Transcript Slide 1

Searches for Particle Dark
Matter - status
Jan Conrad
Gamma 2012
Oskar Klein Centre
July 9-13, 2012
Physics Department
Heidelberg
Stockholm University
[email protected]
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Who has never heard of this?
70%
25 %
2
Weakly Interacting Massive Particles (WIMPs)
The weak interaction mass scale and ordinary gauge
couplings give right relic DM density without fine-tuning.
Mass scale O(GeV)-O(TeV), makes them Cold Dark Matter
Wimp
1026 cm3 s 1

v
v ~ weak ~
2
2
WIMP
m
 26
~ 10
3 1
cm s
Jungman+, Phys. Rept. (1996)
Will not talk about axions1, WISPs (sub-eV), sterile neutrinos (keV)
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Detection of Dark Matter
Indirect detection rate = (particle physics part) ×
(astrophysical part)
X-section
Yield
v  Y ( E )
PPP 
m2
APP   ddl  2 (l )
DM density
WIMP mass
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Universal signatures Y(E)
  ...  p 0  gg
Birkedal et al.,
Ullio et al. Phys.Rev.D66:123502,2002
  Z,gg
Bringmann et al. JHEP 0801:049,2008.
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APP- halo density profile
Cosmological
N-body
simulations:
 NFW (r ) 
c
r (a  r ) 2
Einasto (r )  exp( Ar )
NavarroFrenk-White
Einasto
 ”Cuspy”
Stellar
dynamics:
 Bur ker t (r ) 
c
(r  a)(a 2  r 2 )
We are
here
e.g. Burkert.
 ”Cored”
R. Catena
Strongest signal from the Galactic Center !
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APP- ´substructure
We are here
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Targets and publications (incomplete)
Galactic
Centre
Fermi-LAT: TeVPA 2009, arXiv:0912.3828
Fermi: Goodenough & Hooper, arXiv:0910.2998
Fermi: Dobler et al., arXiv:0910.4583
Dwarf
galaxies
and
Galaxy
Clusters
Fermi-LAT: Phys. Rev. Lett. 107, 241302 (2011)
H.E.S.S.: Astropart.Phys. 34 (2011) 608-616
MAGIC: Astrophys.J. 697 (2009) 1299-1304
VERITAS: Astrophys.J. 720 (2010) 1174-1180 .
VERITAS: Phys.Rev.D85:062001,2012
Galactic
Halo
H.E.S.S. Phys.Rev.Lett. 106 (2011) 161301
Fermi: Cirelli et. al. arXIv: 0912.0663
Fermi-LAT: arXiv: 1205.6474
Extra
Galactic
Fermi-LAT: JCAP 1004:014,2010
Fermi: Akorvazian et. al.arXiv:1002.3820
Fermi : Huetsi et. al. arXiv:1004.2036
Lines
Fermi-LAT: Phys.Rev.Lett.104:091302,2010
Fermi: Vertongen et al. JCAP 1105 (2011) 027
Fermi: Weniger et al. arXiv:1204.2797
Fermi: Bringmann et al. arXiv:1203.1312
Fermi-LAT: 1205.2739, Phys.Rev.D.
HESS: see v. Eldik talk later today
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Targets - comments
Galactic
Centre
Strongest signal expected, most difficult background
Hard sources, not well understood diffuse emission
Dwarf
galaxies
and
Galaxy
Clusters
Dwarfs: weak signal, but relatively well controlled Dark
Matter Distribution and essentially no background (if at
high latitude).
Clusters: DM density not well constrained, but provides
boost factor (extended emission), so good for discovery (if
lucky)
Galactic
Halo
Fermi-LAT: spatial and spectral discrimination, good
statititstics, extreme freedom in galactic diffuse emission.
IACT: best potential, small systematics due to diffuse
emission, ~100 hour observation time (GC halo)
Extra
Galactic
Very model dependent, good as target for spatial analysis.
Lines
Smoking gun*, got to get lucky.
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Dwarfs galaxies – cleanest target
•
•
•
•
DM dominated (M/L ~10--1000).
Nearby (~ 100 kpc)
Low background but relatively small signal
Stellar velocities can be used to measure DM density (error
can be propagated to particle constraints)
e.g:
Charbonnier+, MNRAS 418 (2011)
1526
Strigari+,Phys. Rev. D, 75, 083526
Evans+, Phys. Rev., D69, 123501,
(2004)
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Dwarf galaxies probed in gamma-rays
Fermi
H.E.S.S.
MAGIC
Veritas
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Analysis details
Fermi
Exposure
Background
(hours)
modeling
11 month,
Diffuse/
24 month
Point sources
DM distribution
Empirical NFW
(~ 1500 h)
H.E.S.S.
~15
On-off
Empirical NFW
Theo. NFW
VERITAS
~15
On-off
~50 (Segue)
MAGIC
~15
Empirical NFW
Empirical Einasto
On-off
Empir. NFW
Empir. core/cusp
Kazantzidis
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The Fermi-LAT dwarf analysis
(maximum likelihood)
Two new methodological approaches:
• Combining single source likelihoods  less sensitive to
individual source fluctuations, improved constraints, but
analysis can be optimized individually
• 1) Including uncertainties in DM density
Applied to a the combination  over-all result is much less
affected by the DM density uncertainties (impact reduced by
factor 10).
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Dwarf constraints -status
χχ  qq
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Galactic diffuse emission: Best shot for Air
Cherenkov telescopes
 Large signal (shape and spectrum)
 Large background
 Very complicated background for the Fermi-LAT
However see: Fermi-LAT: arXiv: 1205.6474
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H.E.S.S. Galactic Center Halo
• Galactic center is observed anyway
• 112 hours of GC observations
• Little diffuse background, sensitive to
gradients “only”
BG
Signal
5 deg
Signal
BG
LAT
Draco
11
month
Abramowski et al, PRL 106 (2011) 161301
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Gamma-ray constraints, present status
χχ  qq
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Future: Cherenkov Telescope Array
• Right now: optimization of array configuration
• DM targets studied in upcoming paper:
–
–
–
–
Galactic Centre Halo
Dwarf Galaxies
Clusters of Galaxies
Spatial signal/Axions
… under review by Astroparticle Physics, to appear very
soon …
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Gamma-ray constraints – with CTA
Doro+ (CTA Consort), Astroparticle Physics .
On CTA: see W. Hofmann tomorrow.
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DMA
Presentday limit
Next
generation
limit
Direct detection cross section (pb)
Direct detection, neutrinos (Sun)
Complementarity (Direct/Indirect)
CTA
FERMI
pMSSM
Some LHC detectable
Gamma-ray flux
Gamma-rays
Bringmann+, Phys.Rev. D83 (2011) 045024
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Complementarity with LHC
pMSSM (benchmark from coannihilation region)
LHC
solution:
NOT DM
LHC
solution:
DM
Empty contours: LHC only
Gaugino
masses
Excluded
with FermiLAT dwarf
limit
Bertone+,Phys.Rev. D85 (2012) 055014
Filled: Including Fermi
dSph Result
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”Detections”
GeV WIMPs
~
MeV WIMPs
~
TeV WIMPs
~
From Bergström, Ann.Phys. (Berlin) 524, (2012)
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A line in Fermi-LAT data?
• 3.3σ trial corrected (~50 events)
Bringmann+, arXiv:1203.1312
Weniger arXiv:1204.2797
• 5σ trial corrected
Su&Finkbeiner, arXiv:1206.1616
also:Boyarski+, arXiv:1205.4700
Tempel+, arXiv:1205.4882 (4.5σ)
Weniger xsec
Fermi-LAT (2 year), arXiv:1205.2739
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Questions to be answered before booking the trip to
Stockholm
• Is it instrumental, a fluke or physics?
– What is the (sufficiently strong) line signal in the Fermi-LAT Earth Limb
emission (ZENITH>60, 0 < THETA< 60), at the same energy?
– Can a GC hard source in connection with point spread function modelling
cause this effect?
• If it is physics, is it dark matter?
– Why do Su+Finkbeiner find an offset?
– Can it be a non-line spectral feature? Profumo+, arXiv: 1204.6047
– Can other physical processes except DM produce the feature?
Aharonian+, arXiv:1207.0458
Future interesting high resolution instruments: GAMMA-400 (2018),
DAMPE (China) (2015) , large area instrument HESS II, (see Weniger’s
talk later today).
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Final remarks and summary
• Most robust gamma-ray searches …..
– Dwarf spheroidal galaxies: Fermi-LAT
– Galactic Center halo (H.E.S.S.).
• Gamma-ray searches have constrained the benchmark crosssection of ~10-26 cm-3 s, for WIMPs < 30 GeV, with a
robust and clean method .
• … at the same time yielding ”indications” worth to explore
experimentally (not quite theoretically yet) ….
• Orthogonality to direct/neutrinos and LHC in the most
commonly studied theoretical scenarios (Supersymmetry).
– acc: LHC results, direct: Xenon 1t, IceCube results ..
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Future
• In 2019: CTA/Fermi-LAT constrain thermal WIMP x-sec
from 10 GeV – 10 TeV.  Endgame for the WIMP?
• … unless of course we get lucky …
–
nature picks a model with large line cross-section  Galactic
Centre
• New players: Gamma-400 (2018), DAMPE (2015), HESSII ?
– nature introduces large enough substructure boost in clusters of
galaxies  Galactic clusters
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• Backup
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Summary of line emission constraints
UX1 lines
IDM lines
Mambrini, JCAP 0912:005,2009
Gustafsson et al, PRL,99:041301,2007
Weniger line
Fermi
HESS
GC (binned)
100 h
MSSM
EGRET
GC (binned)
EGRET: Pullen at al, Phys.Rev.D76:063006,2007
H.E.S.S: Ripken, PhD thesis, Hamburg U.
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ATLAS mono-jet results
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Apropos LHC … what about the Higgs?
• no general statements possible ..
• .. well, what is it? (spin 0, couplings to other particles ~ mass),
consistent with SM Higgs or not?
– Large gamma-gamma decay rate might indicate a contribution from
BSM particles
Buckley+, arXiv:1207.1445
• Implication studied in certain contexts of SUSY:
– mSUGRA: implies rather small direct detection x-sec  detectable by
Xenon-1t
Akula+, arXiv:1207.1839
• If line indication correct: annihilation with Higgs  Dirac
Dark Matter
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