; Mielczarek & Szydłowski PLB(07)-a0705 [possible test of lqg]; Li et al PRD(12)-a1112 [non-Gaussian features]; Agulló & Morris a1509 [primordial power spectra, detailed numerical exploration]; > s.a. loop quantum cosmology [effects].
@ Other quantum cosmology: Halliwell & Hawking PRD(85) [from no-boundary proposal]; Contaldi et al PLB(99)ap; Hofmann & Winkler ap/04 [singularity-free setting]; Sudarsky JPCS(07)gq/06 [critical view, and proposal]; Mavromatos et al JCAP(13)-a1211 [spacetime foam and defects]; Anderson proc(14)-a1306 [power spectrum, need for numerical work]; Fujita et al PRD(13)-a1306 [from evaporation of primordial black holes]; > s.a. cmb anisotropy.
@ In bounces / cyclic cosmology: Geshnizjani & Battefeld PRD(06)ht/05; Battefeld & Geshnizjani PRD(06); Abramo & Peter JCAP(07)-a0705 [spectrum unaffected]; Cardoso & Wands PRD(08); Wands ASL-a0809 [pre-big-bang]; Brandenberger PRD(09)-a0905 [reddening of spectrum]; Xue & Steinhardt PRL(10)-a1007 [instability of curvature perturbation]; Xue et al PRD(13)-a1308, Kumar PRD(14)-a1310 [evolution through a non-singular bounce]; Biswas et al PRD(16)-a1502; Quintin et al PRD(15)-a1508 [perturbations and non-Gaussianities through a bounce]; Pinto et al a2004 [vector perturbations].
@ Effect of electromagnetic fields: Barrow et al PRP(07); Giovannini PRD(07)-a0707; Kojima & Ichiki a0902 [primordial magnetic fields].

In Other Theories of Gravity > s.a. conformal gravity; hořava-lifshitz gravity; massive gravity; MOND/TeVeS; teleparallel gravity; torsion in physics.
@ General references: Linder & Cahn APP(07)ap [growth of perturbations]; Brandenberger et al PRD(07)-a0706 [from a tachyonic big bang]; Martino et al PRD(09)-a0812 [result of spherical collapse]; Krasnov & Shtanov JCAP(10)-a1002 [deformations of general relativity]; Pogosian et al PRD(10)-a1002 [parametrizing deviations from general relativity]; Chen et al PRD(11), Li et al PRD(11)-a1103 [f(T) theories and large-scale structure]; Silvestri et al PRD(13)-a1302 [practical approach]; Hojjati et al PRD(14)-a1312; Lin & Ishak PRD(16)-a1605 [tensor perturbations]; > s.a. cosmic strings; phenomenology of Lorentz violation.
@ Brane world: Aref'eva et al NPB(00); Giddings et al JHEP(00); Langlois PRD(00)ht, PRL(01)ht/00, et al PRD(01)ht/00; Neronov & Sachs PLB(01); Deffayet PRD(02); Leong et al PRD(02)gq/01; Maartens in(04)ap [rev]; Casali et al PRD(04)ht; Cardoso et al JCAP(07)-a0705; Laszlo & Bean PRD(08)-a0709 [non-linear growth]; > s.a. brane cosmology.
@ f(R) gravity: Koivisto PRD(06)ap; Song et al PRD(07)ap/06; Bean et al PRD(07)ap/06; Ananda et al CQG(09)-a0809; Tsujikawa et al PRD(09)-a0908; Carloni OAJ(10)-a1002 [covariant, gauge-invariant]; Bertacca et al JCAP(12)-a1109; Abebe et al CQG(12)-a1110 [covariant gauge-invariant formalism]; Brax & Valageas PRD(12)-a1205 [structure formation]; Matsumoto PRD(13)-a1303.
@ Other higher-order gravity: Koivisto & Kurki-Suonio CQG(06)ap/05; Faraoni PRD(07)gq [equivalence to scalar-tensor de Sitter background]; Uddin et al CQG(07)-a0705 [comparison of approaches]; Carloni et al PRD(08)-a0707; Pogosian & Silvestri PRD(08)-a0709 [structure growth]; Tsujikawa et al PRD(08)-a0712 [metric and Palatini]; de la Cruz-Dombriz et al PRD(08)-a0802, AIP(09)-a0812; Gannouji et al JCAP(09)-a0809; De Felice et al PRD(10)-a1006; Steigerwald et al JCAP(14) [growth index as probe]; Craps et al JCAP(14)-a1407 [non-local higher-derivative gravity]; Linder PRD(14)-a1407 [relationship between scalar and tensor perturbations].
@ Scalar-tensor gravity: Minamitsuji PLB(14)-a1409 [and disformal transformations]; Lagos et al JCAP(16)-a1604, JCAP(18)-a1711 [and vector-tensor theories].
@ Bimetric gravity: Comelli et al PRD(14)-a1403 [massive]; Cusin et al JCAP(15)-a1505; Lagos & Ferreira JCAP(17)-a1610.
@ Stochastic gravity: Roura & Verdaguer PRD(08)-a0709 [correlations and Einstein-Langevin equation]; Urakawa & Maeda PRD(08)-a0710 [inflaton].
@ Other modified gravity: Cartier et al PRD(01) [string theory]; Grande et al CQG(10)-a1001 [varying G and Λ]; Cembranos et al PRD(13) [Jordan-Fierz-Brans-Dicke theory]; Dirian et al JCAP(14)-a1403 [non-local infrared modifications]; > s.a. unimodular relativity.
> Quantum-gravity effects: see inflationary phenomenology, and planck-scale physics; loop quantum cosmology; perturbations; quantum-gravity phenomenology.

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