Transcript Prezentacja programu PowerPoint

Dark Matter
 Evidence for Dark Matter
 Dark Matter Candidates
 How to search for DM particles?
 Recent puzzling observations (PAMELA, ATIC,
EGRET)
"From neutrinos ....". DK&ER,
lecture13
1
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.
• In 1970-80 –
rotation velocity of
gallaxies; halo of
invisible matter (?)
coma
spherical halo of Dark
Matter surrounding a
gallaxy
Invisible matter, only gravitational interactions
P. Mijakowski
"From neutrinos ....". DK&ER,
lecture13
2
Dark Matter – Bullet Cluster
• 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
• 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
"From neutrinos ....". DK&ER,
lecture13
1E0657-558
(*) D.Clowe et al. 2006 Ap. J. 648
3 L109
P. Mijakowski
Gravitational lensing
Einstein's Bullseyes
Elliptical galaxies
"From neutrinos ....". DK&ER,
lecture13
have DM
halos as spiral
galaxies
4
What do we know about


c
?
Visible matter (stars,
gas):


vis  4,6  0,5 105
Baryons visible or invisible

calculated from BB nucleosynthesis b
Total matter deduced from gravitational
potential energy of galaxies etc.
tot  1,02  0,02
„geometria płaska” k=0
Dark matter:
 0,0420,003
0,005
m  0,240,03
0,04
DM  m  b  0,200,02
0,04
Dark energy:
"From neutrinos ....". DK&ER,
lecture13
  0,760,04
0,06
5
Dark Matter - candidates
• Known particles
< 7% of mass of gallactic halo (exp. EROS)
– MACHO’s (Massive Astronomical Compact Halo
Objects), np. brown dwarfs, neutron stars, black holes
– Neutrinos (Hot Dark Matter - HDM)
• Postulated particles:
structure formation requires
CDM
– Axions
– WIMP-s (Weakly Interacting Massive Particles) - slow,
massive, neutral particles, weakly interacting with matter
(Cold Dark Matter - CDM)
P. Mijakowski
"From neutrinos ....". DK&ER,
lecture13
6
WIMPs
(WIMP – Weakly Interacting Massive Particle)
We are looking for particles:
 Neutral
 With long lifetime
(  ~ Universe lifetime)
 Massive ( M ~ 100 GeV)
 Weakly interacting
Examples of diagrams (neutralino)
  1040 cm2
a good WIMP candidate:
 neutralino  (SUSY) – LSP (Lightest Supersymmetric Particle),
is stable
(conservation of R parity in SUSY)
neutralino( )
18 GeV < M < 7 TeV
LEP
P. Mijakowski
"From neutrinos ....". DK&ER,
lecture13
cosmology
7
Direct Detection
• we measure energy of recoiling nuclei resulting from
elastic scattering of WIMPs
 + (A,Z)at rest   + (A,Z)recoil
Trecoil~ keV
detector
"From neutrinos ....". DK&ER,
lecture13
Very many
experiments are
going on, and new
projects studied
Stay tuned.
8
Direct detection – current experimental limits
WARP(2.3 l. Ar)
DAMA NaI,
90% CL
region
Zeplin II
(Xe)
•
Region above
lines is excluded
with 3CL
•
DAMA 1.1x105 kg·d
(7 years, 100 kg NaI)
•
Hidden assumptions:
–
–
interaction (spin
dependance)
Galactic Halo Model
Edelweiss (Ge)
CDMS II, 2004-05
(Ge) (34 kg·d)
XENON (10kg)
2007, 136 kg·d
CDMS II, 2007
prediction
"From neutrinos ....". DK&ER,
lecture13
9
Indirect detection - neutrinos


Earth
Sun
scatt
capture
annihilation



Z

detektor


In neutrino telescopes no excess of neutrinos from Sun, Earth center, Gallaxy
center when compared to the expected background.
P. Mijakowski
"From neutrinos ....". DK&ER,
lecture13
10
Super-Kamiokande data sample
 1679.6 live days of SK-I
 1892 upward through-going muons
 muon length > 7m
E >1.6 GeV
 effective area: 1200 m2
 angular resolution: 1 deg
Simulation of the background of
atmospheric 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    with m2  0.002 eV2 ,
sin2 2  1
S. Desai PhD thesis
"From neutrinos ....".
DK&ER,et al., PRD D70, 83523 (2004)
11
S.Desai
lecture13
Upward-muons (from ν interactions) -SK
atm. bkg
without oscil
Angles with respect
to direction from:
Earthc
enter
Sun
Galactic
center
with oscil.
with oscil.
 No excess of
neutrinos from the
studied objects
Normalization: total
# of MC events = #
of data events
"From neutrinos ....". DK&ER,
lecture13
 Upper limits on muon
fluxes are calculated
12
Upward muons flux limits from
various experiments
SK
From
Galactic
center
SK
From
Earth’ s center
From
Sun
SK
"From neutrinos ....". DK&ER,
lecture13
13
Muon flux limits as functions of WIMP masses
Wimps of larger mass produce
tighter  beams.
Cones are calculated containing
90% of muons from WIMPs:
Earth’s center
Sun
"From neutrinos ....". DK&ER,
S.Desai etlecture13
al., Phys.Rev.
Galactic center
14
D70 (2004) 083523
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
15
SuperK limit for neutralino elastic
cross section (spin dependent)
Kamionkowski, Ullio, Vogel JHEP 0107 (2001) 044
• 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.)
"From neutrinos ....". DK&ER,
lecture13
16
Some recent observations which
can indicate Dark Matter particles
in Universe
"From neutrinos ....". DK&ER,
lecture13
17
Cosmic-ray Antimatter from Dark
Matter annihilation
Halo
Antimatter particles e , p
can result from:
You are here
 secondary interactions of primary
cosmic rays
 annihilation of WIMPs
gravitationally confined in the galactic
halo
Milky Way
e , p


A plausible WIMP candidate is a neutralino χ, the
lightest SUSY particle





qq

hadrons

p,
e
, .....
Most likely processes:
    W W  , Z0 Z0 ,..  e , .....
"From neutrinos ....". DK&ER,
lecture13
18
PAMELA
a Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics
• 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)
PAMELA
scientific objectives:
»
»
»
»
»
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
"From neutrinos ....". DK&ER,
lecture13
19
PAMELA detector
principle
M. Pearce 2009
"From neutrinos ....". DK&ER,
lecture13
20
PAMELA results (positrons)
best statistics so far: 151672
electrons
positrons
compared to other experiments
9430
• low...in
energy
500 days- in 1.5-100 GeV
solar modulation
effects
– difference
comparing to
CAPRICE, HEAT,
AMS -> previous
solar cycle
• 5-10 GeV
compatibility with
other meas.
• above 10 GeV
– observed increase
(*)
O.Adriani
et al.....".
[PAMELA
Collaboration], arXiv.0810.4994 (Oct
"From
neutrinos
DK&ER,
21 2008)
lecture13
PAMELA results (positrons)
compared to secondary
production
(*) O.Adriani et al. [PAMELA
Collaboration],
arXiv.0810.4995 (Oct 2008)
secondary production
(Moskalenko&Strong)
"From neutrinos ....". DK&ER,
lecture13
spectrum shape
completely different
????
22
ATIC
Advanced Thin Ionization Calorimeter
• 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
"From neutrinos ....". DK&ER,
lecture13
23
"From neutrinos ....". DK&ER,
lecture13
24
ATIC results
(*) J. Chang, et al. [ATIC Collaboration], Nature, 456, 362 (2008)
e+e- flux
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;
"From neutrinos ....". DK&ER,
lecture13
25
Neutralino annihilation fit
to PAMELA & ATIC data
D.Hooper. A.Stebbins ,K.Zurek,
arxiv.0812.3202 (Dec 2008)
secondary production
(Moskalenko&Strong)
ASSUMPTIONS
»
»
WIMPs annihilation only to W+WAnnihilation in nearby clump
• To normalize ATIC & PAMELA
data a very large or dense clump
of DM is required
• -> annihilation rates (per second):
(could be a point source like)
"From neutrinos ....". DK&ER,
lecture13
26
DM annihilation to gammas - EGRET
• EGRET excess in diffuse galactic gamma ray flux
50-100 GeV neutralino annihilation?
"From neutrinos ....". DK&ER,
lecture13
27
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
28