  (abridged) An outburst of more than 80 individual bursts, similar to those
seen from Soft Gamma Repeaters (SGRs), was detected from the Anomalous X-ray
Pulsar (AXP) 1E 2259+586 in 2002 June. Coincident with this burst activity were
gross changes in the pulsed flux, persistent flux, energy spectrum, pulse
profile and spin down of the underlying X-ray source. We present RXTE and
XMM-Newton observations of 1E 2259+586 that show the evolution of the
aforementioned source parameters during and following this episode.
Specifically, we observe an X-ray flux increase by more than an order of
magnitude having two distinct components. The first component is linked to the
burst activity and decays within ~2 days during which the energy spectrum is
considerably harder than during the quiescent state of the source. The second
component decays over the year following the glitch according to a power law in
time with an exponent -0.22 +/- 0.01. The pulsed fraction decreased initially
to ~15% RMS, and the pulse profile changed significantly during the outburst. A
glitch was observed in 1E 2259+586 that preceded the observed burst activity. A
fraction of the glitch (~19%) recovered, although the recovery was not purely
exponential. An exponential rise of ~20% of the frequency jump with a time
scale of ~14 days results in a significantly better fit to the data, however,
contamination from a systematic drift in the phase of the pulse profile cannot
be excluded. The long-term post-glitch spin-down rate decreased in magnitude
relative to the pre-glitch value. A comparison with SGR outburst properties, a
physical interpretation of the results, and implications on the number of
magnetar candidates in our Galaxy are discussed.
