Shell galaxies: kinematical signature of shells, satellite galaxy disruption and dynamical friction

Understand

Stellar shells observed in many giant elliptical and lenticular as well as a few spiral and dwarf galaxies presumably result from radial minor mergers of galaxies.

• We show that the line-of-sight velocity distribution of the shells has a quadruple-peaked shape.
• We found simple analytical expressions that connect the positions of the four peaks of the line profile with the mass distribution of the galaxy, namely, the circular velocity at the given shell radius and the propagation velocity of the shell.
• The analytical expressions were applied to a test-particle simulation of a radial minor merger, and the potential of the simulated host galaxy was successfully recovered.