Dark Matter: Evidenze, Candidati, Esperimenti

G. ManganoG. Mangano 11

Dark Matter: Evidenze, Dark Matter: Evidenze, Candidati, EsperimentiCandidati, Esperimenti

Gianpiero ManganoGianpiero Mangano

INFN, Sezione di NapoliINFN, Sezione di Napoli

ItalyItaly

22G. ManganoG. Mangano

SummarySummary

A short tour of cosmologyA short tour of cosmology

Observational evidences: baryons vs matterObservational evidences: baryons vs matter

Relic abundance: baryogenesis vs freezingRelic abundance: baryogenesis vs freezing

CandidatesCandidates

ExperimentsExperiments


A basic list of ReferencesA basic list of ReferencesC. Jungman, M. Kamionkowski and K. Griest, Phys. Rept. C. Jungman, M. Kamionkowski and K. Griest, Phys. Rept. 267 (1996) 195267 (1996) 195G. Bertone, D. Hooper and J. Silk, Phys. Rept. G. Bertone, D. Hooper and J. Silk, Phys. Rept. 405 (2005) 279405 (2005) 279S. Dodelson, Modern S. Dodelson, Modern Cosmology, Academic Press 2003Cosmology, Academic Press 2003J. Peacock, Cosmological J. Peacock, Cosmological Physics, Cambridge University Press 1999Physics, Cambridge University Press 1999L. Bergstrom, Rept. Prog. L. Bergstrom, Rept. Prog. Phys. 63 (2000) 793Phys. 63 (2000) 793J. Edsjo,J. Edsjo,

Ph.D Thesis, hep-ph/9704384Ph.D Thesis, hep-ph/9704384


Talks at ISAPP 2006, SorrentoTalks at ISAPP 2006, Sorrento

F. Donato, Dark Matter Particle PhysicsF. Donato, Dark Matter Particle Physics

C. Galbiati, Direct Dark Matter searchesC. Galbiati, Direct Dark Matter searches

R. Battiston, Searching for Dark MatterR. Battiston, Searching for Dark Matter

http://isapp06na.na.infn.it/http://isapp06na.na.infn.it/


A short tour of cosmologyA short tour of cosmology


Main pillars IMain pillars I Cosmic Microwave Background (CMB) Cosmic Microwave Background (CMB)

anisotropiesanisotropies

The Universe is spatially flat

Primordial perturbations are order 10-5

1


Main pillars IIMain pillars II

Big Bang Nucleosynthesis (BBN)Big Bang Nucleosynthesis (BBN)

Baryons contribute for a very tiny fraction of the total energy 002.0023.02 hb


Main pillars IIIMain pillars III Large Scale Large Scale

Structures (LSS) Structures (LSS) SDSS

Primordial perturbations are of the order of 10-5 and grow by gravitational instability

ikxkk e

tPk

k

dkkdttx

2

32

3

3

2

)(

)2(),0( ),(

Main pillars IIIMain pillars III Large Scale Structures (LSS)Large Scale Structures (LSS)


Main pillars IVMain pillars IV

The Hubble lawThe Hubble law

The Universe is presently accelerating

7/3/ m

Main pillars IVMain pillars IV The Hubble lawThe Hubble law


Cosmology:

Einstein Equation (dynamics)

Metric (symmetries)

Equation of state

gTGRgR 82

1

22

2

2222

1)( dr

kr

drtadtds

00 ,)( TPPT i

i


Friedmann equation: equation for expansion rate H

2

22

3

8

a

kG

a

aH

Critical density and energy density fraction

G

Hc

8

3 20

7.0

Mpc s Km 100 -1-10

h

hH

c

ii

Hubble parameter versus redshift z=obs/source-1=1/a-1

23420

2 )1()1()1()( zzzHzH Kmr

3-25

-3229

cm GeV 10

cm g 10 9.1

h

hc


Observational evidences: Observational evidences: baryons vs matterbaryons vs matter


Baryon density• spectra of high redshift quasars

• CMB temperature anisotropies

• primordial nucleosynthesis

b 0.05


Matter density I: mass to light ratio

L

MLM


From galaxy redshift survey the total luminosity density L 108 h L Mpc-3

Stellar population of galaxies 1 - 10

For a critical Universe, =1

M/L 1400 h

For a purely baryonic Universe

M/L 20

A lot of dark matter!


Matter density II: the galactic scale

Rotation curves of (spiral) galaxies

Observation of 21 cm hyperfine line in HI clouds

Flat behavior, well beyond the visible disk

Halo with M r

r

rGMrv

)()(


inner part: cuspy or shallow?

N - body numerical simulation predict a steep profile

observations suggest a universal density profile with an exponential thin stellar disk and a flat core with density 4.5 10-2 (r0/Kpc)-2/3 M pc-3


Elliptic galaxies: debated!

Some show evidence via strong lensing

X-ray emission support the idea of hot gas clouds whose hydrostatic suggest the presence of DM

Other observations on sub/inter galactic scale

•Weak gravitational lensing of distant galaxies by foreground structure

•Velocity dispersion of dwarf spheroidal galaxies: high M/L ratio

•Velocity dispersion of spiral galaxy satellites


Matter density III: the Milky way and the

Oort discrepancy

Comparison of mass density of stars and gas ( = 0.1 M pc-3)

with its dynamical determination via gravitational potential

hydrostatic equilibrium

Unclear result: at most a factor 2 larger than observed density

4)(1 2

diskvz

diskz

P


Matter density IV: the galaxy cluster scale

Measures of cluster mass using virial theorem to the observed velocity of galaxies (Zwicky, 1933 first suggestion observing the COMA cluster)

High M/L = 400 suggesting 0.2 – 0.3

Measures of X-ray emission tracing hot gas clouds in rich clusters

kTm

P

rradr

dP

p

)()(

r

Mpc

M

rMKeVkT

1

10

)()8.13.1(

14


Check via gravitational lensing (measure total mass)

and Sunyaev-Zeldovich effect


Matter density V: the cosmological scale

Two main observables:

CMB temperature fluctuation

Power spectrum of structures on large scales

2||

),(),(

lml

lmlmlm

aC

YaT

T

2

3)(

2

)()(

kkP

ek

dkyx yxik


WMAP

=1

b=0.05

m=0.25




Matter density VI: the local density

Crucial for direct and indirect measurements of DM

Observation of rotation curves of the Milky Way

Typical estimated velocity

<v2>1/2 270 Km s-1


Relic abundance: Relic abundance: baryogenesis vs freezingbaryogenesis vs freezing


The effect of DM on structure formation depends upon its mass

For collisionless DM•Hot DM (relativistic during a large fraction of structure formation) like neutrinos erase perturbations on small scales and produces a top-down scenario (large structure form first, small structure form via fragmentation)

•Cold DM (massive particles > KeV) falls in the initial overdensity gravitational well and produce a bottom–up structure formation scheme (small scale structures form first, large scale via clustering)

CDM scenario is preferred by data: •our galaxy appear to be older than the Local Group

•galaxies are observed at redshift as high as z=4


How massive particles can have a large abundance today?

thermodynamical equilibrium

two possibilities

• some particle – antiparticle asymmetry (baryons): works for CDM

• chemical equilibrium is lost for expansion rate is faster than scattering rate at some stage early stage: scenario for both HDM and CDM

eVTT

emT

n

n TmEQCDM 4

3

/2/3

10 ,1)(


more popular scenario: relic DM via freezing of interactions


Which annihilation rate is required to produce 0.3 ?

Departure from equilibrium: Boltzmann equation

d/dt nDM = collisions

leading to

Weak Interacting Massive Particle (WIMP)

)(3 22 EQCDMCDMCDM

CDM nnvHnt

n

v

scmhDM

103.4 13272


CandidatesCandidates


• Standard Model neutrinos

• sterile neutrinos• axions• wimpzillas

•SUSY particles: neutralino,

gravitino

•Kaluza Klein states

•light scalar DM•mirror particles

•self-interacting DM•light scalar DM•………………….


Cosmological limits on neutrino massOverdensity for a wide range of mass

Neutrinos

From 3H decay and oscillation experiments h2 = 0.07

From WMAP and LSS h2 0.007

Only a very small fraction of can be ascribed to massive neutrinos

Neutrinos are HDM

eV

m

1.93


Neutralino: the best SUSY candidate

The Standard Model: electroweak and strong interactions•Quarks and leptons (fermions)

•Intermediate bosons: 1 massless (photon) + 3 massive (W and Z)+ gluons

•Higgs field: spontaneous symmetry breaking mechanism as a mass generating mechanism


Motivations

1) Hierarchy problem

2) Unification problem


General structure

How to embed the Poincarè and internal symmetries into a larger non trivial symmetry group? Coleman-Mandula-‘O Rafertaigh

Graded Lie algebra

fermionbosonQbosonfermionQ || ||

Superspace

and superfield

,,x

),,( x


The Minimal Supersymmetric Standard Model (MSSM)

R parity The lightest SUSY neutral particle is stable

under decay


Constraints from colliders

Present….

….and future


ExperimentsExperiments


Direct detection: look for scattering of DM off matter

elastic scattering: with <v> = 270 Km/s typical energies

of tens of KeV

inelastic scattering: excitation or ionization after

scattering with electrons: recoil + photon emission in ns

Spin independent: grows with mass of the target

Spin dependent: grows with J(J+1) of the target

Indirect detection: products of DM annihilation in the halo, galaxy, Sun

gamma-ray experiments

neutrino telescopes

positron and antiproton experiments

radio-experiments (syncrhrotron radiation emitted by

electrons and protons propagating in the galactic

magnetic field


Direct detection

mass DM

densityenergy DM

mass Atomic

massDetector

Many experiments:

scintillation (DAMA, ZEPLIN-I, NAIAD, LIBRA)

photons (CREST, DRIFT)

ionization (HDMS; GENIUS, IGEX; MAJORANA, DRIFT)

mixed tecniques (CDMS, Edelweiss, WARP, ZEPLIN-II,

ZEPLIN-III, ZEPLIN-MAX)




Genius

CRESST-II

CDMS-Soudan

Edelweiss-II

WARP

Zeplin-max

CDMS

Zeplin-I

Edelweiss-I


v

cmhDM

2392 103.4


Indirect detection I: Gamma-ray experiments

Space-based: in the GeV-TeV range photons interact with matter via pair production (interaction length 38 g cm-2)

EGRET, GLAST

Ground-based: look for e.m. cascade via Cerenkov light. Large background due to ordinary isotropic Cosmic Rays. MC simulation




Indirect detection II: Neutrino Telescopes: Km3 experiments looking for Cerenkov light of muon tracks after v interaction

under ice under water

Amanda, ICECUBE Antares, Nemo, Nestor




Indirect detection III:Positron and antiproton experiments

PAMELA: antiproton 80 GeV<E<180 GeV

positron 50 MeV <E<270 GeV

Documents

Dark Matter: Evidenze, Candidati, Esperimenti