Download Dark Matter and Dark Energy

Dark Matter and Dark Energy
Adel Awad
October 13 2010
Introduction
• Why we care about them?
Introduction
• Why we care about them?
Brief review of
standard cosmology
The Isotropic Universe
First
detection
1965
at 7.35 cm
Penzias & Wilson
Nobel Prize 1978
CMB : tiny anisotropies, huge
information
-200 µK < ΔT < 200 µK
First fine-resolution full-sky map (0.2 degrees)
WMAP: 2003, 2006, 2008
(Launched June 2001)
The Cosmological Principle
• Universe highly isotropic
– CMBR anisotropy  O(10–5)
• Unless we occupy the “center of the Universe,” it
must also be homogenous
• Isotropy and Homogeneity
 maximally symmetric space
– Flat Euclidean space R3
– Closed three-sphere S3
– Open three-hyperbola H3
2
2
2
2
w  x  y z  R
2
2
2
2
2
w  x  y  z  R
2
Friedman Equation
• Equation that governs expansion of the Universe
– k=–1 (closed), k=1 (open), k=0 (flat)
– energy density r
d(rR3 )   pd(R3 ), p  wr
 2
R
k
8




GN r
2
R
R
3
 
• First law of thermodynamics:
3(1w)

r

R
• For flat Universe:
– Matter-dominated Universe
– Radiation-dominated Universe
– Vacuum-dominated Universe
r  R 3 , R  t 2 / 3
r  R 4 , R t 1/ 2
r  R 0 , R  e Ht
Cosmological parameters
• Critical density : put k = 0 today
R
H
R
• Density parameters :
H 02 
(cf. measurements!)
8 GN
rc  rc 
3
8 GN
3H 02
ri (t )
r (t )
i (t ) 
i ,0  i 0
r
rc
andc today:
• Acceleration :
for each fluid i : pi = wi ρi
4 GN
a
1  3w
2

( r  3 p)   H 0 (t )
a
3
2
Hubble’s law
V = H0 D
H0 = 71 ± 4 km/s/Mpc
(Hubble, 1929)
Rem : 1 parsec ~ 3.262 light years ~ 3.1×1013 km
Observational evidence
for Dark Matter
Theoretical Arguments
for Dark Matter
• Spiral galaxies made of bulge+disk: unstable as a
self-gravitating system
 need a (near) spherical halo
• With only baryons as matter, structure starts
forming too late: we won’t exist
– Matter-radiation equality too late
– Baryon density fluctuation doesn’t grow until
decoupling
Galactic Dark Matter
• Observe galaxy rotation
curve using Doppler shifts
Rotation curves & Dark Matter
2
m*vcirc
Gm* M (r )

r
r2
Image UV GALEX, A. Gil de Paz, 2006
“Direct proof” : the Bullet Cluster
• Optical image of merging
clusters (here: 1E 0657-558)
• Reconstruct the shear and the
convergence (grav. lensing)
200 kpc
Clowe et al. ApJL 2006
• Projected density maps
(green contours)
“Direct proof” : the Bullet Cluster
• X-ray image of the same cluster,
1E 0657-558, by Chandra
• Green contours : convergence
 (prop. to the projected density)
200 kpc
• White contours : peaks of  at
68.3%, 95.5% and 99.7% C.L.
Clowe et al. ApJL 2006
 Presence of non-luminous gravitating mass !
Matter census in the Universe
1%
7%
Stars
Gas in virialised structures
7%
Warm/hot gas in IGM
Baryons
Don’t know what Dark Matter is?
Ask a Particle Physicist!
85%
DARK MATTER
Non-baryonic
Mirror Matter
“Dark Matter” candidates
Champs (charged DM)
D-matter
Cryptons
Self-interacting
Superweakly interacting
Braneworld DM
Heavy neutrino
NEUTRALINO
Messenger States in GMSB
“WIMPs”!
Branons
Chaplygin Gas
Split SUSY
Primordial Black Holes
…
L. Roszkowski
WIMP : identity file
• Full name : Weakly Interacting Massive Particle
– Rem : generic name
• Interactions : gravitational, weak nuclear (i.e. « weaker than weak » crosssections)
• Mass : high enough so as to be cold today
• Life time : stable / sufficiently long to have remained until now
• Relic density : Boltzmann equation + freeze-out
27
3 1
3

10
cm
.s
2
χ h 
 v
• Nature?  SUSY?  KK Extra-dimensions?  New Physics!
SUSY & LSP…
• Supersymmetry?
– Extension of the Poincaré algebra:
Q |Boson = |Fermion , Q |Fermion = |Boson
{Q, Q}  P ,
[H,Q] = 0
– Unification of gauge couplings, mass hierarchy (Higgs)
– Keep B & L conservation  R-parity, R = (-1)3B+L(-1)2S
– SM particles : R = +1 SUSY particles : R = -1
• R-parity conservation ( if )
Lightest Supersymmetric Particle stable!
“Natural” candidate for Dark Matter
• MSSM + R-parity  Neutralino :
Extra Universal Dimensions
(EUD)
• Kaluza-Klein : extra dimensions
Compactification of extra dim.
at each pt. of 3D space
Periodical conditions
 Momentum quantification
• EUD : all fields propagate in the 5th dim.
Dark Matter — related experiments: 2010 World Census
Boulby Mine
Soudan Mine
MILAGRO
VERITAS
Frejus
LHC
Canfranc
Gran Sasso
Antares
Nestor
Nemo
Sudbury
STACEE
Tevatron
MAGIC
Baikal
TIBET, ARGO-YBJ
TACTIC
PACT
GRAPES
Neutrino Telescopes
Gamma-ray Telescopes (non-ACT)
Gamma-ray Telescopes (ACTs)
Direct Detection Exps.
Colliders
Observing Satellites
HESS
CANGAROO
Fermi
PAMELA
IceCube (South Pole)
G. Bertone, Particle DM: what comes next?, Seminar @ Tuebingen U.
Observational evidence
for Dark Energy
Type-IA Supernovae
As bright as the
host galaxy
Type-IA Supernovae
• Clear indication for
“cosmological constant”
• Can in principle be
something else with
negative pressure
• With w=–p/r,
r  R3(1w) , R  t 2 / 3(1w)
• Generically called “Dark
Energy”
Cosmic Concordance
• CMBR: flat Universe
~1
• Cluster data etc:
matter~0.3
• SNIA:
(L–2matter)~0.1
• Good concordance among
three
Cosmic Pie
Age : 13.7 billion years
Particle-physics implications
Particle Dark Matter
• Suppose an elementary particle is the Dark Matter
• WIMP (Weakly Interacting Massive Particle)
• Stable heavy particle produced in early Universe,
left-over from near-complete annihilation
• Electroweak scale the correct energy scale!
• We may produce Dark Matter in collider
experiments.
Particle Dark Matter
• Stable, TeV-scale particle, electrically neutral,
only weakly interacting
• No such candidate in the Standard Model
• Supersymmetry: (LSP) Lightest Supersymmetric
Particle is a superpartner of a gauge boson in most
models: “bino” a perfect candidate for WIMP
• But there are many other possibilities (technibaryons, gravitino, axino, invisible axion,
WIMPZILLAS, etc)
Embarrassment
with Dark Energy
• A naïve estimate of the cosmological constant in
Quantum Field Theory: rL~MPl4~10120 times
observation
• The worst prediction in theoretical physics!
• People had argued that there must be some
mechanism to set it zero
• But now it seems finite???
Conclusions
• Mounting evidence that non-baryonic Dark Matter
and Dark Energy exist.
• Immediately imply physics beyond the SM
• Dark Matter likely to be TeV-scale physics
• It is one of the main tasks of LHC experiments to
search for any Dark Matter candidates.