Discovery of a young, 267 millisecond pulsar in the supernova remnant W44

We report the discovery of a 267 ms pulsar, PSR 1853+01, in the supernova remnant W44 (G34.7-0.4). The pulsar is located south of the center of W44, well within its radio shell and at the southern edge of the X-ray emission region which fills the interior of the remnant. The period derivative Ṗ ≈ 208 x 10^-15 s s^-1 leads to a characteristic age of ∼20,000 yr for the pulsar, which agrees well with the estimated age of W44 (≥ 10,000 yr). Similarly, the dispersion measure derived distance of the pulsar, ∼3.2 kpc, is almost identical with the kinematic distance of the remnant, 3.1 kpc. As expected in the case of a young pulsar, PSR 1853+01 exhibits large timing activity. These data clearly indicate that the two objects are physically related and form the sixth known pulsar-supernova remnant association. We also discuss the possibility that PSR 1853+01 and a nearby older pulsar PSR 1854+00 may have a common origin in a binary system disrupted by the explosion that produced W44.