We present new measurements of dark matter distributions in 25 X-ray luminous clusters by making a full use of the two-dimensional ( 2D ) weak lensing signals obtained from high-quality Subaru/Suprime-Cam imaging data .
Our approach to directly compare the measured lensing shear pattern with elliptical model predictions allows us to extract new information on the mass distributions of individual clusters , such as the halo ellipticity and mass centroid .
We find that these parameters on the cluster shape are little degenerate with cluster mass and concentration parameters .
By combining the 2D fitting results for a subsample of 18 clusters , the elliptical shape of dark matter haloes is detected at 7 \sigma significance level .
The mean ellipticity is found to be \langle e \rangle = \langle 1 - b / a \rangle = 0.46 \pm 0.04 ( 1 \sigma ) , which is in excellent agreement with a theoretical prediction based on the standard collisionless cold dark matter model .
The mass centroid can be constrained with a typical accuracy of \sim 20 arcseconds ( \sim 50 h ^ { -1 } kpc ) in radius for each cluster .
The mass centroid position fairly well matches the position of the brightest cluster galaxy , with some clusters showing significant offsets .
Thus the 2D shear fitting method enables to assess one of the most important systematic errors inherent in the stacked cluster weak lensing technique , the mass centroid uncertainty .
In addition , the shape of the dark mass distribution is found to be only weakly correlated with that of the member galaxy distribution or the brightest cluster galaxy .
We carefully examine possible sources of systematic errors in our measurements including the effect of substructures , the cosmic shear contamination , fitting regions , and the dilution effect , and find none of them to be significant .
Our results demonstrate the power of high-quality imaging data for exploring the detailed spatial distribution of dark matter , which should improve the ability of future surveys to conduct cluster cosmology experiments .