Transcript Diapositiva 1

COSMOLOGY
AND
COSMIC STRUCTURES
Antonaldo Diaferio
Dipartimento di Fisica Generale
Università degli Studi di Torino
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
Torino, 8 aprile 2008
Outline
- Energy content of the Universe
- Clusters of galaxies
- Distribution of galaxies on large scales:
galaxy formation
- Alternative theories of gravity
THE MATTER/ENERGY CONTENT
OF THE UNIVERSE
?
?
WHERE DO WE GET THIS RESULT FROM?
vacuum energy density
ΩΛ
geometry
mass density
Ωm
Early astrophysical evidence of DM
Zwicky 1933
Total cluster mass
>> sum of masses of individual galaxies
Coma cluster
By using Newton/Einstein
+ virial theorem:
GM = 3σ2R 100Σmgal
The 1980's: X-ray emission
NGC2300 group
Hydra cluster
GM(<r) ~ kBTXr (hydro-static eq.)
gas temperature
m ~ 0.25
Dropping the dynamical equilibrium
hypothesis. The 1990's: Gravitational lensing
Weak lensing
Strong lensing
GM(<r) ~ αrc2
deflection angle
m ~ 0.25
Dropping the dynamical equilibrium
hypothesis: The caustic technique
CL0024
Redshift diagram
Sky
Caustics
Diaferio & Geller 1997
m ~ 0.25
Caustic
amplitude
=
escape velocity
CLUSTER MASSES:
Comparing X-ray, Lensing and Caustics
in three clusters
3D mass profile
caustics
X-ray
lensing
projected
mass profile
Diaferio et al. 2005
THE CENTER FOR ASTROPHYSICS REDSHIFT SURVEY (1978-1999)
20.000 galaxies
Catalogue of galaxies
with measured positions
and distance (redshift)
Sky projection
redshift survey
Milky Way
de Lapparent, Geller & Huchra 1986;
Falco et al. 1999
15000
km/s
The 2dF REDSHIFT SURVEY
Colless et al 2001
The
CfA RS
THE FORMATION OF
COSMIC STRUCTURES:
CDM
by Ben Moore
THE FORMATION
OF COSMIC STRUCTURES
IN CDM MODELS:
DM+Galaxies
(semi-analytic modeling)
z=3
z=2
z=1
z=0
Diaferio et al. 1999 (GIF sims.)
From a new redshift survey: SHELS (Geller et al.)
SIMULATIONS WITH ORDINARY
(BARYONIC) MATTER: Diffuse IGM
and Galaxies
N-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
subresolution
processes
feedback from supernovae explosion
galactic winds
chemical enrichment
feedback from active galactic nuclei
non-thermal processes (magnetic fields, cosmic ray production)
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 gμνR = 8πG/c4 Tμν + Λ gμν/c2
The DE fluid:
The vacuum
energy density
interpretation
ρΛ = -pΛ/c2 = Λc2/8πG
ρΛ → ρv
pΛ → pv = -ρvc2
ρv~ 10-48 GeV4
Zoology of alternative gravities
Einstein-Hilbert action:
SEH=(16GN)-1 ∫ L (-g)1/2 d4x= (16GN)-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
UNIFIED DARK MATTER MODELS
Ltot = (-g)1/2[R + L(X,)] + Lmatter
X = (-1/2)DD 
w=p/(2Xp'-p); p=L
@ high density: DM
@ low density: DE
e.g. generalized Chaplygin gas
p=-
Effective spherical potential
V(r) = (½) exp(-2) (1+l2/r2) - (½) E2 exp[-)]
ds2=-exp(2)dt2+exp(2)dr2+r2d
CONFORMAL GRAVITY BASICS
action
metric
geodesic
equation
photons: E=0
massive particles: E>0
independent of 2
The Mannheim-Kazanas (MK)
parameterization:
gravitational potential
deflection angle
0
> 0
(Walker 1994, Edery & Paranjape 1998, Pireaux 2004a,b)
SIMULATION RESULTS
X-ray surf. bright. evolution
Temperature evolution
2 Mpc
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.