COSMOLOGY AND COSMIC STRUCTURES Antonaldo Diaferio Dipartimento di Fisica Generale Università degli...
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Transcript of COSMOLOGY AND COSMIC STRUCTURES Antonaldo Diaferio Dipartimento di Fisica Generale Università degli...
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.