Unusual glitch activity in the RRAT J1819-1458: an exhausted magnetar?

We present an analysis of regular timing observations of the high-magnetic-field Rotating Radio Transient (RRAT) J1819$-$1458 obtained using the 64-m Parkes and 76-m Lovell radio telescopes over the past five years. During this time, the RRAT has suffered two significant glitches with fractional frequency changes of $0.6\times10^{-6}$ and $0.1\times10^{-6}$. Glitches of this magnitude are a phenomenon displayed by both radio pulsars and magnetars. However, the behaviour of J1819$-$1458 following these glitches is quite different to that which follows glitches in other neutron stars, since the glitch activity resulted in a significant long-term net decrease in the slow-down rate. If such glitches occur every 30 years, the spin-down rate, and by inference the magnetic dipole moment, will drop to zero on a timescale of a few thousand years. There are also significant increases in the rate of pulse detection and in the radio pulse energy immediately following the glitches.