We detect the kinematic Sunyaev-Zel ’ dovich ( kSZ ) effect with a statistical significance of 4.2 \sigma by combining a cluster catalogue derived from the first year data of the Dark Energy Survey ( DES ) with CMB temperature maps from the South Pole Telescope Sunyaev-Zel ’ dovich ( SPT-SZ ) Survey .
This measurement is performed with a differential statistic that isolates the pairwise kSZ signal , providing the first detection of the large-scale , pairwise motion of clusters using redshifts derived from photometric data .
By fitting the pairwise kSZ signal to a theoretical template we measure the average central optical depth of the cluster sample , \bar { \tau } _ { e } = ( 3.75 \pm 0.89 ) \cdot 10 ^ { -3 } .
We compare the extracted signal to realistic simulations and find good agreement with respect to the signal-to-noise , the constraint on \bar { \tau } _ { e } , and the corresponding gas fraction .
High-precision measurements of the pairwise kSZ signal with future data will be able to place constraints on the baryonic physics of galaxy clusters , and could be used to probe gravity on scales \gtrsim 100 Mpc .