Tentative detection of galaxy spin correlations in the Tully catalog

We report a tentative detection of spin correlations in the Tully catalog of nearby galaxies. We define a simple but nontrivial spin correlation function and find an analytic estimate of it in the frame of the linear perturbation theory. Then we present the observed spin correlation signal from the Tully galaxies with error bars. The three-dimensional spin correlation turns out to be significant at the 97% confidence level, detected out to a few h(-1) Mpc. This observed correlation is consistent with the theoretical prediction based on the gravitational instability picture of galaxy formation. An analysis of systematic errors is also presented. The observed strength of correlation may be sufficient to significantly affect the blank field of weak-lensing searches.