1. Dark Matter in the Universe physics beyond the standard model
why not neutrinos
how to detect
Dark Matter particles
Josef Jochum
Eberhard Karls Universität Tübingen
Kepler Center for Astro and Particle Physics

2. many astrophysical observations point to Dark Matter ?
orbital motion around Galaxies
or motion of galaxies in galaxy clusters
too fast
gravity potential and distribution
of visible matter do not coincide
light deflection shows
higher gravity potentials
than expected from visible matter

3. Anisotropy of Comsic Microwave Background
2009
2001 Tü
Wilkinson Microwave Anisotropy Probe

4. Cosmic Microwave Background
CMB
Universe transparent
Universe
not transparent
Neutrinomasse !!
Foto: Franko Fürstenhoff

5. tiny anisotropy ~ dT / T ~ 10-5 shows density variation
CMB measurement
perfect black body T = 2.73K
tiny anisotropy ~ dT / T ~ 10-5
shows density variation
at (re)-combination
p + e H + g
CMB:
t = years
z = ; T ~ 3000K; kT ~ 0,3 eV
Universe was 1100 times smaller
scale factor: R = 1 today, R = 1 / 1100 at (re)-combination Tü

6. shows the oscillation modes which are at maximum compression or
compression and
decompression peaks
Power Spectrum
shows the oscillation modes which are at maximum compression or
maximum expansion at the time of (re)combination

7. did this anisotropy grow to todays structure ?

8. Structure Formation in the Universe
density r; pressure p, speed v, gravity potential F
continuity eq.
Euler eq.
Poisson eq.
density contrast
variation
average density =

9. Structure Formation in the Universe
density r; pressure p, speed v, gravity potential F
continuity eq.
no structure growth
as long as particles
are relativistic kT > mc2
Euler eq.
once density contrast d grows,
it grows like the scale factor
d ~ R ~ 1/T
d x 1100
since (re)combination
today 2,7K – recomb ~ 3000 K
Poisson eq.
density contrast
variation
average density =

10. Structure Formation in the Universe
density r; pressure p, speed v, gravity potential F
continuity eq.
linearisation:
r0 etc. homogeneous
r1 (x,t) etc. small disturbation
Euler eq.
Poisson eq.
density contrast

11. Structure Formation in the Universe
density r; pressure p, speed v, gravity potential F
“wave eq“ with gravity
sound speed

12. Structure Formation in the Universe
density r; pressure p, speed v, gravity potential F
“wave eq“ with gravity
pressure term
sound speed

13. Structure Formation in the Universe
density r; pressure p, speed v, gravity potential F
“wave eq“ with gravity
densitiy only oscillates
no structure growth
as long as pressure term is large
>

14. Structure Formation in the Universe
pressure term needs to be small or disappearing
<
structure growth (growth of d) only at scales larger than Jeans length lJ

15. Structure Formation in the Universe
structure growth (growth of d) only if
=>
expansion of
the Universe
for
relativistic matter or
matter coupled to radiation
(ionized, plasma)
Vs ~ C

16. Structure Formation in the Universe
structure growth (growth of d) only if
=>
expansion of
the Universe
for
relativistic matter or
matter coupled to radiation
(ionized, plasma)
Vs ~ C
no structure
growth at all
horizon ct t

17. Structure Formation in the Universe
structure growth (growth of d) only if
=>
expansion of
the Universe
no structure
growth at all
horizon ct
Universe cools down
when kT< mc2 or
gas gets neutral
only then
structure growth
can start
when pressure term
disappears t

18. Structure Formation in the Universe
no structure growth
before (re)-combination p + e- => H + g (comsic microwave background)
as long as particles are relativistic kT > mc2 d
pressure
vanishes t
(re) combination , CMB

19. since (re)combination
Structure Formation in the Universe
in a matter dominated Universe
plug in R ~ t 2/3
Ansatz d ~ t n
d ~ t 2/3
density contrast grows
like the scale factor
d ~ R
d x 1100
since (re)combination
taking into account the expansion of the Universe
R: scalefactor
if defined =1 today, was 1/1000 at (re)combination)

20. particles without electromagnetic interaction
observed anisotropy of 10-5 by far too small
10-5
x 1100
10-2
???
was there a 100 x larger anisotropy we cannot see in the CMB ?
if yes, then made out of
particles without electromagnetic interaction
otherewise we would see it in CMB
Dark Matter

21. Neutrinos there are 336 neutrinos / cm-3 left from Big Bang
could be a considerable contribution to Dark Matter
100% of dark matter if
~ 10 eV

22. Structure Formation in the Universed
(re) combination , CMB
Baryons (p,n,e-, H, He)
Dark Matter
the only non electromagnetic particles in the standard model are Neutrinos
BUT: Neutrinos still relativistic at (re)combination ( kT ~ 0,3 eV )
cannot form structure
too big
dark matter is not made out of (light) neutrinos / hot dark matter
we need cold dark matter or at least warm dark matter (> ~ keV mass)

23. Neutrinos there are 336 neutrinos / cm-3 left from Big Bang
could be a considerable contribution to Dark Matter
100% of dark matter if
~ 10 eV
but: they are too light
look at structure in the Universe to get limits on

24. Structure Formation in the Universe
too big
the relic neutrino density is given
as heavier the light neutrinos are
as larger their contribution
to hot dark matter
small scale structures are supressed

25. Neutrinos Wn
mni
limits on

26. Structure Formation in the Universed
(re) combination , CMB
Baryons (p,n,e-, H, He)
Dark Matter
can we see this dark matter ?
yes

27. compression
peaks stronger
expansion
peaks weaker
charged particles (p, e-) oscillate in a background non-oscillating gravity field
made from neutral particles, which started structure formation much earlier

28. compression
peaks stronger
expansion
peaks weaker
charged particles (p, e-) oscillate in a background non-oscillating gravity field
made from neutral particles, which started structure formation much earlier

29. ? ? ? ? p u d e- ne new particles beyond the standard model WIMP
weakly interacting
heavy ( > ~ keV)
many ideas :
sterile keV neutrinos
Axions
Supersymmetry ….
100 GeV - ~ 1000 GeV
mass range is “quite natural“
accelerator bounds
thermodynamics during big bang
or ~ 5GeV
if it shares matter-antimatter asymmetry
( mc ~ WDM / Wp,n ) ? u p ? d ? e- ne ?
WIMP
weakly interacting massive particle
new particles
beyond the standard model

30. Direct Dark Matter Search – (near) future
CRESST
1t scale liquid Xenon
detectors running
XENON 1t
LZ coming
Cryogenics:
EDELWEISS and
CRESST continue running
SuperCDMS funded
worldwide cooperation
SuperCDMS
XENON 1T
sensitivity at low and high WIMP masses will improve
in case of discovery: good possibilities for multitarget confirmation
might turn into neutrino detection

31. LHC DM Searches remarkable progress x 1000 improvement in sensitivity
in 10 yrs
present best sensitivities
(for spin independent WIMP scattering)
cryogenic
liquid Xenon
+ other techniques
(doing better for spin dependent WIMP scattering)
we have different techniques
with promising sensitivity
simultaneously
LHC is running
and will march upward in mass
spin independent interaction
This is just a summary of what the various sensitivites mean. There are rather few events to be detected at the 10E-10 pb level.
spin dependent interaction

32. Dark Matter and Neutrinos
(re) combination , CMB
Baryons (p,n,e-, H, He)
Dark Matter
there are 336 neutrinos / cm-3 left from Big Bang
could be a considerable contribution to Dark Matter
CMB anisotropy observations and structure formation
show Dark Matter is
non-electromagnetic
non-relativistic long before (re)combiantion
mass >~ keV
study of large scale structure allows to set limits on
direct search 0.1 GeV to ~ 1000 GeV
This is just a summary of what the various sensitivites mean. There are rather few events to be detected at the 10E-10 pb level.