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 fits
essentially 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.

@ __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].

@ __Low- vs high-redshift measurement tension__:
Wyman et al PRL(14)
[neutrinos can help].

@ __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.

**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 a1704 [no evidence for extensions].

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send feedback and suggestions to bombelli at olemiss.edu – modified 17
jul 2017