The power spectrum of the residual rotation curve velocity as a probe of
  past mergers
  According to the $\Lambda CDM$ cosmological framework, galaxies underwent
multiple mergers in their history. In this paper we propose to use the power
spectrum of the residual fluctuations of the rotation curve velocity as a probe
of past mergers. The proposition relies on the assertion that mergers are
expected to induce large scale flows and in case of major mergers shocks are
induced as well. Instabilities of the large scale flows and shocks could
generate a large scale turbulence whose size is comparable to the galactic disk
dimensions. We develop expressions relating underlying turbulence spectral
function to the observational power spectrum of the residual of the rotation
curve velocity. This relation can be used to test whether turbulence exists in
a given galaxy. The method is applied to the regular spiral galaxy NGC3198 with
the conclusion that it underwent a minor merger about 7 Gyr ago.
