Notes from March 15 telecon on science requirements for clusters/high-ell

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  • Topic 1: sigma8(z)
    • ACTION: Change figures to sigma8(z) (Mat)
    • ACTION: Apply courser binning (e.g., dz=0.2 at low z) and even larger at z>~1.5 to keep uncertainty band flat around 1% (Nick & Mat)
    • ACTION: Figure with ratio of constraints: (T+P)/P (Mat)
    • ACTION: Overlay curves from dark energy and modified gravity models; hope to identify models we can eliminate primarily thanks to the higher z bins in CMB-S4. (Steve, David R. et al.)
    • Can we identify a well-motivated Gamma constraint that is best met with higher z constraints? ACTION: Simone et al. will look into it.
  • Topic 2: Feedback/environment
    • a) David suggested simple prescription for estimating the effect of baryons on the matter power spectrum by assuming that if baryons differ in spatial distribution, then that difference propagates as a ~10% effect on the total matter power spectrum (OmB/OmM). The need to constrain their effect on matter power spectrum to sub% levels for Stage-IV dark energy surveys then translates into a constraint on how well we have to know the relative baryon-total matter distribution using CMB-S4. ACTION: David and Colin will try to put numbers to this for a science requirement by Friday.
    • b) Emphasize that feedback is the central question facing galaxy formation models and that CMB-S4 can make a unique contribution. See if we can formulate the science requirement in terms of the advance that CMB-S4 will make over Stage-3 CMB experiments. ACTION: find expected constraints on feedback for AdvACT, SPT-3G, SO (Nick, Colin, Matt, ?)
  • Topic 3: kSZ & reionization
    • kSZ best at constraining duration of reionization. Standard numbers exist for this. It was generally agreed that this requirement would not drive the instrument design; Tom mentioned that a science requirement doesn't have to. ACTION: write down the standard numbers needed for this (Nick, Simone et al.).

Report to CDT scheduled for Friday, March 17th.