AI 中文总结
研究类星体风产生发射线蓝移所需的质量和密集程度，结合1D解析与2D数值模型，发现风要有约50$f_V$倍吸积率的质量外流率，结果不支持平滑盘风，指出风团块化或从周围介质扫起质量两种情况，还提及外流功率及相关限制。
AI 中文摘要
在明亮类星体中，C IV 1550A发射线的蓝色不对称（“蓝移”）很常见。若由风形成，这些风传输多少能量、动量和质量？我们通过考虑需经谱线形成区域供应多少质量以维持给定密度和电离态来解决此问题。用1D解析模型和2D数值模型结合，发现风要有约50$f_V$倍吸积率的质量外流率才能形成蓝移C IV线，其中$f_V\leq1$是考虑团块化的体积填充因子。结果不支持在平滑盘风中形成谱线，指向两种情况之一：要么风是团块状，所需团块因子接近热星风；要么质量从周围介质扫起，风无需团块化，磁流体动力学和辐射风可提供动量和能量源。外流功率取决于终端流速$v_\infty$的平方。若风也是BAL外流，$v_\infty\sim10,000~{\rm km~s}^{-1}$，风功率对反馈很重要。有各种限制因素缓和了结论，这促使对风驱动和团块形成物理有更好理论理解，以及对谱线形成的物理条件有更好观测约束。
英文摘要
Blue asymmetries (``Blueshifts'') in the C IV 1550A emission line are common in luminous quasars. If they are formed in winds, how much energy, momentum and mass do those winds transport? We address this question by considering how much mass must be supplied through the line-forming region to maintain a given density and ionization state. Using a combination of 1D analytic and 2D numerical models, we find that for blueshifted C IV lines to form in a wind, the wind must have mass outflow rates of $\sim 50 f_V$ times the accretion rate, where $f_V \leq 1$ is the volume filling factor accounting for clumping. Our results therefore disfavour line formation in a smooth disc wind and point towards one of two scenarios: either the wind is clumpy, with required clumping factors suggestively close to those in hot star winds; alternatively, if the mass is instead swept up from the ambient medium, the wind need not be clumpy and MHD and radiative winds can provide the original source of momentum and energy. The power of the outflow depends on the square of the terminal velocity of the flow, $v_\infty$. If the wind is also the BAL outflow, with $v_\infty \sim10,000~{\rm km~s}^{-1}$, the wind power is significant and important for feedback. There are various caveats which moderate our conclusions, motivating i) a better theoretical understanding of wind driving and clump formation physics and ii) improved observational constraints on the physical conditions where the lines are formed.
Comments12 pages, 6 figures, accepted to MNRAS
