Indirect Dark Matter Searches Torsten Bringmann, University of - PowerPoint PPT Presentation

Gamma-ray flux The expected gamma-ray flux [GeV -1 cm -2 s -1 sr -1 ] from a source with DM density is given by ρ dN f ( E γ , ∆ ψ ) = � σ v � ann d Φ γ d Ω � � γ � d ℓ ( ψ ) ρ 2 ( r ) B f · 8 π m 2 ∆ ψ dE γ dE γ ∆ ψ l . o . s χ f particle physics astrophysics : total annihilation cross section for point-like sources: � σ v � ann � − 1 � D 2 ∆ ψ d 3 r ρ 2 ( r ) � : WIMP mass ≃ (50 GeV � m χ � 5 TeV) m χ : branching ratio into channel B f f ∆ ψ : angular res. of detector : number of photons per ann. D : distance to source N f γ ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 9

Gamma-ray flux The expected gamma-ray flux [GeV -1 cm -2 s -1 sr -1 ] from a source with DM density is given by ρ dN f ( E γ , ∆ ψ ) = � σ v � ann d Φ γ d Ω � � γ � d ℓ ( ψ ) ρ 2 ( r ) B f · 8 π m 2 ∆ ψ dE γ dE γ ∆ ψ l . o . s χ f particle physics astrophysics : total annihilation cross section for point-like sources: � σ v � ann � − 1 � D 2 ∆ ψ d 3 r ρ 2 ( r ) � : WIMP mass ≃ (50 GeV � m χ � 5 TeV) m χ : branching ratio into channel B f f ∆ ψ : angular res. of detector : number of photons per ann. D : distance to source N f γ { high accuracy spectral information ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 9

Gamma-ray flux The expected gamma-ray flux [GeV -1 cm -2 s -1 sr -1 ] from a source with DM density is given by ρ dN f ( E γ , ∆ ψ ) = � σ v � ann d Φ γ d Ω � � γ � d ℓ ( ψ ) ρ 2 ( r ) B f · 8 π m 2 ∆ ψ dE γ dE γ ∆ ψ l . o . s χ f particle physics astrophysics : total annihilation cross section for point-like sources: � σ v � ann � − 1 � D 2 ∆ ψ d 3 r ρ 2 ( r ) � : WIMP mass ≃ (50 GeV � m χ � 5 TeV) m χ : branching ratio into channel B f f ∆ ψ : angular res. of detector : number of photons per ann. D : distance to source N f γ { { high accuracy large uncertainty in spectral information normalization ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 9

Halo profiles CDM N -body simulations Fits to rotation curves? Λ c c ρ NFW = ρ Burkert = ( r + a )( a 2 + r 2 ) r ( a + r ) 2 a [( r a ) α − 1 ] ρ Einasto ( r ) = ρ s e − 2 c ρ iso = ( a 2 + r 2 ) ( α ≈ 0 . 17) conflicting observational claims rather stable result � � (NB: observation of stars) ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 10

Halo profiles CDM N -body simulations Fits to rotation curves? Λ c c ρ NFW = ρ Burkert = ( r + a )( a 2 + r 2 ) r ( a + r ) 2 a [( r a ) α − 1 ] ρ Einasto ( r ) = ρ s e − 2 c ρ iso = ( a 2 + r 2 ) ( α ≈ 0 . 17) conflicting observational claims rather stable result � � (NB: observation of stars) Situation a bit unclear; effect of baryons? see talks by (But could also lead to a steepening of the profile!) C. Frenk & Difference in annihilation flux several orders A. Zentner of magnitude for the galactic center Situation much better for e.g. dwarf galaxies ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 10

Substructure N -body simulations: The DM halo contains not only a smooth component, but a lot of substructure! Indirect detection effectively involves some averaging: Φ SM ∝ � ρ 2 χ � = (1 + BF) � ρ χ � 2 Fig.: Bergström, NJP ’09 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 11

Substructure N -body simulations: The DM halo contains not only a smooth component, but a lot of substructure! Indirect detection effectively involves some averaging: Φ SM ∝ � ρ 2 χ � = (1 + BF) � ρ χ � 2 Fig.: Bergström, NJP ’09 “Boost factor” each decade in M subhalo contributes about the same e.g. Diemand, Kuhlen & Madau, ApJ ’07 important to include realistic value for ! M cut depends on uncertain form of microhalo profile ( ...) and dN/dM c v (large extrapolations necessary!) ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 11

DM annihilation spectra Secondary photons from fragmentation 1000 100 mainly from π 0 → γγ d N γ / d x 10 1 result in a rather featureless, 0 . 1 0 . 01 model-independent spectrum 0 . 001 0 . 02 0 . 05 0 . 1 0 . 2 0 . 5 1 x = E/m χ Bertone et al., astro-ph/0612387 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 12

DM annihilation spectra Secondary photons from fragmentation 1000 100 mainly from π 0 → γγ d N γ / d x 10 1 result in a rather featureless, 0 . 1 0 . 01 model-independent spectrum 0 . 001 0 . 02 0 . 05 0 . 1 0 . 2 0 . 5 1 x = E/m χ Bertone et al., astro-ph/0612387 Line signals from χχ → γγ , γ Z, γ H d Φ / d E γ [10 − 8 m − 2 s − 1 TeV − 1 ] 4 0 . 5% Bergström, Ullio & Buckley, ApJ ’98 3 necessarily loop suppressed: O ( α 2 ) 1% 2 2% smoking-gun signature m B (1) = 800 GeV 1 (energy resolution as indicated) 0 . 78 0 . 78 0 . 79 0 . 80 0 . 81 E γ [TeV] Bergström, TB, Eriksson & Gustafsson, JCAP ’05 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 12

DM annihilation spectra Secondary photons from fragmentation 1000 100 mainly from π 0 → γγ d N γ / d x 10 1 result in a rather featureless, 0 . 1 0 . 01 model-independent spectrum 0 . 001 0 . 02 0 . 05 0 . 1 0 . 2 0 . 5 1 x = E/m χ Bertone et al., astro-ph/0612387 Line signals from χχ → γγ , γ Z, γ H d Φ / d E γ [10 − 8 m − 2 s − 1 TeV − 1 ] 4 0 . 5% Bergström, Ullio & Buckley, ApJ ’98 3 necessarily loop suppressed: O ( α 2 ) 1% 2 2% smoking-gun signature m B (1) = 800 GeV 1 (energy resolution as indicated) 0 . 78 0 . 78 0 . 79 0 . 80 0 . 81 E γ [TeV] Internal bremsstrahlung (IB) Bergström, TB, Eriksson & Gustafsson, JCAP ’05 whenever charged final states are present: O ( α ) characteristic signature (details model-dependent!) usually dominant at high energies Birkedal, Matchev, Perelstein & Spray, hep-ph/0507194 TB, Bergström & Edsjö, JHEP ’08 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 12

mSUGRA spectra focus point region ( m χ = 1926 GeV) bulk region ( m χ = 141 GeV) 1 1 Total BM4 Total I’ Secondary gammas Secondary gammas Internal Bremsstrahlung Internal Bremsstrahlung x 2 dN γ , tot /dx 0.1 x 2 dN γ , tot /dx 0 . 1 0.01 0 . 01 0 . 001 0 . 4 0 . 6 0 . 8 0.2 1 0 . 4 0 . 6 0 . 8 1 0.2 x = E γ /m χ x = E γ /m χ . coannihilation region ( m χ = 233 GeV) funnel region ( m χ = 565 GeV) 1 10 BM3 Total Total K’ Secondary gammas Internal Bremsstrahlung Secondary gammas 1 Internal Bremsstrahlung x 2 dN γ , tot /dx x 2 dN γ , tot /dx 0 . 1 0.1 0.01 0 . 01 0 . 001 0 . 4 0 . 6 0 . 8 0.2 1 0 . 4 0 . 6 0 . 8 1 0.2 x = E γ /m χ x = E γ /m χ . (benchmarks taken from TB, Edsjö & Bergström, JHEP ’08 and Battaglia et al., EPJC ’03) ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 13

Comparing DM spectra (Very) pronounced cut-off at E γ = m χ Further features at slightly lower energies Could be used to distinguish DM candidates! Example: mSUGRA benchmarks (assume energy resolution of 10%) ) 0 0 3 2 ( 1 n o i t a l i h i n n a o c x 2 dN/dx – BM4 – focus point (10.9) 0.1 3 M B I ’ 0.01 – b u K l ’ k – f u ( n 3 n e . l 6 ) 0.001 0.2 0.4 0.6 0.8 1.0 1.2 x = E γ /m χ TB, PoS ’08 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 14

Comparing DM spectra (Very) pronounced cut-off at E γ = m χ Further features at slightly lower energies Could be used to distinguish DM candidates! Example: Higgsino vs KK-DM (about same mass; assume ) ∆ E = 15% 10 3 γ d( σv ) γ / d E γ [10 − 29 cm 3 s − 1 TeV] B (1) 10 2 Higgsino E 2 10 0 . 1 0 . 5 1 2 E γ [TeV] Bergström et al. , ’06 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 14

IB: total flux enhancement IB contributions important at high energies � this is where Air Cherenkov Telescopes are most sensitive! ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 15

IB: total flux enhancement IB contributions important at high energies � this is where Air Cherenkov Telescopes are most sensitive! Example: Dwarf galaxies ∆ E/E = 10% IB boosts effective sensitivity by a factor of up to ~10 TB, Doro & Fornasa, JCAP ’09 Cannoni et al., PRD ’10 CTA could see a DM signal from Willman 1 for a large class of models (less optimistic prospects for Draco) TB, Doro & Fornasa, JCAP ’09 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 15

IB: total flux enhancement IB contributions important at high energies � this is where Air Cherenkov Telescopes are most sensitive! Example: Dwarf galaxies ∆ E/E = 10% IB boosts effective sensitivity by a factor of up to ~10 TB, Doro & Fornasa, JCAP ’09 Cannoni et al., PRD ’10 CTA could see a DM signal from Willman 1 for a large class of models (less optimistic prospects for Draco) important to include also for other targets! TB, Doro & Fornasa, JCAP ’09 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 15

Where to look Diemand, Kuhlen & Madau, ApJ ’07 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 16

Where to look Diemand, Kuhlen & Madau, ApJ ’07 Galactic center brightest DM source in sky large background contributions ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 16

Where to look Diemand, Kuhlen & Madau, ApJ ’07 Galactic halo good statistics, angular information galactic backgrounds? Galactic center brightest DM source in sky large background contributions ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 16

Where to look Diemand, Kuhlen & Madau, ApJ ’07 Galactic halo good statistics, angular information galactic backgrounds? Dwarf Galaxies DM dominated, M/L~1000 fluxes soon in reach! Galactic center brightest DM source in sky large background contributions ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 16

Where to look Diemand, Kuhlen & Madau, ApJ ’07 Galactic halo good statistics, angular information galactic backgrounds? Dwarf Galaxies DM dominated, M/L~1000 fluxes soon in reach! DM clumps Galactic center easy discrimination brightest DM source in sky (once found) large background contributions bright enough? ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 16

Where to look Diemand, Kuhlen & Madau, ApJ ’07 Galactic halo good statistics, angular information galactic backgrounds? Dwarf Galaxies DM dominated, M/L~1000 fluxes soon in reach! Extragalactic background DM clumps DM contribution from all z Galactic center background difficult to model easy discrimination brightest DM source in sky (once found) large background contributions bright enough? ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 16

Where to look Diemand, Kuhlen & Madau, ApJ ’07 Galactic halo good statistics, angular information galactic backgrounds? Galaxy clusters cosmic ray contamination better in multi-wavelength? Dwarf Galaxies DM dominated, M/L~1000 fluxes soon in reach! Extragalactic background DM clumps DM contribution from all z Galactic center background difficult to model easy discrimination brightest DM source in sky (once found) large background contributions bright enough? ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 16

Sensitivities Ground-based large eff. Area (~km 2 ) small field of view lower threshold 40 GeV � GLAST (1 yr) 1 C.U. 9 − tel. at 2000 m − 10 10 Integral flux limit [ 1 / (s cm ) ] 41 − tel. system 2 4 large + 85 GLAST (5 yrs) − 11 10 MAGIC 0.001 C.U. MAGIC II stereo − 12 10 VERITAS − 13 10 50 h H.E.S.S. 5 σ − 14 10 10 events 0.01 0.1 1 10 100 Energy [ TeV ] Bernlöhr et al., ’07 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 17

Sensitivities Ground-based Space-borne large eff. Area (~km 2 ) small eff. Area (~m 2 ) small field of view large field of view lower threshold 40 GeV � upper bound on resolvable E γ GLAST (1 yr) 1 C.U. 9 − tel. at 2000 m − 10 10 Integral flux limit [ 1 / (s cm ) ] 41 − tel. system 2 4 large + 85 GLAST (5 yrs) − 11 10 MAGIC 0.001 C.U. MAGIC II Fermi stereo − 12 10 VERITAS − 13 10 50 h H.E.S.S. 5 σ − 14 10 10 events 0.01 0.1 1 10 100 (from the LAT webpage) Energy [ TeV ] Bernlöhr et al., ’07 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 17

Status So far no (unambiguous) DM signals seen… … but indirect searches start to be very competitive! ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 18

Status So far no (unambiguous) DM signals seen… … but indirect searches start to be very competitive! Fermi - Clusters, 1002.2239 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 18

Status So far no (unambiguous) DM signals seen… … but indirect searches start to be very competitive! Fermi - Clusters, 1002.2239 Fermi - line search, 1002.2239 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 18

Status So far no (unambiguous) DM signals seen… … but indirect searches start to be very competitive! Fermi - Clusters, 1002.2239 Fermi - dwarfs, 1001.4531 Fermi - line search, 1002.2239 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 18

Status So far no (unambiguous) DM signals seen… … but indirect searches start to be very competitive! Fermi - Clusters, 1002.2239 Fermi - dwarfs, 1001.4531 Fermi - line search, 1002.2239 VERITAS - dwarfs, 1006.5955 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 18

Status So far no (unambiguous) DM signals seen… … but indirect searches start to be very competitive! Fermi - Clusters, 1002.2239 Fermi - dwarfs, 1001.4531 Fermi - line search, 1002.2239 For more details, see talks by: VERITAS - dwarfs, 1006.5955 S.Murgia, B. Cañadas (Fermi), M. Vivier (VERITAS), ... ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 18

Indirect DM searches " + D M e ! _ p + e D M ! ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 19

Indirect DM searches " + D M e ! _ p + e D M ! Charged cosmic rays: GCRs are confined by galactic magnetic fields After propagation, no directional information is left Also the spectral information tends to get washed out Equal amounts of matter and antimatter focus on antimatter (low backgrounds!) ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 19

Propagation Little known about Galactic magnetic field distribution Random distribution of field inhomogeneities propagation well described by diffusion equation � ∂ψ ∂ t − ∇ · ( D ∇ − v c ) ψ + ∂ ∂ pb loss ψ − ∂ ∂ pK ∂ ∂ p ψ = q source ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 20

Propagation Little known about Galactic magnetic field distribution Random distribution of field inhomogeneities propagation well described by diffusion equation � ∂ψ ∂ t − ∇ · ( D ∇ − v c ) ψ + ∂ ∂ pb loss ψ − ∂ ∂ pK ∂ ∂ p ψ = q source often set to 0 (stationary conf.) ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 20

Propagation Little known about Galactic magnetic field distribution Random distribution of field inhomogeneities propagation well described by diffusion equation � ∂ψ ∂ t − ∇ · ( D ∇ − v c ) ψ + ∂ ∂ pb loss ψ − ∂ ∂ pK ∂ ∂ p ψ = q source often set to 0 (stationary conf.) Diffusion coefficient, usually D ∝ β ( E/q ) δ ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 20

Propagation Little known about Galactic magnetic field distribution Random distribution of field inhomogeneities propagation well described by diffusion equation � ∂ψ ∂ t − ∇ · ( D ∇ − v c ) ψ + ∂ ∂ pb loss ψ − ∂ ∂ pK ∂ ∂ p ψ = q source often set to 0 (stationary conf.) Diffusion coefficient, usually D ∝ β ( E/q ) δ convection ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 20

Propagation Little known about Galactic magnetic field distribution Random distribution of field inhomogeneities propagation well described by diffusion equation � ∂ψ ∂ t − ∇ · ( D ∇ − v c ) ψ + ∂ ∂ pb loss ψ − ∂ ∂ pK ∂ ∂ p ψ = q source often set to 0 (stationary conf.) energy losses Diffusion coefficient, usually D ∝ β ( E/q ) δ convection ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 20

Propagation Little known about Galactic magnetic field distribution Random distribution of field inhomogeneities propagation well described by diffusion equation � ∂ψ ∂ t − ∇ · ( D ∇ − v c ) ψ + ∂ ∂ pb loss ψ − ∂ ∂ pK ∂ ∂ p ψ = q source often set to 0 (stationary conf.) energy losses Diffusion coefficient, diffusive usually D ∝ β ( E/q ) δ reacceleration convection K ∝ v 2 a p 2 /D ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 20

Propagation Little known about Galactic magnetic field distribution Random distribution of field inhomogeneities propagation well described by diffusion equation � ∂ψ ∂ t − ∇ · ( D ∇ − v c ) ψ + ∂ ∂ pb loss ψ − ∂ ∂ pK ∂ ∂ p ψ = q source often set to 0 (stationary conf.) energy Sources losses (primary & Diffusion coefficient, secondary) diffusive usually D ∝ β ( E/q ) δ reacceleration convection K ∝ v 2 a p 2 /D ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 20

Analytical vs. numerical How to solve the diffusion equation? ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 21

Analytical vs. numerical How to solve the diffusion equation? Numerically e.g. 3D possible + any magnetic field model + Strong, Moskalenko, … realistic gas distribution, full energy losses + DRAGON ‒ computations time-consuming Evoli, Gaggero, Grasso & Maccione ‒ “black box” ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 21

Analytical vs. numerical How to solve the diffusion equation? Numerically e.g. 3D possible + any magnetic field model + Strong, Moskalenko, … realistic gas distribution, full energy losses + DRAGON ‒ computations time-consuming Evoli, Gaggero, Grasso & Maccione ‒ “black box” (Semi-)analytically e.g. Donato, Maurin, Salati, Taillet, ... Physical insight from analytic solutions + L � 1kpc fast computations allow to sample + ISM 2 h full parameter space ‒ v c only 2D possible ‒ simplified gas distribution, energy losses R = 20kpc ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 21

E.g. secondary antiprotons Propagation parameters of two-zone ( K 0 , δ , L, v a , v c ) diffusion model strongly constrained by B/C Maurin, Donato, Taillet & Salati, ApJ ’01 This can be used to predict fluxes for other species: TB & Salati, PRD ’07 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 22

E.g. secondary antiprotons Propagation parameters of two-zone ( K 0 , δ , L, v a , v c ) diffusion model strongly constrained by B/C Maurin, Donato, Taillet & Salati, ApJ ’01 This can be used to predict fluxes for other species: excellent agreement � ����� � � � with new data: ������ �� �� � BESSpolar 2004 � �� � � Abe et al. , PRL ’08 � � � � PAMELA 2008 � � Adriani et al. , PRL ’10 � � � � � TB & Salati, PRD ’07 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 22

E.g. secondary antiprotons Propagation parameters of two-zone ( K 0 , δ , L, v a , v c ) diffusion model strongly constrained by B/C Maurin, Donato, Taillet & Salati, ApJ ’01 This can be used to predict fluxes for other species: excellent agreement � ����� � � � with new data: ������ �� �� � BESSpolar 2004 � �� � � Abe et al. , PRL ’08 � � � � PAMELA 2008 � � Adriani et al. , PRL ’10 � � � � � very nice test for underlying diffusion model! TB & Salati, PRD ’07 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 22

Antiprotons Rather straightforward to handle: no significant astrophysical sources for completely diffusion p � 10 GeV E ¯ dominated Uncertainties in flux from ¯ p DM annihilation much larger than for secondaries! ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 23

Antiprotons Rather straightforward to handle: no significant astrophysical sources for completely diffusion p � 10 GeV E ¯ dominated TB & Salati, PRD ’09 Uncertainties in flux from ¯ p DM annihilation much larger than for secondaries! up to ~200 from DM profile ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 23

Antiprotons Rather straightforward to handle: no significant astrophysical sources for completely diffusion p � 10 GeV E ¯ dominated TB & Salati, PRD ’09 Uncertainties in flux from ¯ p DM annihilation much larger than for secondaries! up to ~200 from DM profile up to ~40 from range of propagation parameters compatible with B/C TB & Salati, PRD ’09 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 23

Antiprotons ‒ Cannot be used to discriminate between DM candidates... TB & Salati, PRD ’09 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 24

Antiprotons ‒ Cannot be used to discriminate between DM candidates... + …but are quite efficient in settings constraints! light SUSY DM Bottino et al. , PRD ’98+05 non-standard DM profile proposed by deBoer Bergström et al. , JCAP ’06 DM explanations for the PAMELA excess e + /e − Donato et al. , PRL ’09 “Evidence” for DM seen in Fermi data towards the GC TB & Salati, PRD ’09 TB, 0911.1124 ... ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 24

Positrons Excess in cosmic ray positron data has triggered great excitement: )) - 0.4 (e ! )+ 0.3 + (e 0.2 ! ) / ( + (e ! Positron fraction 0.1 Muller & Tang 1987 MASS 1989 TS93 Adriani et al ., Nature ’09 HEAT94+95 CAPRICE94 (> 500 citations since AMS98 10/08!) HEAT00 0.02 Clem & Evenson 2007 PAMELA 0.01 0.1 1 10 100 Energy (GeV) Are we seeing a DM signal ??? ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 25

SUSY DM and PAMELA Neutralino annihilation helicity suppressed: � σ v � ∝ m 2 ℓ m 2 χ ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 26

SUSY DM and PAMELA Neutralino annihilation helicity suppressed: � σ v � ∝ m 2 α em ℓ m 2 π χ ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 26

SUSY DM and PAMELA Bergstr¨ om, Bringmann & Edsj¨ o (2008) Neutralino annihilation 0 . 2 helicity suppressed: PAMELA HEAT � σ v � ∝ m 2 α em 0 . 1 ℓ m 2 π χ e + / ( e + + e − ) Surprisingly hard 0 . 05 spectra possible if dominates! χχ → e + e − γ first attempt to connect BM5’ ( m χ =132 GeV) 0 . 02 PAMELA to DM BM3 ( m χ =233 GeV) background 0 . 01 5 10 20 50 100 200 E e + [GeV] Bergström, TB & Edsjö, PRD ’08 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 26

SUSY DM and PAMELA Bergstr¨ om, Bringmann & Edsj¨ o (2008) Neutralino annihilation 0 . 2 helicity suppressed: PAMELA HEAT � σ v � ∝ m 2 α em 0 . 1 ℓ m 2 π χ e + / ( e + + e − ) Surprisingly hard 0 . 05 spectra possible if dominates! χχ → e + e − γ first attempt to connect BM5’ ( m χ =132 GeV) 0 . 02 PAMELA to DM BM3 ( m χ =233 GeV) background but : enormous boost 0 . 01 5 10 20 50 100 200 factors needed w.r.t. E e + [GeV] Bergström, TB & Edsjö, PRD ’08 thermal cross section... ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 26

Other DM explanations By now, a large number of further DM-related attempts to explain the PAMELA data has appeared on the market Subsequent data seem to confirm the excess Model-independent analysis: strong constraints on hadronic modes from data ¯ p χχ → e + e − or µ + µ − favoured large boost factors generic ‒ O (10 3 ) Bergström, Edsjö & Zaharijas, PRL ’09 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 27

Other DM explanations By now, a large number of further DM-related attempts to explain the PAMELA data has appeared on the market Subsequent data seem to confirm the excess Model-independent analysis: strong constraints on hadronic modes from data ¯ p χχ → e + e − or µ + µ − favoured large boost factors generic ‒ O (10 3 ) highly non-conventional DM models needed! Bergström, Edsjö & Zaharijas, PRL ’09 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 27

Other DM explanations By now, a large number of further DM-related attempts to explain the PAMELA data has appeared on the market Subsequent data seem to confirm the excess Model-independent analysis: strong constraints on hadronic modes from data ¯ p χχ → e + e − or µ + µ − favoured large boost factors generic ‒ O (10 3 ) highly non-conventional DM models needed! Bergström, Edsjö & Zaharijas, PRL ’09 Besides: DM by far not the only explanation... ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 27

Astrophysical sources Propagation uncertainties not the main problem: secondaries ~ 2-4 Delahaye et al. , A&A ’09 primaries ~ 5 Delahaye et al. , PRD ’08 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 28

Astrophysical sources Propagation uncertainties not the main problem: secondaries ~ 2-4 Delahaye et al. , A&A ’09 primaries ~ 5 Delahaye et al. , PRD ’08 i.e. much better than for primary antiprotons: for , energy loss is dominant must be locally produced (~ kpc) e ± very difficult to explain PAMELA data without primary component ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 28

Astrophysical sources Propagation uncertainties not the main problem: secondaries ~ 2-4 Delahaye et al. , A&A ’09 primaries ~ 5 Delahaye et al. , PRD ’08 i.e. much better than for primary antiprotons: for , energy loss is dominant must be locally produced (~ kpc) e ± very difficult to explain PAMELA data without primary component but : many good astrophysical candidates for primary sources in the cosmic neighbourhood! Grasso et al., ApP ’09 pulsars Yüksel, Kistler & Stanev, PRL ’09 Profumo, 0812.4457 Malyshev, Cholis & Gelfand, PRD ’09 old supernova remnants Blasi, PRL ’09 Blasi & Serpico, PRL ’09 GRB Ioka, 0812.4851 Large arm/interarm difference in SN rate Shaviv, Nakir & Piran, PRL ’09 effect of SNR on near dense cloud Fujita, Kohri, Yamazaki & Ioka, PRD ’09 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 28

Astrophysical sources Propagation uncertainties not the main problem: secondaries ~ 2-4 Delahaye et al. , A&A ’09 primaries ~ 5 Delahaye et al. , PRD ’08 i.e. much better than for primary antiprotons: for , energy loss is dominant must be locally produced (~ kpc) e ± very difficult to explain PAMELA data without primary component but : many good astrophysical candidates for primary sources in the cosmic neighbourhood! Grasso et al., ApP ’09 pulsars see talk by Yüksel, Kistler & Stanev, PRL ’09 Profumo, 0812.4457 S. Sarkar Malyshev, Cholis & Gelfand, PRD ’09 old supernova remnants Blasi, PRL ’09 Blasi & Serpico, PRL ’09 GRB Ioka, 0812.4851 Large arm/interarm difference in SN rate Shaviv, Nakir & Piran, PRL ’09 effect of SNR on near dense cloud Fujita, Kohri, Yamazaki & Ioka, PRD ’09 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 28

Multi-messenger approaches So far: DM solution maybe not most natural ‒ but at least an (exciting!) possibility... ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 29

Multi-messenger approaches So far: DM solution maybe not most natural ‒ but at least an (exciting!) possibility... In order to disentangle these possibilities (astro- physical vs. DM), cleaner spectral signatures are needed wait for upcoming higher statistics experiments ??? ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 29

Multi-messenger approaches So far: DM solution maybe not most natural ‒ but at least an (exciting!) possibility... In order to disentangle these possibilities (astro- physical vs. DM), cleaner spectral signatures are needed wait for upcoming higher statistics experiments ??? More promising ‒ and probably anyway needed ‒ is the combination of different detection channels! ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 29

“A theory of dark matter” Arkani-Hamed, Finkbeiner, Slatyer & Weiner, PRD ’09 idea : introduce new force in dark χ φ χ φ sector, with m φ � 1 GeV φ ... φ large annihilation rates (Sommerfeld enhancement) φ → e + e − or µ + µ − (kinematics!) m φ ∼ GeV later decay: φ φ χ a) χ ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 30

“A theory of dark matter” Arkani-Hamed, Finkbeiner, Slatyer & Weiner, PRD ’09 idea : introduce new force in dark χ φ χ φ sector, with m φ � 1 GeV φ ... φ large annihilation rates (Sommerfeld enhancement) φ → e + e − or µ + µ − (kinematics!) m φ ∼ GeV later decay: φ φ χ a) χ but : strong constraints from (IB) and radio (synchroton) ! γ Bertone, Bergström, TB, Edsjö & Taoso, PRD ’09 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 30

Galactic diffuse emission A more conservative approach relies only on local observations and quantities Regis & Ullio, PRD ’09 0 10 R = 8 kpc E e = 200 GeV 2 (arbitrary normalization) ~ " -1 10 e -1 ] M D -1 sr y r a -2 s m i r p ! e [MeV cm R -2 secondary at source C 10 Φ e secondary in ISM -3 10 -4 10 -4 -3 -2 -1 0 1 2 3 4 z [kpc] ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 31

Galactic diffuse emission A more conservative approach relies only on local observations and quantities Regis & Ullio, PRD ’09 0 10 R = 8 kpc E e = 200 GeV 2 (arbitrary normalization) ~ " -1 10 e -1 ] M D -1 sr y r a -2 s m i r p ! e [MeV cm R -2 secondary at source C 10 Φ e secondary in ISM -3 10 -4 10 -4 -3 -2 -1 0 1 2 3 4 z [kpc] Primary/secondary astrophysical source localized at z=0 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 31

Galactic diffuse emission A more conservative approach relies only on local observations and quantities Regis & Ullio, PRD ’09 0 10 R = 8 kpc E e = 200 GeV 2 (arbitrary normalization) ~ " -1 10 e -1 ] M D -1 sr y r a -2 s m i r p ! e [MeV cm R -2 secondary at source C 10 Φ e secondary in ISM -3 10 -4 10 -4 -3 -2 -1 0 1 2 3 4 z [kpc] DM contribution Primary/secondary extended astrophysical source localized at z=0 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 31

Galactic diffuse emission A more conservative approach relies only on local observations and quantities Regis & Ullio, PRD ’09 0 10 R = 8 kpc E e = 200 GeV 2 (arbitrary normalization) ~ " -1 10 e -1 ] M D -1 sr y r a -2 s m i r p ! e [MeV cm R -2 secondary at source C 10 Φ e secondary in ISM -3 10 -4 10 -4 -3 -2 -1 0 1 2 3 4 z [kpc] DM contribution Primary/secondary extended astrophysical source handle on this by localized at z=0 Fermi/Planck !? ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 31

Galactic diffuse emission A more conservative approach relies only on local observations and quantities Regis & Ullio, PRD ’09 -2 0 10 10 o < l < 360 o R = 8 kpc 0 o < b < 60 o CR total 50 E e = 200 GeV EGB DM ! 2 (arbitrary normalization) ~ " DM ! -1 10 DMe -3 -1 ] 10 e -1 ] M D -1 sr -1 sr y r -2 s a -2 s m i r p 2 J [Mev cm ! e [MeV cm R -2 secondary at source C 10 Φ e -4 secondary in ISM E 10 -3 10 -5 -4 10 10 1 2 3 4 5 6 -4 -3 -2 -1 0 1 2 3 4 10 10 10 10 10 10 z [kpc] E [MeV] DM contribution Primary/secondary IC+FSR emission from DM extended astrophysical source component could be seen handle on this by localized at z=0 against diffuse background Fermi/Planck !? ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 31

Diffuse -ray constraints γ Already EGRET data in some tension with annihilating WIMP explanation of PAMELA Prediction for Fermi: even decaying DM could be excluded! Borriello, Cuoco & Miele, PRL ’09 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 32

Diffuse -ray constraints γ Already EGRET data in some tension with annihilating WIMP explanation of PAMELA Prediction for Fermi: even decaying DM could be excluded! PAMELA ψ → µ + µ − , Einasto +Fermi 10 27 +Hess 10 26 Τ dec � sec � τ dec [s] 10 25 After 1yr Fermi FERMI 10 ° � 20 ° 10 24 FERMI Gal. Poles Isotropic 10 23 10 2 10 3 10 4 Borriello, Cuoco & Miele, PRL ’09 m ψ [GeV] m Χ � GeV � Cirelli, Panci & Serpico, 0912.0663 ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 32

Multi-Wavelength E.g. the Galactic Center: An interesting target for multi-wavelength searches! Regis & Ullio, PRD ’08 -22 E [eV] 10 -6 -4 -2 0 2 4 6 8 10 12 14 10 10 10 10 10 10 10 10 10 10 10 T S A L C G T -9 EGRET A 10 J1746-2851 _ _ Melia & Falcke __ _ _ -24 10 VLA (LaRosa et al) -11 VLT 10 -2 ] -1 ] -1 cm _ _ 3 s " v [cm ! S " ! #! [erg s HESS excluded by J1745-290 -13 10 Narayan et al. IR/NIR/XR ! -26 10 CHANDRA VLA (D configuration) N sp -15 10 _ _ b - b -28 10 -17 10 1 2 3 4 10 10 10 10 8 10 12 14 16 18 20 22 24 26 28 10 10 10 10 10 10 10 10 10 10 10 M ! [GeV] ! ! [Hz] Gamma rays not necessarily most constraining! ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 33

How far can we go? Impressive improvements of direct detection limits in recent years! Potential of indirect searches not yet fully capitalized: small eff. areas (Fermi) relatively short observation times (HESS, VERITAS, MAGIC, …) CTA will have a greatly improved performance, but has many interesting (astrophysical) targets to observe � access to observation time will continue to be an issue ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 34

How far can we go? Impressive improvements of direct detection limits in recent years! Potential of indirect searches not yet fully capitalized: small eff. areas (Fermi) relatively short observation times (HESS, VERITAS, MAGIC, …) CTA will have a greatly improved performance, but has many interesting (astrophysical) targets to observe � access to observation time will continue to be an issue What could a dedicated future dark matter indirect detection experiment achieve? Let’s think BIG…! ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 34

The Dark Matter Array Focus on a CTA-like design with a large array of Cherenkov Telescopes ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 35

The Dark Matter Array Focus on a CTA-like design with a large array of Cherenkov Telescopes aim at A e ff CTA � 10 km 2 DMA ∼ 10 × A e ff ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 35

The Dark Matter Array Focus on a CTA-like design with a large array of Cherenkov Telescopes aim at A e ff CTA � 10 km 2 DMA ∼ 10 × A e ff Best achievable energy threshold? ‒ Torsten Bringmann, University of Hamburg Indirect Dark Matter Searches 35

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