Shocks and cold fronts in merging and massive galaxy clusters: new
  detections with Chandra
  A number of merging galaxy clusters shows the presence of shocks and cold
fronts, i.e. sharp discontinuities in surface brightness and temperature. The
observation of these features requires an X-ray telescope with high spatial
resolution like Chandra, and allows to study important aspects concerning the
physics of the intra-cluster medium (ICM), such as its thermal conduction and
viscosity, as well as to provide information on the physical conditions leading
to the acceleration of cosmic rays and magnetic field amplification in the
cluster environment. In this work we search for new discontinuities in 15
merging and massive clusters observed with Chandra by using different imaging
and spectral techniques of X-ray observations. Our analysis led to the
discovery of 22 edges: six shocks, eight cold fronts and eight with uncertain
origin. All the six shocks detected have $\mathcal{M} < 2$ derived from density
and temperature jumps. This work contributed to increase the number of
discontinuities detected in clusters and shows the potential of combining
diverse approaches aimed to identify edges in the ICM. A radio follow-up of the
shocks discovered in this paper will be useful to study the connection between
weak shocks and radio relics.
