The X‐Ray Structure of the Pulsar Bow Shock G189.22+2.90 in the Supernova Remnant IC 443

We present a deep observation with the Chandra X-ray Observatory of theneutron star bow shock G189.22+2.90 in the supernova remnant (SNR) IC 443. Ourdata confirm the cometary morphology and central point source seen previously,but also reveal considerable new structure. Specifically, we find that theX-ray nebula consists of two distinct components: a "tongue" of bright emissionclose to the neutron star, enveloped by a larger, fainter "tail". We interpretthe tongue and tail as delineating the termination shock and the post-shockflow, respectively, as previously identified also in the pulsar bow shockG359.23-0.82 ("the Mouse"). However, for G189.22+2.90 the tongue is much lesselongated than for the Mouse, while the tail is much broader. These differencesare consistent with the low Mach number, M >~ 2, expected for a neutron starmoving through the hot gas in a SNR's interior, supporting the case for aphysical association between G189.22+2.90 and IC 443. We resolve the stand-offdistance between the star and the head of the bow shock, which allows us toestimate a space velocity for the neutron star of ~230 km/s, independent ofdistance. We detect thermal emission from the neutron star surface at atemperature of 102 +/- 22 eV, which is consistent with the age of SNR IC 443for standard neutron star cooling models. We also identify two compact knots ofhard emission located 1-2 arcsec north and south of the neutron star.Comment: 8 pages, including 3 color EPS figure. Expaneded to include new figures, plus discussion of the association between the pulsar and the supernova remnant. ApJ, in pres