  In juxtaposition with the standard model of rotation powered pulsar, the
model of vibration powered magnetar undergoing quake-induced torsional Alfven
vibrations in its own ultra strong magnetic field experiencing decay is
considered. The presented line of argument suggests that gradual decrease of
frequencies (lengthening of periods) of long-periodic pulsed radiation detected
from a set of X-ray sources can be attributed to magnetic-field-decay induced
energy conversion from seismic vibrations to magneto-dipole radiation of
quaking magnetar.
