  A modification of the relation between axion mass and the PQ constant permits
a relaxation of the astrophysical constraints, considerably enlarging the
allowed axion parameter space. We develop this idea in this paper, discussing a
model for an {\it ultramassive} axion, which essentially represents a
supersymmetric Weinberg-Wilczek axion of the mirror world. The experimental and
astrophysical limits allow a PQ scale f_a ~ 10^4-10^6 GeV and a mass m_a ~
1MeV, which can be accessible for future experiments.
  On a phenomenological ground, such an {\it ultramassive} axion turns out to
be quite interesting. It can be produced during the gravitational collapse or
during the merging of two compact objects, and its subsequent decay into e+e-
provides an efficient mechanism for the transfer of the gravitational energy of
the collapsing system to the electron-positron plasma. This could resolve the
energy budget problem in the Gamma Ray Bursts and also help in understanding
the SN type II explosion phenomena.
