Is the negative vacuum energy around galaxies a possible candidate for   dark matter?
  In this short communication we point out to the possibility that the clouds of the negative vacuum energy around galaxies may have the same effect as dark matter. These clouds amplify the force acting on the baryonic matter around galaxies changing their dynamical and kinematical properties. Inserting the density of the baryonic matter into field equations of the cosmic quaternionic field for the present time yields the negative cosmological constant which is approximately equal to the density of the baryonic matter of galaxies. Due to the effect of the negative vacuum energy on moving cosmical objects the effective total masses of galaxies assume several times larger values as their baryonic masses. 
V. Majernik