Notes from April 26 telecon on science requirements for clusters/high-ell

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Attending: Matt, Nick, Elisabeth, Lindsey, Brad, Adam, Tom

Cluster cosmology: Matt and Nick presented updated vaersions of their initial fisher matrix forecasts (aka 1st generation sims, posted on the S4 website). In discussion, it was recognozed that the precision of these forecasts at high-z is lower than expected, and the gains with improving resolution also lower than expected, given the projected number of clusters. A suggestion was that they not try to solve for cosmology + all scaling relation parameters using data from a single redshift bin; rather the scaling relation constraints can use the data from all redshifts, while the data in a given bin can be used to constrain sigma8(z). Mat and Nick will explore. They are also writing this work up for publication.

Cluster cosmology: Lindsey and Sebastian's discussed their plans for their 2nd generation simulations, making y maps at different the needed frequencies. The projected timescale for this is a couple of months. The also discussed the likely availability of improved cluster mass function predictions using the new Argonne emulator (expected to be made available this summer).

Cluster cosmology: the timescale for full stage 3 simulations with full baryonic hydro, accounting fully for the covariance of observable signals, is more like a couple of years. This fits well with the parallel effort for LSST.

No significant updates but good, brief discussion on astrophysics questions including likely effectiveness of basic frequency separation techniques. 2nd generations sims discussed above can test need for e.g. priors on the radial forms for emission due to SF and AGN activity. Nick mentioned that a paper on these things in the works in the context of the Simons observatory/ACT.

We agreed to meet again in 2 weeks (Wed May 10).