Context : Strong lensing studies can provide detailed mass maps of the inner regions even in dynamically active galaxy clusters .

Aims : It is shown that proper modelling of the intracluster medium , i.e .
the main baryonic component , can play an important role .
In fact , the addition of a new contribution accounting for the gas can increase the statistical significance of the lensing model .

Methods : We propose a parametric method for strong lensing analyses which exploits multi-wavelength observations .
The mass model accounts for cluster-sized dark matter halos , galaxies ( whose stellar mass can be obtained from optical analyses ) and the intracluster medium .
The gas distribution is fitted to lensing data exploiting prior knowledge from X-ray observations .
This gives an unbiased look at each matter component and allows us to study the dynamical status of a cluster .

Results : The method has been applied to AC 114 , an irregular X-ray cluster .
We find positive evidence for dynamical activity , with the dark matter distribution shifted and rotated with respect to the gas .
On the other hand , the dark matter follows the galaxy density both for shape and orientation , which hints at its collisionless nature .
The inner region ( \mathrel { \lower 2.58 pt \hbox { $ \buildrel \textstyle < \over { \scriptstyle \sim } $ } } 250 % ~ { } \mathrm { kpc } ) is under-luminous in optical bands whereas the gas fraction ( \sim 20 \pm 5 \% ) slightly exceeds typical values .
Evidence from lensing and X-ray suggests that the cluster develops in the plane of the sky and is not affected by the lensing over-concentration bias .
Despite the dynamical activity , the matter distribution seems to be in agreement with predictions from N -body simulations .
An universal cusped profile provides a good description of either the overall or the dark matter distribution whereas theoretical scaling relations seem to be nicely fitted .

Conclusions :