UMICH-2015: Dark Energy / Gravity / Dark Matter break-out session 3

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Key questions:

  • What frequency coverage, angular resolution and fsky is required for each one of these probes?
  • How to implement proper forecasts (dealing with systematics, parameters space to explore...)
  • How these probes compare to others (e.g. future galaxy surveys) in terms of constraints?

Diffuse SZ effects/ Mapping momentum (lead by Francesco De Bernardis):

  • Constraining reionization with kSZ power spectra: see for example recent forecasts in
  • kSZ pairwise statistics: promising with current data. It should be very powerful with CMB-S4.
  • kSZ via cross correlation with reconstructed velocity fields. As above, it's already promising with current data, compelling in the future.
  • Separating tau/v/T_e. Forecasts: What channels are most important? How much is limited by sub-mm emission? What are realistic priors (on T_e for example) from future x-rays missions?
  • SZ polarization: offers another way to constrain clusters optical depths. Plus several other nice things: CMB quadrupole vs redshift for example. The signal is small (~0.1 uK at the center of very massive clusters) but stacking approaches might work.
  • SZ polarization from transverse motion of clusters: sensitive to the transverse component of the velocity field (hence, complementary to kSZ). Potentially very interesting but even smaller than the previous effect: suppressed by (v_t/c)^2. It should have a different frequency dependence though.

Dark Matter (lead by Cora Dvorkin):


  • How do forecasts on Dark Matter annihilation change when including foregrounds? (The current constraints do not include any foreground contribution).
  • How much can we tighten the constraints on <sigmav>/m by adding prior information on As from other observables?
  • What other dark matter scenarios can we learn about from the CMB (aside from WIMP dark matter annihilation)? (baryon/dark matter interactions, a complex dark sector, dark matter scattering with neutrinos, other models?)
  • What are the degeneracies with other non-standard cosmological parameters (i.e., Neff, neutrino mass)?