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KIT – University of the State of Baden-Württemberg and
National Research Center of the Helmholtz Association
Guido Drexlin, Institut für Experimentelle Kernphysik
www.kit.edu
Guido Drexlin, Institut für Experimentelle Kernphysik
Dark Matter – I
GRK 1694: Elementarteilchenphysik bei höchster Energie und höchster Präzision
Workshop Freudenstadt 2015
KIT-IEKP2 Sept. 28, 2015 G. Drexlin – DM1
dark matter –
30-50 t Lxe
TPC Ø > 2 m
KIT-IEKP3 Sept. 28, 2015 G. Drexlin – DM1
outline of lectures
Dark Matter – 1
- introduction
- astrophysical evidences for DM
- thermal relics & freeze-out
- non-thermal relics: sterile n´s
- WIMP candidates
- experimental searches
Dark Matter – 2
- indirect searches: principles & (selected) results
Dark Matter – 3
- direct detection: experiments & (selected) results
KIT-IEKP4 Sept. 28, 2015 G. Drexlin – DM1
introduction - a brief history of dark matter
KIT-IEKP5 Sept. 28, 2015 G. Drexlin – DM1
a buzz of excitement or the final round?
see 2014 lectures by
I. Melzer-Pellmann, DESY Hamburg :
„SUSY Searches at the LHC“
LHC searches
not covered here
KIT-IEKP6 Sept. 28, 2015 G. Drexlin – DM1
a buzz of excitement or the final round?
Sept. 10, 2015: XMASS - new results
Sept. 15, 2015: MiniCLEAN – starting up
Nov. 11, 2015:
XENON1T
inauguration
KIT-IEKP7 Sept. 28, 2015 G. Drexlin – DM1
a buzz of excitement or the final round?
(too?) many astrophysical evidences for dark matter keV – MeV – GeV …
c0~1
nR
a
KIT-IEKP8 Sept. 28, 2015 G. Drexlin – DM1
dark matter – galactic halo
flat rotation curves imply extended dark matter halos (V. Rubin) :
- DM halos contain 80-90% of entire mass of a galaxy
- detailed modelling gives ´universal´ NFW-profile
M(r) ~ r
r(r) ~ 1/r2
DM halo
2
0
1
)(
SS
DM
R
r
R
rr
rr
KIT-IEKP9 Sept. 28, 2015 G. Drexlin – DM1
dark matter – galactic halo
flat rotation curves imply extended dark matter halos (V. Rubin) :
- DM halos contain 80-90% of entire mass of a galaxy
- detailed modelling gives ´universal´ NFW-profile
- clumpy sub-structure (DM simulations)
2
0
1
)(
SS
DM
R
r
R
rr
rr
KIT-IEKP10 Sept. 28, 2015 G. Drexlin – DM1
dark matter – galactic halo
flat rotation curves imply extended dark matter halos (V. Rubin) :
- DM halos contain 80-90% of entire mass of a galaxy
- detailed modelling gives ´universal´ NFW-profile
- clumpy sub-structure (DM simulations)
- DM halos from virialization of dissipation-less WIMPs
& tidal disruption of ´primoridal´ DM halos
2
0
1
)(
SS
DM
R
r
R
rr
rr
DM: WIMP interactions
spherical halo
virialization
dissipation-less
angular momentum
conservation
only gravitation
KIT-IEKP11 Sept. 28, 2015 G. Drexlin – DM1
dark matter – rotation curve of Milky Way
distance to galactic centre (kpc)
3 5 10 20
vro
t(k
m s
-1kpc
-1) observation
baryonic models
resid
.
reference
100
50
20
R0 = 8 kpc v0 = 230 km s-1
NFW model
c2/n
df
60
0
-6010
10.1
F. Iocco et al.,
2015
Nature Physics
inner
cuto
ff
r =
2.5
kpc
KIT-IEKP12 Sept. 28, 2015
rWIMP = 50 GeV/150 cm3
local DM density
local DM density much higher than cosmological mean DM density
halo density profile r(r)~1/r2
milky way
r(r)
vrot = 230 km/s
r = 8 kpc
r
estimate: from solar rotation speed vrot to rlocal
local DM-density r:
important parameter
for directe WIMP
searches
DMlokalDM rr 5
, 10
≈ rbaryonic
rDM,local ~ 0.3 GeV/cm3
r 3
3
4rMrwith2
2v
r
GM
r
rrot
Gr
rotlocal 2
2
4
v3
r
mass?
G. Drexlin – DM1
KIT-IEKP13 Sept. 28, 2015 G. Drexlin – DM1
dark matter – galaxy clusters
first postulation of dark matter (F. Zwicky, 1933) :
- DM: non-luminous matter, interacts only via gravitational forces
explains the very high peculiar velocities of single galaxies
in the Coma galaxy cluster
Coma Cluster: 1000 galaxies in d = 120 Mpc
F. Zwicky
Helv. Phys. Acta 6
110-127 (1933)
´Die Rotverschiebung
von extragalaktischen
Nebeln´
virial theorem: potkin UE2
1
C153 in Abell 2125
non-luminous matter
~ 90% of the mass
in Coma cluster…
KIT-IEKP14 Sept. 28, 2015 G. Drexlin – DM1
Dark matter – galaxy cluster 1E 0657-556
M~1015M
M~1014M
Bullet
Cluster
d =1 Gpc
z = 0.296
KIT-IEKP15 Sept. 28, 2015 G. Drexlin – DM1
mapping of dark matter - Abell 901/902
distribution of dark matter (weak lensing) & baryonic matter
KIT-IEKP16 Sept. 28, 2015 G. Drexlin – DM1
2015 update: DM map from DE survey
Dark Energy Survey:
- large-scale weak lensing studies
520 Megapixel
CCD
4 m Blanco
telescope
at Cerro Tololo
KIT-IEKP17 Sept. 28, 2015 G. Drexlin – DM1
2015 update: DM map from DE survey
Dark Energy Survey:
- large-scale weak lensing studies
DM forms large filaments
KIT-IEKP18 Sept. 28, 2015 G. Drexlin – DM1
dark matter – cosmological scalesT-f
luctu
ationsD
T2
(µK
2)
angular scale Q
multipole moment ℓ
- overall fraction of dark matter
WDM h2 = 0.1199 ± 0.0027
baryon acoustic
oscillations
LCDM concordance
model
KIT-IEKP19 Sept. 28, 2015 G. Drexlin – DM1
Lee-Weinberg curve for HDM & CDM
ho
td
ark
matt
er
10-1 100 101 102 103 104 105 106 107 108 109 1010
dominant DM part
WIMP-
mass M (eV)
HDM: relativistic free-streaming after decoupling, no annihilation processes
thus: WHDM ~ M, result: HDM particle density not reduced
HDM:
M << Tfr
energ
ydensityW
DM
105
104
103
102
101
100
10-1
M = Tfr
이휘소 Wein-
berg
KIT-IEKP20 Sept. 28, 2015 G. Drexlin – DM1
co
ldd
ark
matt
er
10-1 100 101 102 103 104 105 106 107 108 109 1010
WIMP-
mass M (eV)
CDM: non-relativistic before decoupling, strong annihilation processes
with sAnn ~ M2, result: CDM particle density extremely reduced
M = Tfr
M >> Tfr
HDM:
M << Tfr
105
104
103
102
101
100
10-1
WDM = 0.27
energ
ydensityW
DM
Lee-Weinberg curve for HDM & CDM
ho
td
ark
matt
er
dominant DM part
KIT-IEKP21 Sept. 28, 2015 G. Drexlin – DM1
co
ldd
ark
matt
er
10-1 100 101 102 103 104 105 106 107 108 109 1010
WIMP-
mass M (eV)
CDM/HDM: only two narrow regions remain for thermal relics from Big Bang
very light neutrals (meV-eV neutrinos), heavy neutralinos (TeV)
105
104
103
102
101
100
10-1
WDM = 0.27
energ
ydensityW
DM
Lee-Weinberg curve for HDM & CDM
ho
td
ark
matt
er
dominant DM part
meV-
eV
GeV-
TeV
KIT-IEKP22 Sept. 28, 2015 G. Drexlin – DM1
WIMPs – thermal relics of the early universe
10-8 s:
WIMPs
propagate
freely
10-9 s:
final WIMPs
annihilate
Hubble-
expansion
freeze-out
of WIMPs
Big Bang
thermo-
dynamic
equilibrium
ttT 1~)(
KIT-IEKP23 Sept. 28, 2015 G. Drexlin – DM1
WIMPs in radiation-dominated universe
time t (ns)
10 1
100 101 102 103
mc = 100 GeV10-4
10-8
10-12
10-16
annihilation and
production of WIMPs
´co
-mo
vin
g´
pa
rtic
led
en
sity
nc(T
)
temperature T (GeV)
thermal
equilibrium
)(tH
exponential
decrease of
WIMP density
TkM BWIMPetn/
~)(
c
KIT-IEKP24 Sept. 28, 2015
thermal
equilibrium
´co
-mo
vin
g´
pa
rtic
led
en
sity
nc(T
)
temperature T (GeV)10 1
time t (ns)100 101 102 103
mc = 100 GeV10-4
10-8
10-12
10-16
108
104
100
10-4
WDM
moment of WIMP
decoupling:
WIMP-density
WDM = 100
WIMP-density
WDM = 0.001
WDM = 0.27
)()( tHti
G. Drexlin – DM1
WIMP decoupling and WDM
1(t) 2(t) 3(t)
KIT-IEKP25 Sept. 28, 2015 G. Drexlin – DM1
WIMP decoupling to WDM = 0.27
thermal
equilibrium
´co
-mo
vin
g´
pa
rtic
led
en
sity
nc(T
)
temperature T (GeV)10 1
time t (ns)100 101 102 103
10-4
10-8
10-12
10-16
108
104
100
10-4
WDM
moment of WIMP
decoupling:
)()( tHti
1(t) 2(t) 3(t)
n~
sneutrinos (LH)
Interact too strong
KIT-IEKP26 Sept. 28, 2015
WIMP decoupling to WDM = 0.27
mc = 100 GeV
G. Drexlin – DM1
WDM = 0.27
thermal
equilibrium
´co
-mo
vin
g´
pa
rtic
led
en
sity
nc(T
)
temperature T (GeV)10 1
time t (ns)100 101 102 103
10-4
10-8
10-12
10-16
108
104
100
10-4
WDM
moment of WIMP
decoupling:
)()( tHti
KIT-IEKP27 Sept. 28, 2015
WIMP ´miracle´ & annihilation rate
T (GeV)10
100 101
10-4
10-8
10-12
10-16
)()( frfri tHt
132510
~)0(
W scmvAnns
c
for v ~ 0.3 c at WIMP decoupling
one obtains for Wc ~ 0.27
the WIMP ´miracle´:
WIMP density Wc(0) today & sAnn:
sAnn ~ 10-36 cm2
G. Drexlin – DM1
weak interaction
´co
-mo
vin
g´
pa
rtic
led
en
sity
nc(T
)
time t (ns)
KIT-IEKP28 Sept. 28, 2015
T (GeV)10
100 101
10-4
10-8
10-12
10-16
)()( frfri tHt
mc = 100 GeV
time of WIMP-freeze-out: t ~ few ns
non-relativisitic propagation
20~fr
frT
Mx
c
20~
cMT fr
CDM: Mcc2 >> kBTfreeze out
WIMPs after freeze-out act as
CDM (cold dark matter)
Tfr = 5 GeV
G. Drexlin – DM1
´co
-mo
vin
g´
pa
rtic
led
en
sity
nc(T
)
time t (ns)
WIMP decoupling – non-relativistic
KIT-IEKP29 Sept. 28, 2015 G. Drexlin – DM1
structure formation with CMD, WDM, HDM
CMB
LSS
z =
1100z =
0
structure evolution
top-
down
scenario
ne,µ,t
WDMnsterile
bottom-
up
scenario
c0
KIT-IEKP30 Sept. 28, 2015 G. Drexlin – DM1
comparison of DM-models with observations (<rDM> ~ 1 keV/cm³):
wash-out on different length scales (lfree-streaming)
Hot Dark Matter HDM
particles:
active neutrinos ne,µ,t
m ~ 0.05 – 2 eV
WarmDarkMatter WDM
particles:
sterile neutrinos ns
m ~ 1 – 20 keV
Cold Dark Matter CDM
particles:
SUSY neutralinos c0
m ~ 10 – 1000 GeV
number density:
N(active): 339/cm3
decoupling:
T = 2 – 3 MeV
T/m ~ 106 – 107
number density:
N(sterile): ~0.1-1/cm3
decoupling:
none, produced via
n-oscillations
Number density:
N(c0): 10-7-10-9/cm3
decoupling:
T = 0.5 – 50 GeV
T/m ~ 1/20
LSS implication:
wash-out on scales
l < 1 Gpc
LSS implication:
wash-out on scales
l < 100 kpc
LSS implication:
wash-out on scales
l < 0.1 pc
dark matter: hot, warm or cold?
KIT-IEKP31 Sept. 28, 2015 G. Drexlin – DM1
comparison of DM-models with observations (<rDM> ~ 1 keV/cm³):
wash-out on different length scales (lfree-streaming)
Hot Dark Matter HDM
particles:
active neutrinos ne,µ,t
m ~ 0.05 – 2 eV
WarmDarkMatter WDM
particles:
sterile neutrinos ns
m ~ 1 – 20 keV
Cold Dark Matter CDM
particles:
SUSY neutralinos c0
m ~ 10 – 1000 GeV
LSS implication:
wash-out on scales
l < 1 Gpc
LSS implication:
wash-out on scales
l < 100 kpc
LSS implication:
wash-out on scales
l < 0.1 pc
dark matter: hot, warm or cold?
KIT-IEKP32 Sept. 28, 2015 G. Drexlin – DM1
keV-scale sterile neutrinos would be produced via non-thermal processes
and act as CDM/WDM in evolustion of LSS
intermission: keV-scale sterile neutrinos
WarmDarkMatter WDM
particles:
sterile neutrinos ns
m ~ 1 – 20 keV
LSS implication:
wash-out on scales
l < 100 kpc
particle physicsastrophysics
nMSM – a SM extension
(Shaposhnikov et al 2013)
a faint X-ray line at
3.5 keV in clusters?
(Bulbul et al 2014)
KIT-IEKP33 Sept. 28, 2015 G. Drexlin – DM1
KATRIN – a novel detector system for ns
Cover entire phase-space of T2 ß-decay
search for kink-like structure well
below E0 = 18.6 keV
shape modification by keV-mass
sterile neutrino with mass ms
KIT-IEKP34 Sept. 28, 2015 G. Drexlin – DM1
KATRIN – a novel detector system for WDM
Cover entire phase-space of T2 ß-decay
search for kink-like structure well
below E0 = 18.6 keV
- main spectrometer operated at
variable retarding potential (0-18.6 keV)huge signal rates O (1010 cps)
- need detectors with energy resolution
of DE ~ 300 eV for kink identification
KIT-IEKP35 Sept. 28, 2015 G. Drexlin – DM1
TRISTAN – R&D on detector technology
TRISTAN – TRitium beta decay Investigation on Sterile To Active Neutrino mixing
(S. Mertens et al.)
- promising differential read-out
technology:
p-type point contact detectors
array with 104 pixels
KIT-IEKP36 Sept. 28, 2015 G. Drexlin – DM1
KATRIN – sensitivity to keV-scale sterile n´s
sensitivity estimates for 3 full KATRIN years
- investigation of systematics (detector,
weak interactions)
wavelet approach