Heavy dark matter and Gravitational waves
  Domain walls can form after breakdown of a discrete symmetry induced by
first-order phase transition, we study the heavy dark matter produced around
the temperature of the phase transition that yields the breakdown of a
$\mathbb{Z}_{3}$ symmetry. The generated gravitational waves by domain walls
decay is found to be able to probed by the Pulsar Timing Arrays, and the future
Square Kilometer Array.
