Abstract:
Magnetars are young neutron stars with very strong magnetic
fields. They are detected in our
Galaxy either as soft gamma-ray repeaters or anomalous X-ray pulsars.
Soft gamma-ray repeaters are a rare type of gamma-ray transient sources that
are occasionally detected as bursters in the high-energy sky. No
optical counterpart to the gama-ray flares or the quiescent source has
yet been identified. Here we report multi-wavelength observations
of a puzzling source, SWIFT J1955091261406. We detected more
than 40 flaring episodes in the optical band over a time span of
three days, and a faint infrared flare 11 days later, after which the
source returned to quiescence. Our radio observations confirm a
Galactic nature and establish a lower distance limit of ,3.7 kpc.
We suggest that SWIFT J1955091261406 could be an isolated
magnetar whose bursting activity has been detected at optical
wavelengths, and for which the long-term X-ray emission is
short-lived. In this case, a new manifestation of magnetar activity
has been recorded and we can consider SWIFT J1955091261406 to
be a link between the ‘persistent’ soft gamma-ray repeaters/anomalous
X-ray pulsars and dim isolated neutron stars.
