*** kSZ with PHOTOMETRIC / NO redshifts information *** (Simone + Colin) useful for LSST, 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 is much more sensitive to foregrounds than using "reconstructed velocities" or "pairwise momentum", and 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.