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Constraining Dark Matter with CMB and Reionization

This analysis explores the impact of dark matter annihilation on cosmic microwave background (CMB) and reionization, providing insights into constraining dark matter properties. Various factors like DM decoupling, structure formation, and energy injection are discussed. The study emphasizes the significance of early universe observables in determining DM characteristics.

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Constraining Dark Matter with CMB and Reionization

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  1. Constraining Dark Matter with CMB and Reionization Fabio Iocco Marie Curie fellow at Institut d’Astrophysique de Paris GdR Terascale, Saclay, 31/03/10

  2. The Pamela(/Fermi/ATIC) saga(or “buzz”, see talk by J. Lavalle) 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

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

  4. 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 The only DM parameter is Evolution of free electron fraction, xe more about “ f ” later [Galli, FI, Bertone, Melchiorri `09]

  5. 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) [Galli, FI et al. `09] Letting pann free parameter

  6. A little more about “ f ”(coupling DM induced shower to IGM) “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! [Slatyer et al. `09]

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

  8. 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

  9. Structure boost: parameter dependence Mmin=Mfs(?) Cvir(M) = ? [Cirelli, FI, Panci `09] [Huetzi et al. 09] [Pieri et al 08]

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

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

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

  13. constraints(annihilation from structures can overproduce free e-) [CIP `09] To be integrated! In this models: no astrophysical sources (z > 6) Extra-conservative bounds! [CIP `09]

  14. Constraining DM with CMB PAMELA DM interpretation Thermal WIMP [Galli et al. `09]

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

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

  17. 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 DM density field (can get rid of structure formation uncertainties!) 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?

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

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

  20. Down to thermalcross-section! [Galli, FI et al. `09]

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

  22. Courtesy of L. Pieri

  23. 5.1x10-4 ≤ Z ≤ 2x106 <sv> ≤ 10-21cm3/s Looser constraint than from anisotropies [McDonald, Scherrer, Walker ‘02] [Zavala, Volgersberger, White ‘09]

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