COSMOLOGY AND

COSMIC STRUCTURES

Antonaldo DiaferioDipartimento di Fisica GeneraleUniversità degli Studi di Torino

Torino, 8 aprile 2008

Current collaborators:

Margaret J. Geller & Co. – Harvard-Smithsonian Center for Astrophysics

Klaus Dolag – Max-Planck-Institut für Astrophysik

Stefano Borgani & Co. - Universita' di Trieste

Massimo Ramella – INAF, Oss. Astron. di Trieste

Giuseppe Murante – INAF, Oss. Astron. di Torino

Local group:

Daniele Bertacca, Stefano Camera, Martina Giovalli, Luisa Ostorero, Ana Laura Serra

- Energy content of the Universe

- Clusters of galaxies

- Distribution of galaxies on large scales:

galaxy formation

- Alternative theories of gravity

Outline

THE MATTER/ENERGY CONTENT OF THE UNIVERSE

?

?

WHERE DO WE GET THIS RESULT FROM?

ΩΛ

Ωm

vacuum energy density

geometry

mass density

Early astrophysical evidence of DM

By using Newton/Einstein+ virial theorem:

Coma cluster

GM = 3σ2R ≃100Σmgal

Zwicky 1933

Total cluster mass sum of masses of individual galaxies

The 1980's: X-ray emission

NGC2300 group

m ~ 0.25

Hydra cluster

GM(<r) ~ kBT

Xr (hydro-static eq.)

gas temperature

Strong lensing

Weak lensing

GM(<r) ~ αrc2

m ~ 0.25

deflection angle

Dropping the dynamical equilibrium hypothesis. The 1990's: Gravitational lensing

Dropping the dynamical equilibrium hypothesis: The caustic technique

CL0024 Sky Redshift diagram

CausticsCaustic

amplitude=

escape velocityDiaferio & Geller 1997m ~ 0.25

Diaferio et al. 2005

CLUSTER MASSES: Comparing X-ray, Lensing and Caustics

in three clusters

3D mass profile

projectedmass profile

caustics

lensing

X-ray

THE CENTER FOR ASTROPHYSICS REDSHIFT SURVEY (1978-1999)

20.000 galaxies

Sky projection

redshift survey

redshift 15000 km/s

Milky Way

de Lapparent, Geller & Huchra 1986;Falco et al. 1999

Catalogue of galaxieswith measured positionsand distance (redshift)

The 2dF REDSHIFT SURVEY

The CfA RS

Colless et al 2001

THE FORMATION OF COSMIC STRUCTURES:

CDM

by Ben Moore

THE FORMATION OF COSMIC STRUCTURES

IN CDM MODELS:

Diaferio et al. 1999 (GIF sims.)

DM+Galaxies (semi-analytic modeling)

z=3

z=1

z=2

z=0

From a new redshift survey: SHELS (Geller et al.)

SIMULATIONS WITH ORDINARY (BARYONIC) MATTER: Diffuse IGM

and GalaxiesN-body/hydro-simulations

gas density gas temperature

Borgani et al. 2004

COSMIC STRUCTURES

Forming a cluster

gas density stars

by Klaus Dolag

List of the non-gravitational processes

adiabatic compression

shock heating

radiative heating and cooling

thermal conduction

reionization

star formation and evolution

feedback from supernovae explosion

galactic winds

chemical enrichment

feedback from active galactic nuclei

non-thermal processes (magnetic fields, cosmic ray production)

sub-resolutionprocesses

THE MATTER/ENERGY CONTENT OF THE UNIVERSE

?

?

The standard solution to DM

Supersymmetry (beyond the SM) suggests a number of candidates:

neutralinos, sneutrinos, gravitinos, axinos, ...

but other candidates are axions, sterile neutrinos, “wimpzillas”, ...

However:

neither direct search (accelerators, energy recoil from nucleus hit)

nor indirect search (gamma-ray, neutrino and anti-matter astronomy)

has yet proved the existence of these particles.

The standard solution to DE (I)

Rμν

- ½ gμν

R = 8πG/c4 Tμν

+ Λ gμν

/c2

ρΛ = -p

Λ/c2 = Λc2/8πG

ρΛ → ρ

v

pΛ → p

v = -ρ

vc2

The DE fluid:

The vacuumenergy density interpretation

ρv~ 10-48 GeV4

Einstein-Hilbert action:

SEH

=(16GN)-1 ∫ L (-g)1/2 d4x= (16G

N)-1 ∫ (-g)1/2 R d4x

Can avoid DM & DE:

metric theories L= f(R) where f is arbitrary (e.g. power laws, logarithms, etc.)

additional fields scalar-tensor theories (introduced by Jordan 1955, Brans-Dicke 1961) TeVeS (Bekenstein 2004) STVG (Moffat 2006)

(they have G and other constants varying with time)modification of the nature of the space-time geometry torsion (

not symmetric in : might be relevant for microphysics) non-symmetric metric g (e.g. Moffat: NGT nonsymmetric gravity theory1995,

MSTG=metric skew tensor gravity 2005) generalized Riemann geometry (Weyl, who introduced the conformal

transformations) additional symmetries Conformal gravity (Mennheim 2006)

Can avoid DE only:

from additional space-time dimension of M-theory: brane cosmologies

Zoology of alternative gravities

Ltot = (-g)1/2[R + L(X,)] + Lmatter

X = (-1/2)DD

w=p/(2Xp'-p); p=L

UNIFIED DARK MATTER MODELS

@ high density: DM@ low density: DE

e.g. generalized Chaplygin gasp=-

V(r) = (½) exp(-2) (1+l2/r2) - (½) E2 exp[-)]

ds2=-exp(2)dt2+exp(2)dr2+r2d

Effective spherical potential

The Mannheim-Kazanas (MK) parameterization:

(Walker 1994, Edery & Paranjape 1998, Pireaux 2004a,b)

> 0 0

gravitational potentialdeflection angle

metric

geodesicequation

CONFORMAL GRAVITY BASICS

massive particles: E>0photons: E=0

independent of 2

action

SIMULATION RESULTS

Temperature evolution

2 Mpc

X-ray surf. bright. evolution

Conclusions

By assuming GR, the astrophysical observations imply an overwhelming amount of DM + DE

compared to ordinary matter.

This conclusion rests on the understanding of the astrophysical sources,

and the control of systematics.