Kinematics of shocks, ejecta knots, and the compact remnant of a supernova
remnant gives an insight into the nature of the progenitor and surrounding
environment. We report on a proper motion measurement of X-ray knots and rims
of the magnetar-hosting supernova remnant RCW 103. Chandra data obtained in
three epochs, 1999, 2010, and 2016 are used. We find a global deceleration of
12 knots and rims both in northern and southern regions within the last โผ24 yrs, even though its age is thought to be larger than 2 kyr. Some of them
even changed their moving directions from outward (โผ1,000 km sโ1) to
inward (โผโ2,000 km sโ1). Our findings can be explained with a
collision with a high-density medium both in the northern and southern edges of
the remnant, although the remnant may still be expanding in the wind-blown
cavity. The proper motion of the associated magnetar 1E161348โ5055 is
possibly detected with a velocity of โ500 km sโ1.Comment: 8 pages, 4 figures, accepted for publication in Ap