We have studied the long-term X-ray light curve (2−10 keV) of the luminous
Seyfert 1 galaxy MCG-2-58-22 by compiling data, from various X-ray satellites,
which together cover more than 20 years. We have found two distinct types of
time variations in the light curve. One is a gradual and secular decrease of
the X-ray flux, and the other is the episodic increase of X-ray flux (or flare)
by a factor of 2−4 compared with the level expected from the secular
variation. We detected 3 such flares in total; a representative duration for
the flares is ∼2 years, with intervening quiescent intervals lasting
∼6−8 years. We discuss a few possible origins for these variabilities.
Though a standard disk instability theory may explain the displayed time
variability in the X-ray light curve, the subsequent accretions of stellar
debris, from a tidal disruption event caused by a supermassive black hole in
MCG-2-58-22, cannot be ruled out as an alternative explanation.Comment: 11 pages, 1 eps figure, accepted for publication in Journal of the
Korean Astronomical Society(JKAS
