Stefano Profumo

1. Stefano Profumo UC Santa Cruz Santa Cruz Institute for Particle Physics T.A.S.C. [Theoretical Astrophysics in Santa Cruz] New Physics with ACTs in the Fermi Era TeV Particle Astrophysics 2009 SLAC National Accelerator Laboratory, Menlo Park, CA, July 13-17, 2009

2. Annihilation debris: an unavoidable consequence of thermal WIMPs Gamma Rays 1. “Primary” • Hadronization, p0 gg • Final State Radition (e.g. L+L- g) • (included in e.g. DMFIT) • “Intermediate State” Radiation • (model-dependent, incl. in DSv5) • Loop-suppressed radiative • annihilation modes (gg, Zg, hg, …) Credit: Fermilab Website

3. 3. Compute the Signals (IC off CMB/starlight, Synchrotron emission,…) WIMP annihilation also produces stable Electrons and Positrons, which diffuse and loose energy Inverse Comptonoff CMB and starlight photons, Bremsstrahlungand Synchrotronemission produce radiation from radio to gamma-ray frequencies 1. Source Term 2. Transport Equation

4. Annihilation debris: an unavoidable consequence of thermal WIMPs Gamma Rays 1. “Primary” 2. “Secondary” • Inverse Compton (e+ge+g) • (where g from CMB, starlight, IRB…) • Bremsstrahlung • Synchrotron (for large enough B) Credit: Fermilab Website

5. The multi-wavelength spectrum expected from a 41 GeV “bino” annihilating in the Coma cluster Set by the DM particle mass scale “Environment”-dependent (B, gas density, diffusion) Colafrancesco, Profumo and Ullio (2005)

6. What is “magic” about gamma-ray telescopes for the search for dark matter? s ~ m2/mZ4 W ~ 1/s ~ m-2 W~m s ~ m-2 W ~ m2 They probe the energy range where the thermal cold DM mass scale is Baltz (2004)

7. What is “magic” about gamma-ray telescopes for the search for dark matter? Gamma-Ray “Debris” WIMP Mass Range Secondary & Low-E Primary Radiation Non-thermal Production

8. What is “magic” about gamma-ray telescopes for the search for dark matter? an “old” Morselli plot WIMP Mass Range Secondary & Low-E Primary Radiation Non-thermal Production

9. Role of ACT’s in the multi-frequency siege to dark matter in the Fermi Era 4. Cosmic Ray Electrons/ Positrons 1. Dwarf Galaxies 2. Galaxy Clusters 3. Galactic Center

10. Dwarfs: a lesson from CACTUS Solar Array ACT located at Solar Two, Daggett (CA), operated by UC Davis in ’04-’05 Observed PSR/SNR (Crab, Geminga), AGN (Mk421, 501) and dSph Draco Reported GR excess from Draco, later attributed to problems with noise assisted trigger threshold connected to starlight dSph are DM dominated and GR-quiet objects: the usual suspect, DM interpretation of the excess L.Bergstrom & D.Hooper, hep-ph/0512317 and S.Profumo & M.Kamionkowski, astro-ph/0601249

11. Dwarfs: a lesson from CACTUS Excess Counts !!! An important lesson: dSph are ideal targets for indirect DM searches Moreover: ACTs are complementary to satellite-based GR telescopes [EGRET didn’t detect Draco] S.Profumo & M.Kamionkowski, astro-ph/0601249

12. Dwarfs: general features of Fermi vs ACT • dark matter search sensitivity CACTUS signal  huge cross section ACT Limitation: low-energy threshold ACT Asset: Great sensitivity to final states producing hard GR spectrum!

13. Dwarfs: Fermi results (T. Jeltema’s talk) Preliminary • * Asset of Fermi: sensitivity to • Inverse Compton Gamma Rays! • * Large Uncertainties on Diffusion • in small extragalactic systems!

14. Dwarfs: Comparing MAGIC and Fermi Preliminary • * Even without IC, the Fermi survey-mode • gives it an edge over ACTs • * Comparable sensitivities for m~1 TeV, • ~100h ACT obs. time

15. Dwarfs: prospects for ACTs in the Fermi era Is it worth it for ACTs to observe local dSph to search for DM in the Fermi era? YES: one example: DM model that fits positron excess TeV particle mm Large Diffusion in dSph makes ACT much better than Fermi!

16. Dwarfs: prospects for ACTs in the Fermi era Another example: Standard Neutralino- type DM particle, negligible IC m~1 TeV, comparable sensitivities for Fermi vs ACTs m~5 TeV, ACTs can outperform Fermi

17. 2. Clusters: a new gamma-ray source class? * Largest bound dark matter structures * Non-thermal activity detected as synchrotron radio emission * Likely source of gamma rays from hadronic or leptonic primary cosmic rays * Not conclusively detected so far in gamma rays * Excess hard X radiation detected in a few cases Galaxy Cluster Abell 1689 Warps Space Credit: N. Benitez (JHU)

18. 2. Clusters: non-thermal activity from cosmic rays Ophiuchus cluster (hard X-ray from Integral, new radio data) Leptonic Scenarios alone fail to provide self-consistent explanation Potential complementarity between Fermi and ACTs Perez-Torres, Zandanel, Guerrero, Pal, Profumo, Prada and Panessa (2009)

19. 2. Clusters: new physics versus cosmic rays Signal from DM and from CR in local clusters of galaxies predicted to be comparable! Jeltema, Kehaijas and Profumo (2009)

20. 2. Clusters: new physics versus cosmic rays Most promising targets for New Physics: nearby (gas-poor) galaxy groups! Jeltema, Kehaijas and Profumo (2009)

21. 2. Clusters: ACT and Fermi searches H.E.S.S. Collaboration, A&A, astro-ph 0907.0727 (~8h observations)

22. 2. Clusters: ACT and Fermi searches Preliminary Again, Fermi signal dominated by IC, HESS by FSR More targets, biased towards those where the DM/CR ratio is larger, and brighter See Tesla Jeltema’s talk; paper in preparation by Fermi Coll.

23. 3. The Milky Way Center and fundamental physics Rich and complicated Region, with several sources, large diffuse emission, non-thermal activity

24. 3. The Milky Way Center and fundamental physics ACT and Fermi observations of Sag A* of fundamental importance to understand background to the (possibly) brightest DM source

25. 3. The Milky Way Center and fundamental physics In the limit of perfect control over the diffuse and Sag A* “background” Fermi can determine fundamental properties of DM from the GC Jeltema and Profumo (2008)

26. 3. The Milky Way Center and fundamental physics Self-consistent treatment of both the Sag A* source and DM emission must however include a multi-wavelength approach Regis and Ullio (2008)

27. 3. The Milky Way Center and fundamental physics With certain assumptions on magnetic fields at the GC, and on the DM annihilation final state Radio and X-ray data put the gamma-ray emission beyond Fermi sensitivity, marginally detectable by a CTA Regis and Ullio (2008)

28. 4. Electrons and Positrons Great data delivered by H.E.S.S. on high-energy e+e- flux Help understanding spectrum and origin of HE e+e- Relevance to New Physics: 1. Claim of anomalous features related to e+ excess 2. Feeds back to diffuse galactic gamma ray emission

29. 4. Electrons and Positrons Bottom line of Fermi e+e- analysis: * Hard spectrum * Compatible with diffuse CR models * Positron excess requires extra primary source Is there an “anomalous feature” in the Fermi data alone?

30. Is there a residual “anomalous spectral feature” in the Fermi data? Most probably NO: in the ~ TeV range • CR Source Spectrum Cutoff • Diffusion Radius comparable • to mean SNR separation  • source stochasticity effects! • [breakdown of spatial continuity • and steady-state hypotheses] 1-s band for large set of random SNR realizations

31. 4. Electrons and Positrons: role of ACT’s • Maximize overlap with Fermi data at >TeV • Check for potential Anisotropy? • Cross check HESS results with other ACT • Re-calibrate ACT results after Fermi data with GR sources • Follow-up on potential local sources of e+e-

32. Conclusions New Physics with ACTs in the Fermi Era • Complementary Observations • (e.g. dwarfs, clusters, GC, e+e-) • ACTs: Potential for Discovery • even in Fermi era • (e.g. clusters as new GR sources, dwarfs) • Fundamental to understand • and control Background • (e.g. clusters, GC, e+e-)