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Kashiwa Symposium Lars Bergström, [email protected]
Lars Lars BergstrBergströömmDepartment of PhysicsDepartment of PhysicsStockholm UniversityStockholm University
Kashiwa Symposium Lars Bergström, [email protected]
110
329222
0
100
/1088.18
3
−−
−
≡
⋅==
≡Ω
MpcskmHh
cmghmH Plcrit
crit
ii
πρ
ρρ
Basic facts:
Observations give 0.6 < h < 0.8
Big Bang nucleosynthesis and cosmic microwave background determine baryon contribution ΩBh2 ≈ 0.02.
Ωlum ≈ (4 ± 2) . 10-3 (stars, gas, dust) =>baryonic dark matter has to exist (maybe as warm intergalactic gas?)
But, if ΩM > 0.06, there has to exist non-baryonic dark matter!
K.M. Nollet, 2002
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Kashiwa Symposium Lars Bergström, [email protected]
Combined fit using CBI data (J.L. Sievers et al., astro-ph/0205387)
Including LSS
2hCDMc Ω≡ω
Kashiwa Symposium Lars Bergström, [email protected]
New results from DASI (September 19, 2002): Polarisation detected at > 5σ. TE cross-correlation (2-3σ) agrees perfectly with prediction of Concordance Model, ΛCDM (ΩM = 0.3, ΩΛ = 0.7)
DASI team, J. Carlstrom et al. DASI team, J. Carlstrom et al.
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Kashiwa Symposium Lars Bergström, [email protected]
Large-scale structure is in striking agreement with the Concordance Model,
ΛCDM (ΩM = 0.3, ΩΛ = 0.7)
P. Norberg & S. Cole, 2000
Kashiwa Symposium Lars Bergström, [email protected]
Cold Dark Matter
• Part of the “Concordance Model”• Gives excellent description of large scale structure, Ly-α
forest, gravitational lensing• If consisting of particles, may be related to electroweak mass
scale: weak cross section, non-dissipative WIMPs. Potentially detectable, directly or indirectly.
• May or may not describe small-scale structure in galaxies: Controversial issue, but alternatives (self-interacting DM, warm DM, self-annihilating DM) seem worse.
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Kashiwa Symposium Lars Bergström, [email protected]
N-body simulations by Ben Moore, http://www.nbody.net
Too many subhalos in CDM? Maybe dark! Gravitational lensing may need subhalos (Dalal & Kochanek, 2002)
CDM radial profile too singular? Observations unclear; baryonic feedback not included in simulations
Simulation of self-interacting dark matter halo - excluded by lensing
Kashiwa Symposium Lars Bergström, [email protected]
Ben Moore, www.nbody.net
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Kashiwa Symposium Lars Bergström, [email protected]
’Milky Way’simulation
Helmi, White & Springel, 2002
Kashiwa Symposium Lars Bergström, [email protected]
de Blok and Bosma 2002:
Rotation curves of low surface brightness galaxies not well fit by CDM?
de Blok and Bosma 2002:
Rotation curves of low surface brightness galaxies not well fit by CDM?
astro-ph/0201276
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Kashiwa Symposium Lars Bergström, [email protected]
soft core1/r (CDM)
Elliptical galaxy NGC 4636, Chandra X-ray image
CHANDRA LIMITS ON NATURE OF DARK MATTER. Dark matter distribution seems highly concentrated, in agreement with CDM. Self-interacting dark matter ruled out? (Loewenstein andMushotzky, astro-ph/0205359)
New Chandra results on cluster A2029: perfect fit to CDM, cored model ruled out (astro-ph/0209205).
Kashiwa Symposium Lars Bergström, [email protected]
ΩM ~ 0.3 in Concordance Model instead of ΩM ~ 1 in the ”Standard CDM” of the 1980’s→ Good news for dark matter searches!Explanation: ΩDM ~ 1/(σannv)Crossing symmetry ⇒ σscatt ~ σannThus, low ΩDM (if enough to make up galaxy halos) means higher annihilation & scattering rates
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Kashiwa Symposium Lars Bergström, [email protected]
Supersymmetry• Invented in the 1970’s• Necessary in most string theories• Restores unification of couplings• Solves hierarchy problem• Gives right scale for neutrino masses• Predicts light Higgs ( < 130 GeV)• May be detected at Fermilab/LHC• Gives an excellent dark matter candidate (If R-parity is
conserved)• Useful as a template for generic “WIMP” (Weakly
Interacting Massive Particle)
Kashiwa Symposium Lars Bergström, [email protected]
MSSM – Minimal Supersymmetric extension of the Standard Model
R parity conservation (multiplicative quantum number) gives naturaldark matter candidate
• The simplest supersymmetric extension of the Standard Model. Only one supersymmetry generator (N = 1 SUSY) ⇒ one superpartner to each SM particle.
• 2 Higgs doublets required ⇒ 5 physical Higgs bosons.
• Allow most general soft SUSY-breaking terms, preserving R-parity:
The most general R-parity conserving lagrangian has 124 free parameters!We reduce to 7 parameters:µ: Higgsino mass parameterΜ2: Gaugino mass parametertanβ: ratio of Higgs vevsM3: Mass of pseudoscalar Higgs bosonM0 : scalar mass parameterAb, At: Soft trilinear parameters
( ) ( ) SLBR 231 +−−=sparticlesfor 1particlesfor 1
−+
=R⇒
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Kashiwa Symposium Lars Bergström, [email protected]
024
013
021
0 ~~~~~ HaHaZaa +++= γχMost plausible SUSY dark matter candidate: The lightest neutralino
fraction higgsino)1(||||
fraction gaugino||||
;1||
24
23
22
21
4
1
2
gh
g
ii
ZZaa
Zaa
a
−=≡+
≡+
=∑=
Neutralinos are Majorana particles (their own antiparticles).
,...,,,~~ 03
02,1
0000 HHZZWWff −+→+ χχTree-level annihilation:
( )( ) 200
00
3
0
3
~~helicity todue and forbidden, is~~
property, Majorana todue However,
dominate. should wave-Shalos galactic in110
fS
S
mff
cv
∝→
⇒<<≈ −
χχ
χχ
Kashiwa Symposium Lars Bergström, [email protected]
Prime candidate: MSSM χ, thermally produced in the early Universe However, there are other possibilities for Dark Matter related to supersymmetry:
• , sneutrinos (Hall & Murayama, …)
• ã, axinos (Kim & Roszkowski, …)
• Wimpzillas (Kolb & al) – superheavy relics
• Cryptons (J. Ellis & al) – superheavy relics
• Q-balls (Kusenko & al,..), Q → χ (non-thermal)
• Self-interacting DM (Spergel & Steinhardt)?
χ DM useful template for generic Weakly Interacting Massive Particle (WIMP) – also non-supersymmetric ones
ν~
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Kashiwa Symposium Lars Bergström, [email protected]
Model for Neutralino Galactic Halo:
ρlocal ∼ 0.3 GeV/cm3, v/c ∼ 10-3, mχ ∼ 100 GeV
⇒ flux 103 cm-2 s-1 sr-1 !
Kashiwa Symposium Lars Bergström, [email protected]
Usually, the heaviest kinematically allowed final state dominates (b or t quarks; W & Z bosons)
Note: equal amounts of matter and antimatter in annihilations - source of antimatter in cosmic rays?
Decays from neutral pions:Dominant source of continuum gammas in halo annihilations
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Kashiwa Symposium Lars Bergström, [email protected]
Loop-induced 2γ (or Zγ) final state: source of nearly monoenergetic photons
L.B. & P. Ullio, 1998
v/c ≈ 10-3 ⇒
or
(for Zγ)
)4
1( 2
2
χγγ m
mmE Z−≈χγ mE ≈
Rates are generally large (B.R. ∝ 10-3 - 10-2) for higgsino-like neutralinos (in particular, also for TeV-scale higgsinos)
Kashiwa Symposium Lars Bergström, [email protected]
Paolo Gondolo, Joakim Edsjö, Lars Bergström,Piero Ullio and Edward A. Baltz
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Kashiwa Symposium Lars Bergström, [email protected]
Release / download
• Major code reorganization to make it user-friendly.• Tested on RedHat Linux 7.3, LinuxPPC, MacOS X and Alphas.• Released now as a fully working beta-version.• Full release in autumn of 2002 with manual and long paper.• Download at http://www.physto.se/~edsjo/darksusy/• If you use it, please sign up on the DarkSUSY mailing list on that
page!
Kashiwa Symposium Lars Bergström, [email protected]
Methods of SUSY Dark Matter detection:
• Discovery at accelerators (Tevatron II, LHC,..)
• Direct detection of halo particles
• Indirect detection of neutrinos, gamma rays, radio waves, antiprotons, positrons
The basic process for indirect detection is annihilation:
χχ
Neutralinos are Majorana particles
vnann σχ2∝Γ Enhanced for
clumpy halo; near galactic centre and in Sun & Earth
χ χq
e+ν
γ
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Kashiwa Symposium Lars Bergström, [email protected]
Direct ”detection” by DAMA – controversial issue
Kashiwa Symposium Lars Bergström, [email protected]
New EDELWEISS results (June, 2002)
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Kashiwa Symposium Lars Bergström, [email protected]
New ZEPLIN I limit
N. Smith, IDM2002, York
DAMA seems completely ruled out! (However, if the halo has a more complicated DM structure with clumps and streams, this need not be so. See A.M. Green, 2002.)
Preliminary
Kashiwa Symposium Lars Bergström, [email protected]
γ line, χχ→γγmχ = 50 GeV
mχ = 300 GeV
continuous γ
L.B., P.Ullio & J. Buckley 1998
Advantage of gamma rays: point back to the source. Enhanced flux possible thanks to substructure (as predicted by CDM)
Indirect detectionthrough γ-rays. Two types of signal: continuous (large rate but at lower energies, difficult signature) and monoenergetic line(small rate but at highest energy Eγ = mχ; ”smoking gun”).
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Kashiwa Symposium Lars Bergström, [email protected]
USA-France-Italy-Sweden-Japan (-Germany) collaboration, launch 2006
GLAST will also likely detect a few thousand new GeV blazars …
Kashiwa Symposium Lars Bergström, [email protected]
DarkSUSY: Gammas from the halo
• The flux in a given direction (averaged or not averaged over detector resolution ∆Ω) can be obtained for– continuum gamma rays– monochromatic gamma lines from γγ– monochromatic gamma lines from Zγ
• Both differential and integrated fluxes can be obtained.
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Kashiwa Symposium Lars Bergström, [email protected]
L.B., J. Edsjö and C. Gunnarsson, 2000
∫∫
Ω
∆Ω≡∆Ω=
∆Ω⋅∝∆ΩΦ
...
2
32 /3.0)(
)5.8(1);ˆ(;
);;ˆ();ˆ(
sol cmGeVr
kpcdldnJ
mvN
S
nJSnrρσ
χ
γ
γ
Note models extending to TeV mass range
Kashiwa Symposium Lars Bergström, [email protected]
Possible observable γ-ray sources of Dark Matterannihilation
• Diffuse emission from Milky Way dark matter halo (maybe indicated by EGRET data? Dixon et al. 1997; ”GeV excess”;…)
• Excess emission from Galactic Center (maybe indicated by EGRET data? Meyer-Hasselwander et al. 1997; Bertone, Sigl, Silk 2001)
• Other nearby galaxies (M31, M87, …)
• Dwarf galaxies (Draco, Ursa Minor, Sagittarius, …)
• Globular clusters (? Omega Centauri; J. Guy et al 2002)
• Galaxy clusters
• Halo DM clumps without optical counterparts (”unidentifiedEGRET sources”?)
• Diffuse extragalactic signal from all cosmic DM structure
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Kashiwa Symposium Lars Bergström, [email protected]
Major uncertainty for gamma-ray detection from galactic center: Halo dark matter density distribution.
;)(
;)(
;))((
)(
;)(
)(
;)(
)(
2SIS
22CIS
22Burkert
2NFW
2/32/32/3Moore
rcr
racr
raarcr
rarcr
rarcr
=
+=
++=
+=
+=
ρ
ρ
ρ
ρ
ρFits to N-body simulations
Fits to rotation curves
Fit to lensing (elliptical galaxies)
Kashiwa Symposium Lars Bergström, [email protected]
Note large uncertainty of flux for nearby objects(Milky Way center, LMC, Draco,…)
In this region(at cosmological distances),the uncertainty is much less
2
3/3.0)(
)5.8(1);ˆ( ∫∫
Ω
∆Ω≡∆Ω
cmGeVr
kpcdldnJ
rρ
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Kashiwa Symposium Lars Bergström, [email protected]
Galactic center source – interesting but highly uncertain
Bergström, Ullio, Buckley 1998
Binney and Evans 2001: Microlensing data towards bulge indicate low DM density near center. NFW does not fit ⇒ <J> ≤ 100. However, clumps may enhance by at least factor 10 (also maybe spike from black hole; see later)
Kashiwa Symposium Lars Bergström, [email protected]
CDM simulation of SUSY gamma-ray sky
(Calcaneo-Roldan & Moore, 2000)
L.B., J. Edsjö and C. Gunnarsson, 2000
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Kashiwa Symposium Lars Bergström, [email protected]
”Local group” simulation by B. Moore et al., astro-ph/0106271
Fit to NFW profile
Fit to Moore profile
”Draco”
minihalo
Kashiwa Symposium Lars Bergström, [email protected]
SUSY γ-ray signals from Draco (C. Tyler, astro-ph/0203242)
DarkSUSY points
Unrealistic (?) SIS profile 1/r2
assumed
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Kashiwa Symposium Lars Bergström, [email protected]
With NFW or Moore profile, signal seems difficult to detect
Moore profile
SIS
Kashiwa Symposium Lars Bergström, [email protected]
Tasitsiomi and Olinto, astro-ph/0206040 ”Detectability of neutralino clumps in ACTs”
105 MSun clump (Moore profile) at 61 pc distance
DarkSUSY
Aeff = 108 cm2, 100 hr,σθ = 6´, Eth = 50 GeV
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Kashiwa Symposium Lars Bergström, [email protected]
P.Ullio, L.B., J. Edsjö, C. Lacey, astro-ph/0207125
Maximum distance at which a subclump of given mass can be seen
* Tatsiomis - Olinto
Kashiwa Symposium Lars Bergström, [email protected]
Dark matter cusp at Galactic Centre caused by black hole?
(Gondolo and Silk, 1999)
Very sensitive to merger history of black hole (Kamionkowski, Zhao, Ullio; Nakano & Makino; Merritt & Milosavljevic)
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Kashiwa Symposium Lars Bergström, [email protected]
Bertone, Sigl & Silk, 2001
Simultaneous fit to radio emission (408 MHz) and EGRET γ-ray spectrum possible if halo is mildlysingular ρ(r) ∝ 1/r0.1, enhanced by formation of spike.
Sub-mm bump due to processes in accretion disk?
mχ = 500 GeV
B = Beq
Kashiwa Symposium Lars Bergström, [email protected]
(PRL 87 (2001) 251301)
Idea: Redshifted gamma-ray line gives peculiar energyfeature – may be observable for CDM-type cuspy halos and substructure (cf. Taylor & Silk, 2002)
Enhancement due to substructure
Absorption on IR/opticalbackground
Cosmology
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Kashiwa Symposium Lars Bergström, [email protected]
No data in this region (GLAST will cover it)
Kashiwa Symposium Lars Bergström, [email protected]
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Kashiwa Symposium Lars Bergström, [email protected]
Structure may enlarge the annihilation signal by factor 105 – 106!
Eke, Navarro, Steinmetz
Kashiwa Symposium Lars Bergström, [email protected]
Estimating the extragalactic background - blazars
Many uncertainties: • spectral index & redshift distribution• intrinsic absorption & energy cut-off• cascading not included• has EGRET isolated the true extragalactic signal?
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Kashiwa Symposium Lars Bergström, [email protected]
Points should move down as GLAST resolves more blazars
Kashiwa Symposium Lars Bergström, [email protected]
Note: In models with nonthermal production of neutralinos, annihilation rates can be up to 2 orders of magnitude higher!
Ullio (1999); Fujii and Hamaguchi hep-ph/0205044
MSSM
AMSB
Fujii & Hamaguchi
Fujii & Hamaguchi
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Kashiwa Symposium Lars Bergström, [email protected]
Range of predictions for anomaly-mediated SUSY breaking models
GLAST sensitivity curve including halo substructure
Upper rangeof MSSM predictions
Kashiwa Symposium Lars Bergström, [email protected]
New muon g-2 measurement presented Aug. 1, 2002:
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Kashiwa Symposium Lars Bergström, [email protected]
E.A. Baltz & P. Gondolo, astro-ph/0207673:
Kashiwa Symposium Lars Bergström, [email protected]
All modelsg-2 constraint
g-2 result, if due to SUSY, selects models with high continuum gamma rate and low mass
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Kashiwa Symposium Lars Bergström, [email protected]
Note complementarity between direct and gamma-ray detection!
Kashiwa Symposium Lars Bergström, [email protected]
Indirect detection through neutralino capture and annihilation at the centre of the Earth or the Sun. However, Earth rates and direct detection rates are strongly correlated ⇒neutrinos not competitive with new DM direct detection experiments
Other indirect detection methods(often complementary to γ-rays)
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Kashiwa Symposium Lars Bergström, [email protected]
Antiprotons at low energy can not be produced in pp collisions in the galaxy, so that may be DM signal?
However, p-He reactions and energy losses due to scattering of antiprotons ⇒ low –energy gap is filled in.
BESS data compatible with conventional production by cosmic rays
L.B., J. Edsjö and P. Ullio, 1999
Kashiwa Symposium Lars Bergström, [email protected]
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Kashiwa Symposium Lars Bergström, [email protected]
Positrons from neutralino annihilations – explanation of
feature at 10 – 30 GeV?
Kashiwa Symposium Lars Bergström, [email protected]
Possible signature in CMBR and radio background? (Blasi, Olinto & Tyler, astro-ph/0202049)
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Kashiwa Symposium Lars Bergström, [email protected]
”Benchmarks”: use small number of ”well-motivated” points in SUSY parameter space (Snowmass 2001)
CRESST & CDMS II projected limits GENIUS
Direct detection
Kashiwa Symposium Lars Bergström, [email protected]
Neutrinos
Gamma-rays
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Kashiwa Symposium Lars Bergström, [email protected]
Conclusions
• Existence of dark matter more certain than ever• CDM seems favoured• Supersymmetric particles (neutralinos) are among the best-
motivated candidates• Detection in γ-rays seems very promising if current ideas
about structure and substructure formation are correct• However, expected rates are uncertain due to unknown
details of particle physics parameters and actual halo structure
• Gamma-ray detection complementary to other direct and indirect detection methods
• New generation of γ-ray detectors have great potential to observe - or limit - dark matter: please help in the search!
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