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Constraints on large DM annihilation cross sections from the early Universe

Constraints on large DM annihilation cross sections from the early Universe. Fabio Iocco Institut de Physique Theorique, CEA/Saclay Institut d’Astrophysique de Paris. In collaboration with: G. Bertone, M. Cirelli, S. Galli, A. Melchiorri, P. Panci. TeVPA, SLAC 7/14/09.

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Constraints on large DM annihilation cross sections from the early Universe

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  1. Constraints on large DM annihilation cross sections from the early Universe Fabio Iocco Institut de Physique Theorique, CEA/Saclay Institut d’Astrophysique de Paris In collaboration with: G. Bertone, M. Cirelli, S. Galli, A. Melchiorri, P. Panci TeVPA, SLAC 7/14/09

  2. Self-annihilating DM and the IGM Main effect of injected energy: heating and ionization of the IGM The smooth DM component annihilates with a rate (per volume) depositing energy in the gas (IGM) at a rate free e- The only DM parameter is About “ f ”, in Satyer’s talk [Galli et al. 09]

  3. Structure formation “boosts” DM annihilation Smooth component Structure component Structure formation history (Press-Schechter / Sheth-Tormen) DM density halo profile Burkert / Einasto / NFW Structure formation starts at z ~ 150 with minihalos of Earth mass 10-6 Msun

  4. Structure boost: parameter dependence Mmin=Mfs(?) Cvir(M) = ? [CIP 09] [Maccio’ et al 08] and others [Hutzi et al. 09] [Pieri et al. 08]

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

  6. A quick view on “Reionization”  Ionized: Ly- free to pass by Neutral: Ly- absorber Completely ionized IGM z ~ 6 z

  7. constraints(annihilation from structures can overproduce free e-) [Belikov & Hooper 09] [CIP 09] To be integrated! In this models: no astrophysical sources Extra-conservative bounds! [CIP 09]

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

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

  10. Combining the constraints gammas +   + IGM temperature channel NFW profile [CIP 09] [Hutzi et al. 09]

  11. Down to thermalcross-section! [Galli et al. 09] + [Slatyer et al. 09] z [CIP 09]

  12. Concluding Early Universe astrophysical observables can constrain DM properties The constraints are strong, competitive with local Universe ones (astroph. uncertainties) (getting to thermal value of <v>!!!) Going technical Can we reionize the Universe with DM? Yes we can! AND it is not structures to do it: smooth, cold component (getting rid of astro-simulation uncertainties, too)

  13. Einasto ee   NFW  ee   ee Burkert 

  14. Einasto tt WW bb tt WW bb NFW tt WW bb Burkert

  15. 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

  16. Self-annihilating DM and the CMB DM annihilation indirect, SZ by “additional” e- z>1000 there are many e- no effects Energy injection is small Modifying TT, TE, EE with additional e- (by DM annih) Letting pann free parameter [Galli et al. 09]

  17. A little more about “ f ”(coupling DM induced shower to IGM) [Slatyer et al. 09] [Slatyer et al. 09] “Opacity window” of the Universe Photoionization, IC scattering, pair production (on CMB  and matter), scattering “ f ” is DM model-dependent: type of secondaries is important!

  18. Evaluating “ f ” All channels, all secondaries, redshift dependence quarks leptons Branching ratio of DM annihilation essential for determining absorption Little reminder: Pamela is leptophilic from greek: “it likes it small” XDM => e XDM =>  [Slatyer et al. 09]

  19. Constraining DM with CMB [Galli et al. 09] + [Slatyer et al. 09]

  20. Constraining SE with CMB Sommerfeld enhancement Yukawa potential a benchmark model zr=1000, 10-8 Sommerfeld saturated [Galli et al. 09]

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