  Heavy vector mesons detected after a heavy ion collision are important
sources of information about the quark gluon plasma. The fraction of such
particles that survive the plasma phase and reach the detectors is related to
the dissociation degree inside the thermal medium. A consistent picture for the
thermal behavior of charmonium and bottomonium quasi-states in a thermal medium
was obtained recently using a holographic bottom up model. This model captures
the heavy flavour spectroscopy of masses and decay constants in the vacuum
(zero temperature) and is consistently extended to finite temperature. The
spectral functions that emerge provide a description of the dissociation
process in terms of the broadening of the quasi-state peaks with temperature.
  The holographic approach makes it possible to determine also the quasinormal
modes. They are gravity solutions representing the quasi-particle states in the
thermal medium, with complex frequencies related to the thermal mass and width.
The quasinormal modes for charmonium and bottomonium have been studied very
recently and a consistent description of the dissociation process was found.
  An additional factor can affect the dissociation process: strong magnetic
fields are expected to be present when the plasma is formed by non-central
heavy ion collisions. So, it is important to understand the effect of such
fields on the heavy meson dissociation scenario. Here we extend the holographic
determination of quasinormal modes for the case when magnetic fields are
present. The real and imaginary parts of the mode frequencies are determined
for different values of background $e B$ field. The associated dispersion
relations for heavy quarks moving inside the plasma are also investigated for
both $ c \bar c$ and $ b \bar b \, $.
