Dark Matter Evidence for Dark Matter Dark Matter Candidates How to search for DM particles? ...
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Transcript of 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
1
"From neutrinos ....". DK&ER, lecture13
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
"From neutrinos ....". DK&ER, lecture13
• 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
"From neutrinos ....". DK&ER, lecture13
Gravitational lensingEinstein's Bullseyes
4Elliptical galaxies have DM halos as spiral galaxiesElliptical galaxies have DM halos as spiral galaxies
"From neutrinos ....". DK&ER, lecture13
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
"From neutrinos ....". DK&ER, lecture13
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
"From neutrinos ....". DK&ER, lecture13
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
7
"From neutrinos ....". DK&ER, lecture13
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
"From neutrinos ....". DK&ER, lecture13
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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)
"From neutrinos ....". DK&ER, lecture13
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
"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
"From neutrinos ....". DK&ER, lecture13
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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
"From neutrinos ....". DK&ER, lecture13
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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
18"From neutrinos ....". DK&ER, lecture13
"From neutrinos ....". DK&ER, lecture13
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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
"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 ????
22"From neutrinos ....". DK&ER, lecture13
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
23"From neutrinos ....". DK&ER, lecture13
24"From neutrinos ....". DK&ER, lecture13
"From neutrinos ....". DK&ER, lecture13
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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)
26"From neutrinos ....". DK&ER, lecture13
"From neutrinos ....". DK&ER, lecture13
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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??
"From neutrinos ....". DK&ER, lecture13
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