dark matter evidence for dark matter dark matter candidates how to search for dm particles? ...

Dark Matter

Evidence for Dark MatterDark Matter CandidatesHow to search for DM particles? Recent puzzling observations (PAMELA, ATIC, EGRET)

"From neutrinos ....". DK&ER, lecture13

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Dark Matter

• 1933 r. - Fritz Zwicky, COMA cluster. Rotation velocity of gallaxies around common center of mass too large for them to be in a bound system.

Invisible matter, only gravitational interactions

coma

• In 1970-80 – rotation velocity of gallaxies; halo of invisible matter (?)

spherical halo of Dark Matter surrounding a

gallaxy

P. Mijakowski2


• 2006 r. analysis of mass distribution in the region of passing through gallaxy clusters (1E0657-558) (*)

• Gravitational lensing – gravitational potential (images from Hubble Space Telescope, European Southern Observatory VLT, Magellan) / violet

• X-rays - Chandra X-ray Observatory (NASA) /rose

(*) D.Clowe et al. 2006 Ap. J. 648 L109

1E0657-558• Mass of gas typically 2x

larger than the mass of visible matter in gallaxies

• Result: concentration of gravitational mass is where gallaxies are

• Region of X emission:only 10% of the total mass of the system

• Comparison of both observations makes Dark Matter necessary

Dark Matter – Bullet Cluster

P. Mijakowski3


Gravitational lensingEinstein's Bullseyes

4Elliptical galaxies have DM halos as spiral galaxiesElliptical galaxies have DM halos as spiral galaxies


What do we know about ?c

0,040,060,76

0,0030,0050,042b

DM =m−b =0,20−0,04

+0,02

vis = 4,6±0,5( )⋅10−5

m0,24−0,04

0,03

Visible matter (stars, gas):

Baryons visible or invisible calculated from BB nucleosynthesis

Total matter deduced from gravitational potential energy of galaxies etc.

Dark matter:

Dark energy:

1,02 0,02tot

„geometria płaska” k=05


Dark Matter - candidates

• Known particles – MACHO’s (Massive Astronomical Compact Halo

Objects), np. brown dwarfs, neutron stars, black holes

– Neutrinos (Hot Dark Matter - HDM)

• Postulated particles:– Axions – WIMP-s (Weakly Interacting Massive Particles) -

slow, massive, neutral particles, weakly interacting with matter (Cold Dark Matter - CDM)

< 7% of mass of gallactic halo (exp. EROS)

structure formation requires CDM

P. Mijakowski6


WIMPs

(WIMP – Weakly Interacting Massive Particle)We are looking for particles:

Neutral With long lifetime ( τ ~ Universe lifetime) Massive ( Mχ ~ 100 GeV) Weakly interacting

neutralino χ (SUSY) – LSP (Lightest Supersymmetric Particle), is stable (conservation of R parity in SUSY)

a good WIMP candidate:

neutralino(χ) 18 GeV < Mχ < 7 TeVLEP cosmology

Examples of diagrams (neutralino)

P. Mijakowski

σ ≤10−40 cm2

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Direct Detection

Trecoil~ keV

detector

χ + (A,Z)at rest χ + (A,Z)recoil

• we measure energy of recoiling nuclei resulting from elastic scattering of WIMPs

Very many experiments are

going on, and new projects studied

Stay tuned.8


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Direct detection – current experimental limits

• Region above lines is excluded with 3σCL

• DAMA 1.1x105 kg·d (7 years, 100 kg NaI)

• Hidden assumptions:– interaction (spin

dependance)– Galactic Halo Model

DAMA NaI, 90% CL region

CDMS II, 2004-05 (Ge) (34 kg·d)

Edelweiss (Ge)

XENON (10kg)2007, 136 kg·d

CDMS II, 2007prediction

Zeplin II (Xe)

WARP(2.3 l. Ar)


Sun

χ

Earth

μ

χ

σscatt

Γcapture

Γannihilation

νμ

detektor

Indirect detection - neutrinos

In neutrino telescopes no excess of neutrinos from Sun, Earth center, Gallaxy center when compared to the expected background.

χ

χ ν

νZ

P. Mijakowski10

Super-Kamiokande data sample

1679.6 live days of SK-I 1892 upward through-going muons muon length > 7m Eμ>1.6 GeV effective area: 1200 m2

angular resolution: 1 deg

Simulation of the background ofatmospheric neutrinos with:

Bartol fluxes (1996) (event time sampled from data sample) „Nuance” for neutrino interactions muon energy loss in rock – Lipari, Stanev detector simulation oscillations

2 2 2with 0.002 eV , sin 2 1mμ τν ν S. Desai PhD thesisS.Desai et al., PRD D70, 83523 (2004)11"From neutrinos ....". DK&ER,

lecture13

Upward-muons (from ν interactions) -SK

atm. bkgwithout oscil

with oscil.

with oscil.

Normalization: total # of MC events = # of data events

Angles with respect to direction from:

Angles with respect to direction from:

Sun

Galactic center

Earthcenter

No excess of neutrinos from the studied objects

Upper limits on muon fluxes are calculated

No excess of neutrinos from the studied objects

Upper limits on muon fluxes are calculated

12"From neutrinos ....". DK&ER, lecture13

Upward muons flux limits from various experiments

From Earth’ s center From

Sun

FromGalactic center

SK SK

SK13"From neutrinos ....". DK&ER,

lecture13

Muon flux limits as functions of WIMP masses

Wimps of larger mass produce tighter ν beams.

Cones are calculated containing 90% of muons from

WIMPs:

Wimps of larger mass produce tighter ν beams.

Cones are calculated containing 90% of muons from

WIMPs:

Earth’s center Sun Galactic center

S.Desai et al., Phys.Rev. D70 (2004) 08352314"From neutrinos ....". DK&ER,

lecture13


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SuperK limit for neutralino elastic cross section (spin independent interactions)

comparison with direct detection

• Comparison with direct detection: model dependent, assuming only spin-independent interactions in Earth and Sun

• Direct and Indirect event rates:

Evt. rate in 1 kg Ge detector = Evt. Rate in 104-106 m2 of upward muon detector (assuming SI couplings)

» Currently: lowest limit in direct detection -> XENON, ~10-7 pb (10-43 cm2) for a 100 GeV WIMP


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SuperK limit for neutralino elastic cross section (spin

dependent)

• Limit 100 times lower than from direct search experiments• DAMA annual modulation due to axial vector couplings ruled

out by this result (Kamionkowski et al.)

Kamionkowski, Ullio, Vogel JHEP 0107 (2001) 044

Some recent observations which can indicate Dark Matter

particles in Universe


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Cosmic-ray Antimatter from Dark Matter annihilation

A plausible WIMP candidate is a neutralino χ, the lightest SUSY particle

Most likely processes:

You are here Milky Way

Halo

χ + χ → qq → hadrons → p, e+ , .....

χ + χ → W +W − , Z0Z0 ,.. → e+ , .....

χ χ

e+, p

Antimatter particlescan result from:

secondary interactions of primary cosmic rays

annihilation of WIMPs gravitationally confined in the galactic halo

e+, p



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PAMELA

PAMELA

• PAMELA is mounted on satellite Resurs-DK1, inside a pressurized container

• launched June 2006• minimum lifetime 3 years • data transmitted via Very high-speed

Radio Link (VRL)

» Search for dark matter annihilation (e+ and p-bar spectra)

» Search for anti-He (primordial antimatter)

» Study composition and spectra of cosmic rays (including light nuclei)

» Study solar physics and solar modulation

» Study terrestrial magnetosphere and radiation belts

scientific objectives:

a Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics

PAMELA detector principle

M. PearceM. Pearce 200920"From neutrinos ....". DK&ER,

lecture13


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PAMELA results (positrons)

compared to other experiments

(*) O.Adriani et al. [PAMELA Collaboration], arXiv.0810.4994 (Oct 2008)

• low energy -solar modulation effects– difference

comparing to CAPRICE, HEAT, AMS -> previous solar cycle

• 5-10 GeVcompatibility with other meas.

• above 10 GeV– observed increase

best statistics so far: 151672 electrons

9430 positrons

...in 500 days in 1.5-100 GeV

PAMELA results (positrons)

compared to secondary production

(*) O.Adriani et al. [PAMELA Collaboration],

arXiv.0810.4995 (Oct 2008)

secondary production (MoskalenkoStrong)

spectrum shape completely different ????


ATIC• Baloon born experiment for C.R measurement• Operated from McMurdo, Antarctica• ATIC-1 15 days (2000/2001)• ATIC-2 17 days (2002/2003)• flights @ 36km

Advanced Thin Ionization Calorimeter



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ATIC results

ATIC (red points); AMS (green stars); HEAT (open black triangles); BETS (open blue circles), PPB-BETS (blue crosses);

emulsion chambers (black open diamonds); solid curve – galactic spectrum (GALPROP); dashed curve - solar modulated

electron spectrum;

(*) J. Chang, et al. [ATIC Collaboration], Nature, 456, 362 (2008)

e+e- fluxe+e- flux

Neutralino annihilation fit to PAMELA & ATIC data

• To normalize ATIC & PAMELA data a very large or dense clump of DM is required

• -> annihilation rates (per second):

D.Hooper. A.Stebbins ,K.Zurek,

arxiv.0812.3202 (Dec 2008)

ASSUMPTIONS

» WIMPs annihilation only to W+W-

» Annihilation in nearby clump(could be a point source like)

secondary production (MoskalenkoStrong)



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DM annihilation to gammas - EGRET

• EGRET excess in diffuse galactic gamma ray flux

50-100 GeV neutralino annihilation?

Summary

Dark Matter consistently needed to understand various astrophysical observations

According to current studies it constitutes around 24% of the total energy of the Universe

The searches of Dark Matter candidates are going on in various experiments:– direct searches– indirect searches using neutrinos from WIMP annihilation

Recently some puzzling observations (PAMELA, ATIC, EGRET) - could be due to DM??


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dark matter evidence for dark matter dark matter candidates how to search for dm particles? ...

Documents

dark matter evidence

matter cold dark matter

mass of visible matter

spherical halo of dark

dark energy

visible matter stars

ar slide

mass of gas