AI 中文总结
该研究首次利用甚长基线干涉测量数据，以SS 433为对象测量X射线双星的喷流准直轮廓，发现其喷流存在渐进准直特征，确立了SS 433是首个被约束喷流相关特性的X射线双星。
AI 中文摘要
在活动星系核（AGN）的研究中已取得显著进展，但X射线双星（XRB）中的喷流准直轮廓尚未被直接测量。本文利用甚长基线干涉测量（VLBI）数据，首次测量了某X射线双星的喷流准直轮廓，研究对象为SS 433。1995年和1998年的数据显示，接近地球的喷流呈现出约束良好的准抛物线轮廓；而2000年的喷流宽度测量中存在明显的局部振荡，无法对喷流准直轮廓进行可靠表征。不过，2000年的数据表明，喷流本征张开角在去投影后，从8×10^14 cm处的约20°逐渐减小至9×10^15 cm处的约3°，为喷流的渐进准直提供了证据。文中还给出了远离地球的喷流的宽度和张开角，但受自由-自由吸收效应限制，其解释存在局限。此外，我们测量了四个波段下与频率相关的核心位置，并推导了核心位移关系。这些结果确立了SS 433是首个被约束了喷流准直、张开角演化及核心位移关系的X射线双星。
英文摘要
While significant progress has been achieved in active galactic nuclei (AGN), jet collimation profiles in X-ray binaries (XRBs) have not been directly measured. Here we report the first measurement of jet collimation profiles in an XRB using very long baseline interferometry data from SS 433. The approaching jet exhibits a well-constrained quasi-parabolic profile in the 1995 and 1998 data, whereas the prominent local oscillations present in the 2000 jet-width measurements preclude a robust characterization of the jet collimation profile. Nevertheless, the 2000 data suggest that the intrinsic jet opening angle decreases gradually from $\sim 20^\circ$ at 8$\times 10^{14}$ cm to $\sim 3^\circ$ at $9\times 10^{15}$ cm (deprojected), providing evidence for progressive jet collimation. The width and opening angle of the receding jet are also presented, although their interpretation is limited by the free--free absorption effect. In addition, we measure the frequency-dependent core positions at four bands and derive a core-shift relation. These results establish SS 433 as the first XRB in which jet collimation, opening-angle evolution, and core-shift relation are constrained.
CommentsAccepted for publication in ApJL
