1. PRESENT AND FUTURE DARK MATTER SEARCHES WITH IMAGING ATMOSPHERIC CHERENKOV TELESCOPES J-F. Glicenstein IRFU, CEA-Saclay

2. Outline − Imaging Atmospheric Cherenkov Telescopes − Indirect dark matter searches with IACT − Results on the Galactic Halo (H.E.S.S) − Dwarf Galaxies: Segue (MAGIC, VERITAS) − Galaxy clusters: Fornax (H.E.S.S) − Dark matter searches with CTA

3. 3 Major Active IACTs H.E.S.S. MAGIC VERITAS

4. High Energy Stereoscopic System located in Namibia, latitude=-23 o, altitude=1800 m 4 telescopes, 107 m 2 each cameras 960 PMT FOV= 5 o trigger threshold=100GeV installed: january 2004 installation of 5 th telescope in 2011, first light expected 2012 mirror: 600m 2, 2048 PMT, FOV=3.5 o, trigger threshold=20 GeV

5. Major Atmospheric Gamma-ray Imaging Cherenkov located in La Palma (Canaries Islands), latitude=+29 o, altitude=2225 m mirror: 234 m 2 camera 534 PMT FOV=3.5 o trigger threshold=60 GeV installed late 2004 installation 2 nd telescope in 2009 mirror 234m 2, 1099 PMT

6. Very Energetic Radiation Imaging Telescope Array System origin: Whipple collaboration (10 m, late 80s) located in Arizona,latitude=+32 o, altitude=1275 m 4 telescopes, 106 m 2 each cameras 499 PMT FOV=3.5 o trigger threshold=100 GeV installed in april 2007

7. Gamma- ray ~ 10 km Particle shower ~ 1 o Cherenkov light ~ 120 m 11 2  3 4 − brief flash ~3 ns − steroscopy: cosmic ray background rejection improved gamma ray reconstruction Imaging atmospheric Cherenkov telescopes

8. VHE gamma-ray astronomy: catalog of sources Moriond Cosmology 2012Present and future DM searches with IACT8 The VHE gamma-ray sky (November 2011) http://www.mppmu.mpg.de/~rwagner/sources/ ~100 sources (60 galactic)

9. Indirect DM searches with IACTs Moriond Cosmology 2012Present and future DM searches with IACT9 WIMP annihilation flux into  rays observed by an IACT: particle modelf AP : dark halo model − Most current particle models: − neutralinos (MSSM) − U Extra Dimensions (Servant, Tait 2003) boson B − leptophilic models (PAMELA excess) − decaying dark matter − Astrophysical factor:  dense targets Galactic Center nearby dwarf galaxies, globular clusters galaxy clusters (Fornax) dark matter clumps

10. Signal boosts: particle physics Moriond Cosmology 2012Present and future DM searches with IACT10 FSRIB relative velocity  – Sommerfeld effect: effective low velocity dispersions resonances at: – Internal Brehmstrahlung annihilation to W + W -,ff ( heavy higgsino-like)

11. Signal boosts: astrophysics Moriond Cosmology 2012Present and future DM searches with IACT11 Boost effect B from unresolved DM clumps estimated with Aquarius simulation (Springel et al 2008) B sensitive the assumed value of M lim ( M lim -0.226 ) B ~ (a few) for point-like searches towards dwarf galaxies B up to 2 order of mag. for extended searches (galaxy clusters) M lim = 10 -6 M ⊙ M lim = 5 10 -3 M ⊙ Fornax galaxy cluster

12. HESS searches towards the Galactic halo Moriond Cosmology 2012Present and future DM searches with IACT12 − 112 hours collected (2004-2008) − 1 degree around GC − galactic plane (|b| < 0.3 o ) excluded − background estimated by reflected bakground technique

13. H.E.S.S. limits on WIMP annihilation in the Galactic halo Moriond Cosmology 201213Present and future DM searches with IACT Excluded 95% C.L. mSUGRA models A.Abramovski et al. (HESS), Phys.Rev.Lett 106, 161301 (2011)

14. Searches towards globular clusters: M15 Moriond Cosmology 2012Present and future DM searches with IACT14 UM i Draco M15 (adiabatic compression) MSSM + WMAP constraints Same (Woods et al) DM halo modelling Excluded (95% CL) HESS limit very small 0.04 pc core low metalicity (“primordial”) not dominated by DM WHIPPLE Woods et al (Whipple) 2008: constraints at the 10 -23 level (1.2 hour!) A.Abramovski et al (HESS) ApJ 735 11 (2011): also at 10 -23 level (15.2 h) takes into account heating of DM by stars in GC core

15. Dwarf spheroidal galaxies Moriond Cosmology 2012Present and future DM searches with IACT15 dark matter dominated mass range: 10 7 -10 9 M ⊙ observed by IACTs: Sagittarius, Carina, Sculptor, Draco,Willman1, Segue1, Umin, Canis Major, Boötes 1 data on surface brightness, velocity dispersion, globular clusters, colors  galactic structure well modeled Walker et al 2007 Belokurov et al 2006

16. Segue 1 dwarf galaxy Moriond Cosmology 201216Present and future DM searches with IACT − discovered 2006 in the SEGUE (Sloan) catalog by Belokurov et al. − located 23±2 kpc from the Sun − located at the intersection of Saggitarius and Orphan stellar streams − unclear whether dwarf galaxy or globular cluster − only 71 stars resolved. − velocity dispersion =3.7±1.5 km/s M = 5.8 10 6 M ⊙ − seems dominated by DM, but error on mass ~ 100% log (core radius) MVMV GC dwarf galaxies

17. MAGIC observations of Segue1 dwarf Moriond Cosmology 201217Present and future DM searches with IACT − single telescope observations (MAGIC1), taken in 2008-2009 − ~ 29.5 h good data − no evidence for signal − Segue 1 dwarf model was modelled as an Einasto profile (Essig et al 2010) − analysis in a slightly extended region ||< 0.14 o (= 10 -5 sr) − J( = 1.78 10 19 GeV 5 /cm 2 sr E min = 100 GeV

18. MAGIC searches towards Segue1: MSUGRA exclusion Moriond Cosmology 201218Present and future DM searches with IACT Excluded 95% C.L. 2  errors on J() (uncertainty on M) J.Aleksic et al. (MAGIC), JCAP 06 035(2011) min ~ 10 -23 cm 3 s -1     

19. VERITAS observations of Segue 1 dwarf Moriond Cosmology 201219Present and future DM searches with IACT − 48.7 hours obtained in 2010 and 2011 − no evidence for signal − same Einasto profile than the MAGIC paper − analysis in region  < 0.12 o − J() = 7.7 10 18 GeV 5 /cm 2 sr -E min = 300 GeV -Significance of signal inside  <0.12 o : 1.4  -”contamination” by bright star(-Leonis) -removed from background evaluation target

20. VERITAS searches towards Segue 1: exclusion limits Moriond Cosmology 201220Present and future DM searches with IACT min ~ 2 10 -24 cm 3 s -1 (    ) from thermal models Excluded 95% C.L. E.Aliu et al (VERITAS), PRD 85, 062001 (2012)

21. VERITAS searches towards Segue 1: boosts Moriond Cosmology 201221Present and future DM searches with IACT Wino-like neutralino self-annihilation self-annihilation to a 250 GeV particle pair E.Aliu et al (VERITAS), PRD 85, 062001 (2012) Excluded 95% C.L. from thermal models

22. Searches towards Segue 1: leptophilic models Moriond Cosmology 201222Present and future DM searches with IACT A fraction of parameter space excluded by MAGIC @ low energy and VERITAS @ high energy MAGIC VERITAS

23. Sagittarius dwarf galaxy Moriond Cosmology 201223Present and future DM searches with IACT old limits − recent observations of Sgr stream allows better modelling of Sgr Dwarf (closest dwarf) − update on former HESS limits by Viana et al (Astroparticle Physics 2012) − should be detectable with CTA (M wimp a few TeV,200 h observation) − However, expected signal from msecond pulsars in M54 (background) also detectable at 4-60  HESS CTA

24. The Fornax galaxy cluster Moriond Cosmology 2012Present and future DM searches with IACT24 − distance d=19 Mpc − central galaxy NGC1399 with a passive SMBH (10 9 M ⊙ ) − total mass ~ 10 14 M ⊙, extends over 1 Mpc (6 o ) − dark matter distribution well studied with X-rays, globular clusters, stars etc − 2 approaches in modelling: − assume NFW profile with concentration param. from virial mass (RB02) − use directly measured profiles Schuberth et al (2009 ) X rays GC

25. H.E.S.S. observations of the Fornax galaxy cluster Moriond Cosmology 201225Present and future DM searches with IACT − 14.5 hours of data obtained in 2005 − “minimal energy” of observations: E min = 260 GeV − boost effect expected from substructure  signal in extended regions − signal region: −  < 0.1 o, significance S = 2.3  − < 0.5 o, significance S=1.2 − < 1 o, significance S=0.6

26. HESS limits on Fornax: effect of source extension Moriond Cosmology 2012Present and future DM searches with IACT26

27. H.E.S.S. results on Fornax: WIMPs exclusion Moriond Cosmology 201227Present and future DM searches with IACT A. Abramovski et al., arXiv1202.5494 (2012), accepted in ApJ.

28. H.E.S.S limits on Fornax: KK models Moriond Cosmology 201228Present and future DM searches with IACT

29. HESS results on Fornax: boost factors Moriond Cosmology 201229Present and future DM searches with IACT Excluded 95% CL

30. The next generation of IACTs: CTA (2015) Moriond Cosmology 201230Present and future DM searches with IACT low energy section E thresh ~ 10 GeV 4 ø = 23 m telescopes core array 100 GeV-10 TeV 23 ø = 12 m telescopes high energy section 32 ø =5-6 m tel. on 10 km 2 area 2 arrays: north+south  all-sky coverage

31. Sensitivity of CTA Moriond Cosmology 2012Present and future DM searches with IACT31 x 10 flux sensitivity gain energy range increase Flux sensitivity for a 50 h observation

32. Dwarf galaxy searches with CTA Moriond Cosmology 201232Present and future DM searches with IACT Low energy High energy Several arrays layout studied Sculptor Segue 1 Courtesy A. Viana D.Nieto

33. dwarf galaxies with CTA (2) Moriond Cosmology 201233Present and future DM searches with IACT Boost factor A signal from Willman 1 or Segue 1 may be observable with CTA depending on boost factor.

34. Galactic plane flux sensitivity (CTA) Moriond Cosmology 2012Present and future DM searches with IACT34 ― assume E min = 50 GeV ― 500 GeV WIMP annihilating to bb ― x10 gain in effective area, x2 gain in hadron rejection ― reaches 10 -13 cm -2 s -1 sensitivity, except on new sources ~ 400 hours total 10 hours each bin

35. Searches for clumps Moriond Cosmology 2012Present and future DM searches with IACT35 HESS sensitivity ― clumps from ViaLacteaII (Diemand, Kuhlen, Madau, 2008) ― ~10 4 resolved halos in MW (M>10 5 M sol ) ― 10 3 random realizations (rotate the observer position @8.5 kpc) ― 168±44 clumps inside HESS galactic survey

36. Expected limits with clumps (galactic plane) Moriond Cosmology 2012Present and future DM searches with IACT36 Missing one order of mag. to reach thermal P.Brun, E.Moulin,J.Diemand, J-F.G, PRD 83, 015003 (2011)

37. Expected limits with clumps (1/4 sky) Moriond Cosmology 2012Present and future DM searches with IACT37 P.Brun, E.Moulin,J.Diemand, J-F.G, PRD 83, 015003 (2011) ― 1/4 survey in ~6 years ― assume 5 10 -13 cm -2 s -1 sensitivity (5 hour/bin) ― number of subhalos: 3907±324 ― thermal WIMPs region reachable

38. Conclusion − Best constraints on from observation by H.E.S.S of galactic halo − Many observations of dwarf galaxies. Most stringent constraints from observation of Segue 1 (Magic & Veritas) − The limits have important astrophysical systematics (GC vs dwarf galaxies, modelling) − Constraints on DM annihilation in the Fornax cluster (H.E.S.S) competitive with those from dwarf. − With planned array CTA, observations of Segue1, Willman1 reach the thermal annihilation region with proper boost − Searches for clump with CTA may give detections or provide stringent constraints. Moriond Cosmology 2012 Present and future DM searches with IACT 38

39. Back-up slides Moriond Cosmology 201239 Present and future DM searches with IACT

40. Moriond Cosmology 201240 Present and future DM searches with IACT

41. Moriond Cosmology 201241 Present and future DM searches with IACT

42. Moriond Cosmology 201242 Present and future DM searches with IACT

43. HESS searches towards the Galactic halo Moriond Cosmology 201243Present and future DM searches with IACT

44. 44 CTA: array design target performances Moriond Cosmology 2012 Present and future DM searches with IACT

45. 45 Present and future DM searches with IACT Moriond Cosmology 2012 Expectations for Galactic plane survey ― assumes ― x 2 improvement in hadron rejection ― x 2 gain in angular resolution ― x 10 gain in effective area  overall increase in sensitivity of ~ 9 ― expect ~ 300 sources in -30 deg≤ l ≤ 30 deg. Funk,Hinton,Hermann,Digel, arXiV0901.1885 HESS map of the Gal.plane, total exp ~500 hours simulated CTA map, flat exposure ~ 5 hours/field