Collapsing objects with the same gravitational trajectory can radiate
  away different amount of energy
  We study radiation emitted during the gravitational collapse from two
different types of shells. We assume that one shell is made of dark matter and
is completely transparent to the test scalar (for simplicity) field which
belongs to the standard model, while the other shell is made of the standard
model particles and is totally reflecting to the scalar field. These two shells
have exactly the same mass, charge and angular momentum (though we set the
charge and angular momentum to zero), and therefore follow the same geodesic
trajectory. However, we demonstrate that they radiate away different amount of
energy during the collapse. This difference can in principle be used by an
asymptotic observer to reconstruct the physical properties of the initial
collapsing object other than mass, charge and angular momentum. This result has
implications for the information paradox and expands the list of the type of
information which can be released from a collapsing object.
