Direct Detection of Cold Flows of Dark Matter

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Direct Detection of Cold Flows of Dark Matter

• Ling Fu-Sin Rencontres de Moriond, March 18th
  2005
• in coll. with Pierre Sikivie Stuart Wick,
• Phys. Rev. D66, 023504 (2002) (astro-ph/0203448)
• astro-ph/0405231

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Outline

• Motivations
• Solar wakes
• Axion signal modulation
• WIMP signal modulation
• Conclusions

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Motivations

• DM is characterized by two essential properties
• It is collisionless
• It has negligible velocity dispersion
• Axions
• WIMPs
• Selfsimilar halos signatures

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Solar wakes
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Effect of the Suns gravity on the structure of
cold DM flows

• Solar wakes 1 flow upstream, 3 flows downstream
• Appearance of caustics
• Spike line caustic on the axis of symmetry,
  downstream
• Skirt conical surface near with opening close to
  the maximum scattering angle

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b
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Impact parameter vs. polar angle
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Flows velocity

• From energy and angular momentum conservation
• with

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Flows velocity modulation (on Earth)
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Flows velocity modulationDistortion near the
spike
Flow 4
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Flows density

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Flow density modulation (on Earth)
Flow 10
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Axion Signal Modulation
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Axion detection

• Principle Photoconversion in a strong magnetic
  field
• Photon energy
• Frequency resolution of ADMX detector _at_ LLNL
  (in search mode) for
• Cavity bandwidth set by the quality factor of
  the cavity. If one octave is to be covered in one
  year, the time spent at each frequency is about
  100 sec.

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Frequency modulation

• Relativistic effects
• Jupiter other planets
• Earths gravity
• Earths rotation
• Earths orbital rotation
• Earths eccentricity
• Frequency shift on the measurement time scale

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Density modulation

• Away from spike
• Near spike
• Near skirt

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WIMP Signal Modulation
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WIMP direct detection formulas

• Detection by elastic scattering with nuclei
• Differential event rate
• Total rate
• with , ,
• Cold flow
• with ,

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The function T(E)
Cold static
June
December
Isothermal
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The WIMP Signal modulation for the Caustic ring
halo model and the DAMA result

• Caustic ring halo model self similar infall halo
  model with a large number of flows corresponding
  to particles falling in and out for the nth time
• P. Sikivie et al., PRD56(1997)1863.
• P. Sikivie, PLB567(2003).

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List of flows
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T(E) in the caustic ring halo model
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Predicted event rate modulation _at_ DAMA in the
range 2 6 keV
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Conclusions

• DM is collisionless and has negligible velocity
  dispersion. These features determine the shape of
  its signal in a detector.
• Axion narrow peak in frequency
• WIMP plateau in the differential event rate
• The presence of caustics is potentially crucial
  for DM discovery.

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• Axions Diurnal modulation enables to reconstruct
  the velocity of the DM flow. It is therefore
  crucial to include all effects to a precision
  .
• WIMPs Event rate modulation is very sensitive to
  thresholds, and can therefore be different with
  different targets. Caustic ring halo model not
  incompatible with DAMA large WIMP masses are
  favored.