We revisit the mass properties of the lensing cluster of galaxies MS2137-23 and assess the mutual agreement between cluster mass estimates based on strong/weak lensing , X-rays and stellar dynamics .
We perform a thorough elliptical lens modelling using arcs and their counter-images in the range 20 \lesssim R \lesssim 100 kpc and weak lensing ( 100 \lesssim R \lesssim 1000 kpc ) .
We confirm that the dark matter distribution is well consistent with an NFW profile with high concentration c \sim 11.7 \pm 0.6 . We further analyse the stellar kinematics data of with a detailed modelling of the line-of-sight velocity distribution of stars in the cD galaxy and quantify the small bias due to non-Gaussianity of the LOSVD .
After correction , the NFW lens model is unable to properly fit kinematical data and is a factor of \sim 2 more massive than suggested by X-rays analysis ( ) . The discrepancy between projected ( lensing ) and tridimensional ( X-rays , dynamics ) mass estimates is studied by assuming prolate ( triaxial ) halos with the major axis oriented toward the line-of-sight .
This model well explains the high concentration and the misalignement between stellar and dark matter components ( \Delta \psi \sim 13 ^ { \circ } ) . We then calculate the systematic and statistical uncertainties in the relative normalization between the cylindric M _ { 2 } ( < r ) and spherical M _ { 3 } ( < r ) mass estimates for triaxial halos .
These uncertainties prevent any attempt to couple 2D and 3D constraints without undertaking a complete tridimensional analysis .
Such asphericity/projection effects should be a major concern for comparisons between lensing and X-rays/dynamics mass estimates .