The dark side of the Universe: dark energy and dark matter

Harutyun Khachatryan

Center for Cosmology and Astrophysics

Content of the Universe after Planck

Density proportion evolution

Lambda chronology

2013 Planck, density content revision

Cosmological modelsFriedmann-Robertson-Walker metric

Continuity equation

Evolution equation

Spatial curvature K=0 flat (Minkowski),K=+1 positive curvature(sphere)K=-1 negative curvature

spectral redshift

cosmic redshift

Friedmann equations

Energy-momentum tensor

Omega budget

Luminosity distance

dark energy 0.69

matter density 0.31

radiation density 10^-4

For concordance model for flat universe

Cosmological constant

Λ?Einstein equations 1916

Einstein 1917

Dark energy 1998Hubble diagram

2011 Nobel Prize in Physics

Extragalactic Distance ladder

Astrophysical parametersL luminosity, total energy emitted by an object per second.

m apparent magnitude, observed brightness.

M absolute magnitude, calibrated brightness.

M=m-5(log10(DL)-1)

Standard candlesClassical Cepheids Type Ia

Supernovae

Cepheid light curve

Type Ia Supernovae

Crab nebula

1054 A.D. supernova remnant

SN Ia light curve

Hubble’s law

V = H r

V- velocity of the galaxy, r- distance to the galaxy,

Hubble’s constant H = 69.32 ± 0.80 (km/s)/Mpc (after Planck).

V=H(r)r

Observations: Hubble redshift-distance law of galaxies

Theory: from FRW metric follows

for small distances, z << 1.

Hubble’s or Lemaitre’s law?

Lemaitre 1927 Hubble 1929

Hubble diagram indicating accelerated expansion

Riess et al. 1998

Higher redshifts: gamma-ray burstersz=1-10 and more (arguable)emits in few seconds as much as the Sun

during its lifetimenature unknown, some empirical relations

exit

Can they be used for the Hubble diagram?

Calibrating GRBs Empirical relations

H. J. M. Cuesta…..H. G. Khachatryan,.. A&A, 2008

Amati relation

lag versus luminosity relation

variability versus luminosity relation

Vacuum fluctuations Zeldovich 1967

Cosmic coincidence

Equation of state, w

Dark energy summaryNegative pressure, p=-ρΩ=0.69Equation of state, cosmological constant w=-

1Various models: vacuum fluctuations,

General Relativity extensions (scalar field coupled, Chern-Simons, f(R), etc), quintessence, holography…

Slide by A.Taylor, Motivating EUCLID space mission, 2011

Dark matter chronology1932- Jan Oort, stellar motion in the local

galactic neighbourhood

1933- Fritz Zwicky, motion in clusters of galaxies

1970- Vera Rubin, galaxy rotation curves

Virial theorem

2<T>=Vtot

Zwicky, F., Helvetica Physica Act 6 (1933)

Coma clusterDark matter

M31 rotation curve

V.C. Rubin & W.K. Ford 1970

Galaxy rotation curves

Gravitational lensing

Einstein 1912,1936

Bullet cluster

1E 0657-558

Bullet cluster X-ray image

Modified Newtonian dynamics

MOND theory (by Milgrom)MOND acceleration related to the Newtonian acceleration aN

at weak acceleration limit of gravity

interpolation function

Dark matter summary Ω=0.27Particle candidates: axion, WIMPs, neutrino

(small part), supersymmetric particles…Models: cold dark matter, warm dark matter,

hot dark matterMOND

Challenge to homogeneity of the Universe?

Greatest cosmic structure

73 quasar cluster

z=1.27, longest dimension 1240 Mpc, mean length 500 Mpc

R. Clowes et al. MN, 2013

Conclusions•Modern cosmology passed to the precision cosmology era.•Dark energy: favored, cosmological constant w=-1. The nature unknown. •Dark matter: many candidates, none favored. The nature unknown.•Challenges to the concordance model (CMB low multipole anomaly, alignments, non- Gaussianities…).