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Reionizing the Universe with Dark Matter : constraints on self-annihilation cross sections

Reionizing the Universe with Dark Matter : constraints on self-annihilation cross sections. Fabio Iocco Marie Curie fellow at Institut d’Astrophysique de Paris. IDM 2010 Montpellier, 27/07/10. Indirect local DM searches.  ,  ‘ s: straight messengers. e + , p, e - …

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Reionizing the Universe with Dark Matter : constraints on self-annihilation cross sections

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  1. Reionizing the Universe with Dark Matter : constraints on self-annihilation cross sections Fabio Iocco Marie Curie fellow at Institut d’Astrophysique de Paris IDM 2010 Montpellier, 27/07/10

  2. Indirect local DM searches  , ‘ s: straight messengers e+, p, e- … subject to magnetic fields, diffusion, energy losses  ( r ) = smooth + clumps Astrophysical uncertainties: CR propagation, DM halo density profile, boost factor Courtesy of P. Salati

  3. Indirect searches of annihilating DM The SA DM signal (easily re-writable for decaying DM) astrophysics (structures) Particle physics Which line of sight? with substructures <2> ≥ <>2

  4. Constraining with multimessenger <sv>=<sv>e+ Aquarius Via Lactea [Pato et al. `09]

  5. Going early Universe Courtesy of NASA (through Google, Wikipedia, etc etc etc.)

  6. DM annihilation and the IGM C GeV -TeV scale e  g p keV scale W primary HE shower C Courtesy of T. Slatyer heating and ionization

  7. Isotropically averaged cosmological DM annihilation (easily re-writable for decaying DM) Smooth component Structure component Structure formation history (Press-Schechter / Sheth-Tormen) DM density halo profile Burkert / Einasto / NFW Only after structure formation z ≤ ≈ 100

  8. …and its absorption by the surrounding gas(coupling DM induced shower to IGM) “Opacity window” of the Universe Photoionization,IC scattering, pair production (on CMB  and matter), scattering [Slatyeret al. `09]

  9. “Reionization”: a history of free electrons  = 0.084   Ionized: Ly- free to pass by Neutral: Ly- absorber = neutral gas Completely ionized IGM z ~ 6 z

  10. Electron optical depth t Integrated quantity Known contribution Sources z > 6: known unknowns

  11. constraints(DM annihilations can overproduce free e-) To be integrated! In this models: no astrophysical sources (z > 6) Extra-conservative bounds! [Cirelli, FI, Panci `09]

  12. Transparency of the Universe& structure formation HE shower gets efficiently absorbed at high z Structure formation takes place in a late Universe (z < 60) [Slatyer et al.`09] [Cirelli, FI, Panci `09]

  13. Self-annihilating DM and the IGM The smooth DM component annihilates with a rate (per volume) (easily re-writable for decaying DM) Main effect of injected energy: ionization of the IGM depositing energy in the gas (IGM) at a rate free electron fraction, xe The only DM parameter is [Galli, FI, Bertone, Melchiorri `09]

  14. Self-annihilating DM and the CMB Modifying TT, TE, EE with additional e- (by DM annih) @ z >1000 , many e- no effects energy injection is small DM annihilation causes indirect effects, SZ by “additional” e- [Galli, FI et al. `09]

  15. Constraining DM with CMB [Galli, FI et al. `09]

  16. Evaluating “ f ” All channels, all secondaries, redshift dependence quarks leptons Branching ratio of DM annihilation essential for determining absorption XDM => e XDM =>  [Slatyer et al. 09]

  17. Constraining DM with CMB Thermal WIMP [Galli, FI et al. + Slatyer et al `09]

  18. Constraining Sommerfeld Enh. with CMB f = 0.5 cold DM !!!! zr=1000, 10-8 Sommerfeld saturated [Galli, FI et al. 09] A toy-Yukawa potential Sommerfeld enhancement

  19. Constraints on decaying DM Same principle, same physics, different “time dependence” of energy injection Constraints are not so strong: if the particles decay today, they did less decay in the past… DM t t Cirelli, FI, Ibarra, Panci, Tran: preliminary results!

  20. Comparing constraints [Catena et al. `10]

  21. Concluding It is possible to use Early Universe astrophysical observables to constrain DM properties Self-annihilating DM can inject enough energy (free electrons) to modify the cross correlation CMB spectra! Signal comes from smooth, cold DM density field (can get rid of structure formation uncertainties! And it rocks with SE) The detectability of a DM annihilation in the CMB signal is DM model dependent (annihilation channel) Would you ever believe we have found DM if I told you there is an (even strong) anomaly in the TE CMB spectrum?

  22. Observing Reionization:electrons and CMB z low(er) l polarization signal Damping of spectra

  23. Temperature constraints! “Exotic heating”: DM, after coupled f 1/3 heat, 1/3 ioniz. 1/3 Ly- [CIP 09]

  24. Pamela saga: the e+excess [Delahaye et al. `09] Evidence for e+ excess: primary positrons

  25. Combining the constraints on self-annihilating gammas +   + IGM temperature channel NFW profile [CIP 09] [Hurtzi et al 09]

  26. Einasto ee   NFW  ee   ee Burkert  [CIP `09]

  27. Galactic bounds and their uncertainties Radio constraints from GC (B=10 mG) [Bertone et al. `09] IC gamma constraints (from GC) [Cirelli & Panci `09]

  28. 5.1x10-4 ≤ Z ≤ 2x106 <sv> ≤ 10-21cm3/s Looser constraint than from anisotropies [McDonald, Scherrer, Walker ‘02] [Zavala, Volgersberger, White ‘09]

  29. The equation to Solve-I Energy deposition rate Gas (IGM) Opacity Annihilation rates

  30. The equation to Solve-II Evolution of ionization fraction Recombination rates Ionization rates

  31. Watching negative:gammas e+ e- boost IC Mainly IC photons z band breakup: locally dominated [Profumo & Jeltema 09]

  32. The Pamela(/Fermi/ATIC) saga IF intepreted as DM: High annih cross-section <v> ~10-24-10-21cm3/s Forget about thermal decoupling WIMP miracle e+ fraction Unless <v> = <v>(v) DM decoupling:  ~1 Recombination:  ~10-8 Small halos: 10-4 Milky Way:  ~10-4 “Sommerfeld” enhancement fulfills the requirements (higher masses preferred) e-+ e+ E [GeV] By courtesy of M. Cirelli

  33. Electron optical depth  Measured with CMB polarization Integrated quantity! WMAP 5 value

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