# KSZ

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*** kSZ with SPECTROSCOPIC redshifts *** (Simone + Emmanuel)

This includes the "reconstructed" velocity and "pairwise momentum" estimators (which are equivalent). We show forecasts for a DESI-type spectroscopic galaxy survey with 20M galaxies over 14000 sq deg and assume full overlap. The results depend somewhat on the actual gas distribution around the tracer galaxies, whose determination is one of the goals of kSZ measurements. Here we assume to have no information on scales smaller than R_vir for a typical galaxy at z ~ 1. The results reproduce the actual S/N of current analyses. These numbers are very preliminary!

To rescale to a different area/map depth, simply rescale by and pick the new noise level.

*** kSZ with PHOTOMETRIC / NO redshift information *** (Simone + Colin) useful for LSST (both clustering and lensing), WISE, SPHEREx, etc.

Here we follow http://arxiv.org/abs/1605.02722 and show forecasts for a few S4 configurations. Again the detailed numbers depend on the actual distribution of baryons on small scales (here assumed to trace the dark matter exactly on the scales of interest). Note that this method requires very good foreground cleaning and is more sensitive to residual foregrounds than using "reconstructed velocities" or "pairwise momentum". The effective noise levels in the table below include an inflation over the raw detector noise due to component separation (for the LGMCA map, it is the actual noise in the cleaned map; for AdvACT, the inflation factor over the projected 150 GHz noise matches that in LGMCA vs Planck 143 GHz). The actual performance of this method is likely to be limited by component separation on the CMB side.

Here f_free is the free electron fraction of the tracer galaxies and parametrizes the kSZ amplitude. If f_free is known externally, this can be seen as a constrain on the growth factor with the same S/N.