Searches for Dark Matter with GLAST

1. Gamma-ray Large Area Space Telescope Searches for Dark Matter with GLAST Bill Atwood SCIPP/UCSC Glast Science Lunch 5-Aug-2004

2. Road Map for Photons from Dark Matter Where Galactic Center Known Location Intensity Dependence Diffuse Character Extra Galactic Associated with AGN Point Like Character Type Line XXgg, gZ0 (Small Br, Line Spectra) Inclusive XX g + Anything (Large Br, Continuum Spectra) Particle Source SUSY X: c0 (LSP - many models parameter space large) LIMP X: Heavy nR (Signal to weak too be observed by GLAST) Focus on Galactic Center

3. EGRET to GLAST: Galactic Diffuse g ray Emission near the GC - PSF is Important GLAST GC source in LAT ~ 10 arc-sec location for bright sources EGRET

4. Gamma Ray Flux From WIMPS The flux of gamma rays from WIMP annihilation has many terms: Cesarini et al, astro-ph/0305075 Annihilation Cross Section & Thermal Velocity Branching Fraction & Photon Spectrum WIMP Number Density : Angle away from Galactic Center : Line-of-Sight in direction l.o.s Recasting & Scaling in terms of nominal values Units: cm-2s-1GeV-1sr-1 With:

5. Density Models a = core halo radius / pwr. law break pt. ~ 3 kpc g = Cusp. parm. (0= no cusp.)a bg Isothermal profile220 Navarro-Frenk-White131 Moore et al… 1.531.5 Kravtsov et al.(a) 2 30.2 Kravtsov et al.(b)2 30.4 Largest Uncertainty in Predicted Rate WIMP Density Parameterization GLAST Angular Resolution per Photon ~ .1o above ~ 10 GeV r/rc Navarro-Frenk-White Kravtsov et al. Isothermal GOOD NEWS! Recent evidence from analysis of INTEGRAL data suggests .4 < g < .8 Orders of Magnitude Uncertainty in J(Y) Boehm et al, astro-ph/0309686 Phys.Rev.Lett. 92 (2004)

6. Example of Predicted Gamma Ray Flux GLAST Sensitivity where = (.6 x 104) (5yrs x p x 107) (.33) (.8) = 2.5 x 1011 cm2-s Integrated Sensitivity 1 Photon - 5 year Integrated Glast Sensitivity Limit Setting Ng =1 use a = 2.7 L. Berstrom, P.Ullio & J.Buckley 1998 Note: Rates could be < 10x Smaller due to r(r)

7. Experimental & Interpretation Issues • Wash-up of Low Energy Events to Hi-energy • Energy Resolution (Line Spectra) • Astrophysical Source Pollution • Diffuse Background Some of what follows are PRELIMINARY Analyses and do not represent either an Optimal or Final Analysis

8. Wash-up of Lower Energy Photons • Correction to Meas. Energy • Leakage • Edges Mod. Hi-E Tail Cumulative Error can be large Low-Energy Hi-Energy Large Hi-E Tail Prob > .25 Eff = 92% All Probs. CAL-Hi Total Correction Factor 3.5 GeV < E RECON < 180 GeV -1 < cos(q) < -.3 PRELIMINARY! Small Hi-E Tail Criteria for quality of energy measurement: Classification Tree based Probability using event specific variables Prob > .80 Eff = 75%

9. Hi - Energy Resolution Energy Resolution Integrated over Field-of-View Present Calc. gives 10% or Better well past 100 GeV 3 - 10 GeV 30 - 100 GeV PRELIMINARY! dE/E dE/E 10 - 30 GeV 100 - 180 GeV dE/E dE/E

10. Cbb Cbl Clb Cll Source Polution : Multivariate Analysis The task is to take two reconstructed photons and to 1) combine them to make the covariance weight sum (optimal average location) 2) Find the "c2" for this association Photon descritpion: 3 parameters - 2 angles and an energy: x = (b, l) & E Errors on parameters x : C = C = <(x-xmc)(x-xmc)T> C-1(1)*x(1)+ C-1(2)*x(2) <x> = C-1(1) + C-1(2) (C-1(1) + C-1(2))-1 and C(1+2) = c2 = (x(1)-<x>)T CRES(1)-1 (x(1)-<x>) + (x(2)-<x>)T CRES(2)-1 (x(2)-<x>) where CRES(1,2) = C(1,2) - C(1+2)

11. FastSim Data A "quick and dirty" source to photons with which to export PSF Aeff

12. -.6 < cos(q) < -.8 -.8 < cos(q) < -1. -.4 < cos(q) < -.6 -.2 < cos(q) < -.4 FastSim Covariance Error Ellipses for 1 GeV Photons LAT f orientation held fixed (otherwise all would smear to circular distributions)

13. FastSim Data Samples Mc Truth FastSim

14. An Energy Flow Statistic Algorithm: 1) For all photons - find the closest photon (smallest angular separation) 2) Form the <x> and c2 for this pair 3) Compute: EFlow = & Log10(EFlow) 10 Source + Diffuse Example

15. FastSim Data Samples (2) 800 Sources in 1 str. Diffuse

16. 800 Sources (Closer to Reality!) Diffuse/Source Diffuse Efficiency

17. Applications 1) Dark Matter signal form Galactic Center (Show that its Diffuse) 2) Large Scale Structure (Bias data to be Sources - Study Sph. Harm.) 3) Extra-Galactic Diffuse (Is there any?) 4) Characterizing Halo's

18. Diffuse Background at Galactic Center Galactic Center Region has excess > GeV g's compared to conventional galactic diffuse model (GALPROP) GALPROP (local CR Spectra) GALPROP (Optimized CR Spectra) A.W.Strong, I.V. Moskalenko, & O. Reimer astro-ph/0406254 Good News: Diffuse Background small at Hi-Energy Bad News: Reasonable changes to CR Spectra fit the data well

19. LHC SUSY Reach LHC is a "SUSY Discovery Machine" Abe Seiden LHC Turn On – 2007 Covers Most(?) of GLAST Discovery Space in a very short time Plausible scenario: LHC Discovers SUSY and sets parameters GLAST Measures the Role it plays in CDM Plot courtesy of Abe Seiden from HEPAP presentation, April 2004

20. Optimism: EGRET Data & SUSY Models A.Cesarini, F.Fucito, A.Lionetto, A. Morselli, P.Ullio, astro-ph/0305075 Fit to EGRET Data GLAST Data Prediction

21. Summary • The GLAST-LAT is well along in the build of flight hardware • Scheduled Launch in 2007 • Adequate Sensitivity for detecting a portion of SUSY Neutralino Models Space • Detailed event-by-event description will aid in reducing energy and unresolved-source systematics • Given current background estimates, may be adequate to detect line structure