The Standard Cosmological Model  

In General > s.a. cosmology [general issues]; cosmological parameters; general-relativistic cosmology; teaching.
* Idea: It is based on general relativity, homogeneity and isotropy as far as geometry goes, and on simplified features of the standard model of matter and interactions, and it includes (0) A quantum gravity Planck era, (i) A radiation-dominated era (with, or preceded by various possible inflationary variations), (ii) A matter-dominated era and, based on developments since 1997–1998, (iii) A dark-energy dominated era of late-time acceleration.
* Status: 2004–2006, The general consensus favors a ΛCDM model; Together with a theory of perturbations and baryo- and leptogenesis, it essentially fits all observations; 2006–2010, There have been claims that there is evidence for a dynamical dark energy, but the consensus still favors a minimal six-parameter flat ΛCDM "concordance model", which fits the WMAP 7-year data and other observations well; 2012, the concordance ΛCDM model remains the best one to explain the data.
@ Reviews, status: Riotto a1010-ln; Cervantes-Cota & Smoot AIP(11)-a1107; news Sci(13)mar [confirmation by Planck satellite]; Binétruy yr(14)-a1504-ln [and the theory of fundamental interactions]; Bull et al PDU(16)-a1512 [status and promising directions]; Uzan a1606-ln; Raveri et al a1606 [knowledge gain]; Lonappan et al a1705 [assessment].
@ General references: Zhang et al PRL(07)-a0704 [lensing/matter relationship as test for models]; Szydłowski & Tambor a0805 [effective theory, structural stability]; Bartelmann RMP(10)-a0906; Gorbunov & Rubakov 10; Perivolaropoulos JPCS(10)-a1002; Bean & Tangmatitham PRD(10)-a1002 [constraints on deviations]; Trujillo-Gómez et al ApJ(11)-a1005 [and statistics of galaxies]; de Vega et al a1203 [Chalonge school highlights]; Buchert et al IJMPD(16)-a1512-MG14 [observational challenges of FLRW models].
@ Tests: Shafieloo & Clarkson PRD(10)-a0911; Nesseris & Shafieloo MNRAS(10)-a1004; Amara & Kitching MNRAS(11)-a1009; Lombriser PRD(11); Shi et al MNRAS(12)-a1207 [comparison of models]; Martins AIP(13)-a1212 [rev]; Sapone et al PRD(14)-a1402 [testing the FLRW cosmology].

Specific Aspects > see early-universe cosmology; global geometry and topology; inflationary cosmology.

Puzzles and Issues > s.a. dark energy; early-universe nucleosynthesis [lithium-7 problem].
* Issues: 2004-2006, The universe has a "preposterous content", with direct observations accounting for only 1% of total density; Plus, the ΛCDM model has various fudge factors; Could an alternative, "preposterous theory" like MOND, or some other modification of Einstein's gravity, be the way to go? Or could the acceleration be the result of a backreaction to perturbations? How does one carry out the averaging needed to establish a correspondence between the observed universe and a homogeneous one (a.k.a. fitting problem).
* Puzzles and problems: 2010, There is a mismatch between the amount of lithium-7 predicted from big-bang nucleosynthesis and the observed amount (2012, Axions might solve the Li-7 problem); 2013, There are apparent discrepancies with observations on small galactic scales, which ΛCDM must attribute to complexity in the baryon physics of galaxy formation; 2014, The "missing satellites" problem (there are too few satellite galaxies, far fewer than dark matter halos), and the "planes of satellites" problem (the brightest satellites appear to orbit their host galaxies on a thin plane); 2017, the Cusp/Core, Missing Satellites, and Too-Big-to-Fail problems; 2021, The tension between low-redshift (local) and high-redshift (global) values of the Hubble parameter is not going away.
@ General references: Krauss ap/04-ln [dark energy and dark matter]; Scott ap/05-conf; Primack NPPS(07)ap/06 [ΛCDM, vs MOND and other issues]; Perivolaropoulos a0811-fs [puzzles]; Sami a1401-ln; McKay & Wiltshire MNRAS(16)-a1503 [the frame of minimum Hubble expansion variance, and the cmb dipole]; Del Popolo & Le Delliou Gal(17)-a1606 [small-scale issues]; Perivolaropoulos & Skara a2105 [challenges].
@ Low- vs high-redshift measurement tension: Wyman et al PRL(14) [neutrinos can help]; Krishnan et al a2105 [does the FLRW model break down?].
@ Other issues: Nitti et al PRD(05)ht [initial conditions, naturalness]; Lee a1205 [evidence against ΛCDM from the growth function at different redshifts]; Walker & Loeb CP(14)-a1401 [galaxy scaling relations]; Sawala et al a1412 [simulations resolve the main puzzles]; Bullock & Boylan-Kolchin ARAA(17)-a1707 [small-scale challenges]; > s.a. Flatness Problem; large-scale geometry and topology; multiverse; physical constants [cosmology in terms of dimensionless constants]; standard model of particle physics.
@ Critical views: Torretti SHPMP(00); Lieu a0705; Sarkar GRG(08)-a0710 [re evidence for dark matter]; Aisenberg 09; Kundt AIP(09)-a0902; Narlikar & Burbidge 08 [see also the review]; Kroupa PASA(12)-a1204 [dark matter and the two types of dwarf galaxies]; Janzen a1303-FQXi; Kodwani a2006-PhD.

Extensions and Alternatives > s.a. cosmological models [pre-Big-Bang, alternatives to inflation]; MOND.
@ References: Khoury a1312-ln [review of extensions]; Wetterich PLB(14)-a1401 [slow freeze]; Joyce et al PRP(15)-a1407 [current state and future developments]; Di Valentino et al PRD(15)-a1507 [12-parameter extension]; Heavens et al PRL(17)-a1704 [no evidence for extensions]; Solà et al a1909 [BD-ΛCDM cosmology].

main pageabbreviationsjournalscommentsother sitesacknowledgements
send feedback and suggestions to bombelli at – modified 21 may 2021