Dark matter searches with GLAST

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1 Dark matter searches with GLAST Larry Wai SLAC Representing the GLAST LAT Collaboration Dark Matter and New Physics working group

2 GLAST Large Area Telescope (LAT) 20 MeV 300 GeV 1.8 m γ Anti-Coincidence Detector 4% R.L. 89 scintillating tiles efficiency (>0.9997) for MIPs 1.0 m e + e Tracking detector 16 tungsten foils (12x3%R.L.,4x18%R.L.) 18 pairs of silicon strip arrays strips (228 micron pitch) Calorimeter 8.5 radiation lengths 8 layers cesium iodide logs 1536 logs total (1200kg) Larry Wai / SLAC 2

3 The LAT at SLAC (October 2005) Huge silicon strip detector array - 80sq.m.! 28-Oct-2005, SLAC Larry Wai / SLAC 3

4 The LAT at NRL (May 2006) Ship to SASS in September 2006 Launch in September 2007! Larry Wai / SLAC 4

5 GLAST LAT Collaboration France IN2P3, CEA/Saclay Italy INFN, ASI Japan Hiroshima University ISAS, RIKEN Principal Investigator: Peter Michelson (Stanford & SLAC) ~225 Members (includes ~80 Affiliated Scientists, 23 Postdocs, and 32 Graduate Students) United States California State University at Sonoma University of California at Santa Cruz - Santa Cruz Institute of Particle Physics Goddard Space Flight Center Laboratory for High Energy Astrophysics Naval Research Laboratory Ohio State University Stanford University (SLAC and HEPL/Physics) University of Washington Washington University, St. Louis Sweden Royal Institute of Technology (KTH) Stockholm University Cooperation between NASA and DOE, with key international contributions from France, Italy, Japan and Sweden. LAT Managed at Stanford Linear Accelerator Center (SLAC) Larry Wai / SLAC 5

6 GLAST is a NASA Mission ¾Launch: September 2007 ¾Lifetime: 5-years (10-years goal) ¾Orbit: 565 km, circular ¾Inclination: 28.5o Large Area Telescope (LAT) 20 MeV GeV Observing modes: ¾All sky survey ¾pointed observations Re-pointing Capabilities: ¾Autonomous ¾rapid slew speed (75 in < 10 minutes) GLAST Burst Monitor (GBM) 5 kev - 25 MeV June 13, 2006 Larry Wai / SLAC 6

7 Dark matter as particles! WIMP pair annihilation to W, Z, or quark pairs time γ χ W - /Z/q π 0 γ χ _ W + /Z /q } π - π + ν µ µ - ν µ µ + ν µ ν e e + ν µ ν e e - Larry Wai / SLAC 7

8 Gammas from lines Branching fractions are in the range χ time? γ For γγ Line, energy = WIMP mass For WIMP masses > M Z /2 can also have γz 0 line χ χ γ γ Measurement of line branching fractions would constrain particle theory χ? Z 0 Larry Wai / SLAC 8

9 Where should we look for WIMPs with GLAST? Galactic center Galactic satellites Galactic halo Extra-galactic Larry Wai / SLAC 9

10 Example A. dark matter satellite 55-days GLAST in-orbit counts map (E>1GeV) Galactic Center Optimistic case: 70 counts signal, 43 counts background within 1.5 deg of clump center 30-deg latitude Larry Wai / SLAC 10

11 Dark matter source spectrum GLAST 55 days (10-sigma) Dark matter spectrum Diffuse background Molecular cloud spectrum Larry Wai / SLAC 11

12 How many observable dark matter sources? LSP WIMP (SUSY) GLAST 5-yrs LCC4 LCC2 Simulation of Milky Way dark matter satellites from Taylor & Babul (2004,2005) SUSY model definitions from Baltz, et.al. (2006); LCC2 and LCC4 are favorable to GLAST compared to LCC1 and LCC3. Larry Wai / SLAC 12

13 Satellite mass distributions All satellites (Taylor & Babul 2004,2005) Current simulation resolution limit dn/dm 5-sigma (GLAST 5-yrs) 10-sigma (GLAST 5-yrs) 20-sigma (GLAST 5-yrs) M=100GeV <σ A v> = 2.3x10-26 cm 3 s -1 Larry Wai / SLAC 13

14 Example B. Milky Way dark matter halo EGRET E γ >1GeV, point-source subtracted, Cillis & Hartman (2005) High latitude Region Disk Region Center Region Disk Region High latitude Region WIMP search sweet spot (Stoehr et.al. 2004) Larry Wai / SLAC 14

15 EGRET diffuse GeV excess Hunter et al (1997); similar GeV excess in all sky regions b <10deg, l <60deg GLAST no backsplash Can be explained with astrophysical mechanisms; i.e. SMR (2004) De Boer has claimed WIMP annihilation; i.e. De Boer, et.al. (2005) Larry Wai / SLAC 15

16 Example C: Galactic Center Mayer-Hasselwander (1998) - EGRET point source Spatial analysis 100MeV-300MeV (l ~ -0.75deg) 300MeV-1GeV (l ~ -0.30deg) > 1GeV (l ~ 0.05deg) > 5GeV (l ~ 0.20deg) New diffuse component in the galactic center region, HESS (2006) HESS (2004) EGRET GLAST Cesarini, Fucito, Lionetto, Morselli, Ullio (2003) 95% CL 95% 95% CL CL Hooper & Dingus (2004) x Galactic Center Hooper and Dingus (2002) Larry Wai / SLAC 16 Mayer-Hasselwander et.al. (1998)

17 Galactic center msugra sensitivity: small tan(β) regime (5 σ) See Baltz, et.al. (2006) for definition of LCC2. Note: position of this point is very sensitive to m t and this placement estimates the equivalent LCC2. Accelerator limits are from H. Baer, et al. (2004) Larry Wai / SLAC 17

18 Galactic center msugra sensitivity: large tan(β) regime (5 σ) See Baltz, et.al. (2006) for definition of LCC4. Note: position of this point is very sensitive to m t and this placement estimates the equivalent LCC4. Accelerator limits are from H. Baer, et al. (2004) Larry Wai / SLAC 18

19 Review The GLAST collaboration will search for WIMP annihilation gamma rays from 4 regions: galactic center, galactic satellites, galactic halo, and extragalactic If we locate a source consistent with WIMP annihilations, then we can constrain particle theory by measuring the line branching fractions (if not with GLAST, then perhaps with an IACT) Larry Wai / SLAC 19

20 GLAST a complementary way to observe dark matter signals! Experiments by DM location: At the earth s surface: direct detection (& colliders) In the earth s/sun s core: neutrino detectors In the galaxy: anti-matter & gamma ray detectors GLAST: Large field of view allows imaging of dark matter large fraction (16%) of WIMP mass converts to radiation in the GLAST energy range cosmic ray shield allows us to achieve low cosmic ray background Larry Wai / SLAC 20