JWST/MIRI对宁静黑洞X射线双星XTE J1118+480的光谱观测：对中红外辐射中喷流和环双星尘埃贡献的约束
JWST/MIRI Spectroscopy of the Quiescent Black Hole X-ray Binary XTE J1118+480: Constraints on Jet and Circumbinary Dust Contributions to the Mid-infrared Emission
- University of Michigan（密歇根大学）
- University of Nevada, Reno（内华达大学里诺分校）
- University of Nevada, Las Vegas（内华达大学拉斯维加斯分校）
- New York University Abu Dhabi（纽约大学阿布扎比分校）
- University of Zurich（苏黎世大学）
- Harvard & Smithsonian（哈佛与史密森尼学会）
- University of Oxford（牛津大学）
- University of Cape Town（开普敦大学）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
利用JWST/MIRI对宁静黑洞X射线双星XTE J1118+480进行中红外光谱和测光观测，发现其5-25微米辐射更符合环双星尘埃盘模型而非致密喷流，首次为环双星尘埃提供光谱证据。
中文摘要 AI 辅助
我们报告了JWST/MIRI对宁静状态下的黑洞X射线双星XTE J1118+480的低分辨率光谱（5-12微米）和成像（15-25微米）观测结果，其时X射线光度为亚爱丁顿光度的十亿分之一，同时进行了同期光学监测，并给出了6 GHz下4.5微央斯基的射电上限。扣除伴星贡献后，5-12微米连续谱呈弯曲状，在6微米附近发生转折；单一幂律被否定，转而支持764±9 K的黑体辐射。转折波长之外的谱指数为α=+1.21±0.36，在2σ水平上比致密喷流的平坦至略微反转的谱更陡。若解释为同步辐射，该转折意味着在数十个引力半径尺度上存在约10^4高斯的均分磁场，但15-21微米的MIRI测光数据（在光谱观测前2.6小时获取）比其外推值高30%-90%，表明存在第二个自吸收区域。单一的部分自吸收喷流谱只有在牺牲谱曲率和25.5微米上限的情况下才能达到测光值，因此稳态致密喷流虽未被排除，但不受青睐。相反，具有代表性的自洽辐照盘模型能够重现5-25微米光谱能量分布的主要特征，其中存在一个位于约5倍双星间距处、潮汐截断半径之外的直接照亮的尘埃墙，以及约10^22克量级的最小尘埃质量。这是首个支持宁静黑洞X射线双星中环双星尘埃而非喷流的光谱证据，尽管尚非结论性的。
英文摘要
We report on JWST/MIRI low-resolution spectroscopy ($5$-$12 μ$m) and imaging ($15$-$25 μ$m) of the black hole X-ray binary XTE~J1118+480 in quiescence, at an X-ray luminosity nine orders of magnitude sub-Eddington, together with contemporaneous optical monitoring and a radio upper limit of $4.5~μ$Jy at 6 GHz. With the donor subtracted, the $5$-$12 μ$m continuum is curved, turning over near $6~μ$m; a single power law is rejected in favor of a $764\pm 9$ K blackbody. Longward of the turnover the spectral index is $α= +1.21\pm0.36$, steeper at the $2σ$ level than the flat to slightly inverted spectrum of a compact jet. Interpreted as synchrotron, the turnover implies equipartition fields of $\sim$$10^{4}$ G on scales of tens of gravitational radii, but the MIRI photometry at $15$-$21~μ$m-taken $2.6$ hr before the spectrum-lies $30$-$90$ per cent above its extrapolation, suggesting a second self-absorbed zone. A single partially self-absorbed jet spectrum can reach the photometry only at the expense of the spectral curvature and the $25.5~μ$m upper limit, so a steady compact jet is disfavored, although not excluded. Representative self-consistent irradiated-disk models instead reproduce the principal features of the $5$-$25~μ$m spectral energy distribution, with a directly illuminated dust wall at $\simeq 5$ binary separations, outside the tidal-truncation radius, and a minimum dust mass of order $10^{22}$ g. This is the first spectroscopic evidence, though not yet conclusive, favoring circumbinary dust over a jet in a quiescent black hole X-ray binary.
