Constraints on massive neutrinos from the pairwise kinematic Sunyaev-Zel'dovich effect
We present the mean pairwise momentum of clusters, as observed through the kinematic Sunvaev-Zel'dovich (kSZ) effect, as a novel probe of massive neutrinos. We find that kSZ measurements with current and upcoming surveys will provide complementary constraints on the sum of neutrino masses from large scale structure and will improve on Planck satellite measurements of the primordial cosmic microwave background (CMB) and CMB lensing. Central to the constraints is a distinctive scale dependency of the kSZ neutrino signature on the mean pairwise momentum of clusters that we do not expect to be mirrored in systematic effects that change the overall amplitude of the signal, like the cluster optical depth. Assuming a minimal $\Lambda$CDM cosmology including massive neutrinos with Planck primordial CMB priors combined with conservative kSZ specifications, we forecast $68%$ upper limits on the neutrino mass sum of $290$ meV, $220$ meV, $96$ meV for "Stage II" (ACTPol + BOSS), "Stage III" (Advanced ACTPol + BOSS), and "Stage IV" (CMB-S4 + DESI) surveys respectively, compared to the Planck alone forecast of 540 meV. These forecasts include the ability to simultaneously constrain the neutrino mass sum and the mass-averaged optical depth of the cluster sample in each redshift bin. If the averaged optical depth of clusters can be measured with few percent accuracy and a lower limiting mass is assumed, the projected kSZ constraints improve further to $120$ meV, $90$ meV and $33$ meV (Stage II, III and IV). These forecasts represent a conservative estimate of neutrino constraints using cross-correlations of arcminute-resolution CMB measurements and spectroscopic galaxy surveys. More information relevant for neutrino constraints is available from these surveys, such as galaxy clustering, weak lensing, and CMB temperature and polarization.