M. Vivier IRFU/SPP CEA-Saclay, France

1. Indirect searches for Dark Matter with the H.E.S.S. high energy g-rays telescope array. 43rd Rencontres de Moriond La Thuile (Val d'Aosta, Italy) March 15 - 22, 2008 M. Vivier IRFU/SPP CEA-Saclay, France Matthieu Vivier

2. High Energy Stereoscopic System An array of four imaging Cerenkov telescopes dedicated for VHE g-rays astronomy (E>100 GeV) ~ 30 institutes ~ 130 physicists & astrophysicists (mainly from France & Germany) MPI Kernphysik, Heidelberg LPTA Montpellier Humboldt Univ. Berlin IRFU Saclay Ruhr-Univ. Bochum CESR Toulouse Univ. Hamburg Durham Univ. LSW Heidelberg Dublin Inst. for Adv. Studies Univ. Tübingen Charles Univ., Prague Univ. Erlangen Yerewan Physics Inst. Ecole Polytechnique, Palaiseau North-West Univ., Potchefstroom APC Paris Univ. of Namibia, Windhoek Univ. Paris VI-VII N. Kopernicus Astr. Center, Warsaw Paris Observatory, Meudon Jagiellonian University, Cracow LAPP Annecy Institute of Nuclear Physics, Warsaw LAOG Grenoble Space research center, Warsaw Matthieu Vivier

3. VERITAS MAGIC H.E.S.S. CANGAROO III The 3rd generation Cerenkov telescopes in operation Matthieu Vivier

4. The H.E.S.S. telescope array Located in Namibia, at 1800m above sea level. • 4 telescopes in a square formation • 13 m diameter telescopes: mirror area of 107 m², camera of 960 PMTs covering a 5° FoV. • stereoscopic reconstruction • angular resolution < 0.1° • energy threshold ~ 100 GeV at zenith • sensitivity (5s): 1% Crab flux in 25 hrs Scientific goals: Cosmic rays physics (SNR, AGN,...) & DM… Matthieu Vivier

5. Predictions for Dark Matter annihilation fluxes Dark Matter mass distribution - obtained from numerical simulations or from observationnal data. - relatively large uncertainties in the inner part of the profiles (cusps or cores?) Particle Physics model - Neutralino annihilation (pMSSM scenarios) g-ray lines are loop suppressed continuum emission from hadronization of final states products (W±, Z0, quarks, mesons). - Kaluza-Klein annihilation (UED models) g-raylines are loop suppressed continuum emission from charged leptons and quarks. Matthieu Vivier

6. Potential targets for H.E.S.S. Targets with large DM concentration. • Galactic Centre: • - heliocentric distance: 8.5 kpc • standard g-ray emitters, important astrophysical background • diffuse emission along the galactic plane • Galaxy clusters centres: • -Virgo cluster (M 87), distance: 16.3 Mpc • - Variable emission incompatible with DM • Dwarf Spheroidal Galaxies: • 4 observable by H.E.S.S. at less than • 100kpc from the GC Matthieu Vivier

7. The Galactic Centre (HESS J1745-290) 2004 - 2006 ON source region Expected level of background events • ~ 100 hours of data taking (2004→2006) • statistical significance of the excess at the target position ~ 60 s • compatible withpoint-like source after subtraction of the diffuse emission (F. Aharonian et al., Nature 439 (2006) 695-698) Matthieu Vivier

8. SNR SgrA East (90 cm) Interpretations of the HESS J1745-290 signal • emission from SNR SgrA East? • vicinity of the Sgr A* black hole • correlation with X-ray/radio signal? (next slides) • interaction of protons or electrons with the ISM in central stellar cluster? • emission from PWN G359.94-0.04? • annihilations of WIMPs near GC ruled out (Aharonian et al, PRL, 97, 221102 (2006)) (next slides) • new preliminary result: l=359°56’41.1’’± 6.4’’± 6’’ b=-0°2’39.2’’ ± 5.9’’ ±6’’ van Eldik et al., ICRC (2007) • position of TeV signalincompatible with radio maximum SgrA East(7s) Matthieu Vivier

9. HESS J1745-290 energy spectrum • compatible with a power-law, cut-off energy > 6 TeV (95%CL) • spectral index:G = 2.29 ± 0.05 • integrated flux (>1 TeV)F = 1.87 ±0.1 10-12 cm-2 s-1 • no apparent spectral variability (2003  2005) Matthieu Vivier

10. Non-variability of the HESS J1745-290 signal 30th July 2005 No periodicities/flares (a few minutes  1 year) No correlation with X-rays (Chandra) J.Hinton, M.Vivier et al, (HESS) ICRC 2007 M.Vivier et al. (HESS) ICRC 2007 Matthieu Vivier

11. 14 TeV 5 TeV 10 TeV Galactic Centre: spectral constraints • KK, bb and t+t- spectra with PYTHIA 3.625 • poor fit at the low energy end  incompatible with a DM only source • F.Aharonian et al., Phys.Rev. Letters, 97, 221102 (2006) Matthieu Vivier

12. excluded (95% CL) MSSM limits KK limits MSSM+WMAP KK predictions MSSM predictions Galactic Centre: exclusion plots (p)MSSM predictions:DarkSusy 4.1 • MSSM limits: <sv> ≤ (1-10) 10-24 cm3.s-1 • KK limits: <sv> ≤ 10-24 cm3.s-1 Matthieu Vivier

13. Satellite galaxies of the Milky Way Matthieu Vivier

14. M54 • discovered in 1994 • distance: 24 kpc • behind the GC • core centered on M54 Majewski et al., (2003) The Sagittarius dwarf galaxy Matthieu Vivier

15. (Monaco et al 2004) "cusp" King model fit The Sagittarius dwarf galaxy • Spheroidal galaxy with a nucleus • Coincidence in position with the globular cluster M54 • Tidally distorted • Distance: 24 kpc - Theluminous profile has 2 components 1) diffuse component well fitted by a King model: rc = 1.6 kpc 2) compact component well fitted by a compact core: rc = 1.5 pc Point-like signal (core region much smaller than the H.E.S.S. PSF). Matthieu Vivier

16. Sagittarius dwarf: data analysis -Target position corresponding to the globular clusterM54: RA = 18h54m40s DEC = -30d27m05s (J2000) -11 hrs of live time after data selection (2006) -Mean zenith observation angle: 19° No significant excess at the target position (blue triangle). Signal region: 0.14° circular region centered on the target position Matthieu Vivier

17. Limits on the g-ray flux and sensitivity • Upper limit at the 95% C.L. on the number of g-rays at the target position (Feldmann & Cousins method): • The 95% C.L. limits on Ng provides a 95% C.L. upper limit on the velocity weighted cross-section, depending on the DM halo profile: NFW (with the Draco dwarf galaxy parameter, Evans et al. (2004)) Dark matter profile Core profile (parameters fitted on observationnal data) Matthieu Vivier

18. Constraints on WIMPs models pMSSM Kaluza-Klein <sv> ~ 2. 10-25 cm3s-1 (core) <sv> ~ 6. 10-24 cm3s-1 (NFW) <sv> ~ 5. 10-26 cm3s-1 (core) <sv> ~ 10-24 cm3s-1 (NFW) The core profile excludes KK models compatible with the DM relic density as measured by WMAP Some pMSSM models excluded in the case of the cored profile. Matthieu Vivier

19. Conclusions and perspectives • Galactic Centre: strong signal with no-variable emission. Probably not of a DM origin. Signal from Sgr A East excluded. • Sagittarius dwarf: no signal, strong constraints for a cored profile. • - pMSSM: <sv> ~ 2. 10-25 cm3s-1 • - KK: <sv> ~ 5. 10-26 cm3s-1 • -Many more results are coming soon (Canis Major, Sculptor, Carina). H.E.S.S. 2 is coming very soon ! (2009) - 5th telescope with larger dimensions: 28m in diameter - Lower energy threshold ~ 20 GeV : access to a larger part of WIMPs models Matthieu Vivier

20. Matthieu Vivier

21. The GC ridge diffuse emission GC Before subtraction of the G.09 and GC sources. SNR G.09 After subtraction of the G.09 and GC sources. The diffuse emission region correlates well to CS giant molecular clouds. Matthieu Vivier

22. Non-variability of the HESS J1745-290 signal -no peridiodicities in the H.E.S.S. signal (Lomb-Scargle periodogram & Rayleigh test) from a few minutes to one year. M.Vivier et al. (HESS) ICRC 2007 Matthieu Vivier

23. The radio-galaxy M87 in the Virgo cluster • Active Galaxy Nucleus (AGN) with a SMBH of (3.2± 0.9)109 Msolar • distance = 16.3 Mpc • jet axis not aligned with the line of sight (20-40 deg, not a blazar) • TeV emission first detected by HEGRA (2003) • HESS related paper: Aharonian et al., Science, 314 (2006), 1424 extension source TeV (99.9% CL) 3’ ≈ 13.7 kpc VLA 90 cm Matthieu Vivier

24. The M87 TeV signal as seen by H.E.S.S. • 13s detection in 89h (2003-2006) • point-like < 3’ (99% C.L.) • Power law energy spectrum: • G = 2.22 ± 0.15 (2005) • G = 2.62 ± 0.35 (2004) • Time variability in the measured flux: • on year timescale (3.2s) • on day timescale (4s) The time variability of the H.E.S.S. signal discards a sole DM origin and favors the central black hole as the production site of the TeV photons. Matthieu Vivier

25. Dark Matter annihilations fluxes predictions for M87 • «Fornengo et al (2004) » : HEGRA (MSSM) • profil halo Moore, • Mc=1 TeV, cc WW F(E>730 GeV) ~ 10-16 /cm2/s • HESS predictions: • energy threshold ~ 400 GeV • Halo model from « Romanowski & Kochanek (2001) » • NFW profile fitted on observationnal data • M(r) is well-constrained • prédiction flux F(E>100 GeV) ~ 10-15 /cm2/s ~1/1000 HESS sensitivity HESS Point Spread Fonction Radial mass profile of M87 «  Romanowski, Kochanek (2001) » Matthieu Vivier

26. Modelling the Sagittarius DM profile • Use the Jeans equation: • -observable: r luminous density, • <v2r> velocity dispersion • -Unknowns: M luminous+dark mass • b anisotropy • Assume b = 0: • -solve for M(r) to get rdark • or • -fit dark matter halo parameter to reproduce <v2r> • 2 DM halo considered: • -NFW (parameter fitted to <v2r>) • -cored profile (with <v2r> assumed to be flat, and analytic resolution of the Jean equation) Matthieu Vivier

27. Systematic uncertainties on the core modelling Core radius dependency qmax = 0.14° S0 = 24 kpc Matthieu Vivier

28. Systematic uncertainties on the core modelling Baryon fraction dependency Our modelling Factor 2 if the baryon fraction in 100% Matthieu Vivier

29. Systematic uncertainties on the core modelling Is the velocity dispersion profile asymptotically flat in the outer part of the halo? 50% effect on the value of Jbar Matthieu Vivier