We present a deep observation with the Chandra X-Ray Observatory of the neutron star bow shock G189.22+2.90 in the supernova remnant (SNR) IC 443. Our data confirm the cometary morphology and central point source seen previously, but also reveal considerable new structure. Specifically, we find that the X-ray nebula consists of two distinct components: a "tongue" of bright emission close to the neutron star, enveloped by a larger, fainter "tail." We interpret the tongue and tail as delineating the termination shock and the postshock flow, respectively, as previously identified also in the pulsar bow shock G359.23-0.82 ("the Mouse"). However, for G189.22+2.90 the tongue is much less elongated than for the Mouse, while the tail is much broader. These differences are consistent with the low Mach number, M 2, expected for a neutron star moving through the hot gas in a SNR's interior, supporting the case for a physical association between G189.22+2.90 and IC 443. We resolve the standoff distance between the star and the head of the bow shock, which allows us to estimate a space velocity for the neutron star of ~230 km s-1, independent of distance. We detect thermal emission from the neutron star surface at a temperature of 102 ± 22 eV, which is consistent with the age of SNR IC 443 for standard neutron star cooling models. We also identify two compact knots of hard emission located 1''-2'' north and south of the neutron star.
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机译：我们在超新星残余（SNR）IC 443中使用中子星弓激波G189.22 + 2.90的钱德拉X射线天文台进行了深入的观察。我们的数据证实了先前看到的彗星形态和中心点源，但同时也揭示了可观的新结构。具体来说，我们发现X射线星云由两个不同的部分组成：靠近中子星的明亮发射的“舌头”，被较大的微弱的“尾巴”包围。正如先前在脉冲星弓激波G359.23-0.82（“鼠标”）中也指出的那样，我们将舌头和尾巴分别解释为表示终止电击和震后流动。但是，对于G189.22 + 2.90，舌头的伸长率要比鼠标小得多，而尾巴则要宽得多。这些差异与低马赫数M 2一致，该低马赫数M 2被期望使中子星穿过SNR内部的热气，支持G189.22 + 2.90与IC 443之间的物理关联。在恒星和弓激波头部之间的距离，这使我们可以估计中子星的空速约为230 km s-1，与距离无关。我们在102±22 eV的温度下检测来自中子星表面的热辐射，这与标准中子星冷却模型的SNR IC 443的年龄一致。我们还确定了位于中子星南北1''-2''处的两个紧凑的硬核结。
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