  Recent simulations have shown that asymmetries in the ejecta distribution of
supernova remnants (SNR) can still reflect asymmetries from the initial
supernova explosion. Thus, their study provides a great means to test and
constrain model predictions in relation to the distributions of heavy elements
or the neutron star kicks, both of which are key to better understanding the
explosion mechanisms in core-collapse supernovae. The use of a novel blind
source separation method applied to the megasecond X-ray observations of the
well-known Cassiopeia A SNR has revealed maps of the distribution of the ejecta
endowed with an unprecedented level of detail and clearly separated from
continuum emission. Our method also provides a three-dimensional view of the
ejecta by disentangling the red- and blue-shifted spectral components and
associated images of the Si, S, Ar, Ca and Fe, providing insights into the
morphology of the ejecta distribution in Cassiopeia A. These mappings allow us
to thoroughly investigate the asymmetries in the heavy elements distribution
and probe simulation predictions about the neutron star kicks and the relative
asymmetries between the different elements. We find in our study that most of
the ejecta X-ray flux stems from the red-shifted component, suggesting an
asymmetry in the explosion. In addition, the red-shifted ejecta can physically
be described as a broad, relatively symmetric plume, whereas the blue-shifted
ejecta is more similar to a dense knot. The neutron star also moves directly
opposite to the red-shifted parts of the ejecta similar to what is seen with
44Ti. Regarding the morphological asymmetries, it appears that heavier elements
have more asymmetrical distributions, which confirms predictions made by
simulations. This study is a showcase of the capacities of new analysis methods
to revisit archival observations to fully exploit their scientific content.
