AI 中文总结
本研究通过探测88个亮星系的CIV吸收线，发现其CGM中9个吸收体与双极极风相关，为星系外流模型提供观测支持。
AI 中文摘要
我们研究了红移z<0.03的88个孤立亮星系（L_B>0.2L*_B）的星系际介质（CGM）中的CIV 1548、1550吸收线，这些星系的选择未预先了解CGM吸收情况，具有观测上无偏的倾角和星系-类星体视线方位角分布。在静止帧等效宽度的5σ探测阈值W_r>0.1埃以上，我们在投影分离R_perp<350千秒差距的88个星系中，发现9个星系的CGM存在吸收。这9个吸收体均位于恒星形成星系（log(sSFR/yr^-1)>-10.75）的投影短轴30度范围内且R_perp<1.2R_vir。在99.998%（4.3σ）的置信水平下，我们可以排除这些吸收体来自星系-类星体方位角随机分布的可能性。这些发现为与这些当前时代星系中等升高的恒星形成相关的双极极风提供了有力证据，我们描述了支持这一假设的简单空间运动学模型。高比恒星形成率可能不是预测短轴CIV吸收的充分条件，因为恒星形成星系短轴30度范围内子样本的覆盖因子f_cov≈0.5，这可能暗示存在瞬态和/或斑块状外流。结合MgII和OVI CGM吸收的研究，我们倾向于这样一种场景：含CIV的CGM气体介于这些低电离和高电离区域之间，包含富集的中间电离云，这些云被夹带并准直在双极恒星风中，同时通过非平衡光电离混合和冷却。
英文摘要
We studied CIV 1548,1550 absorption in the circumgalactic medium (CGM) of 88 isolated, bright (L_B > 0.2L*_B) galaxies at z < 0.03 selected without prior knowledge of CGM absorption. The galaxies have observationally-unbiased distributions of inclination and galaxy-quasar sightline azimuthal angle. Above a 5-sigma rest-frame equivalent width detection threshold of W_r > 0.1 angstroms, we found absorption in the CGM of 9/88 of the galaxies within projected separation R_perp < 350 kpc. All nine absorbers arise within 30 deg of the projected minor axes and R_perp < 1.2R_vir of star-forming galaxies [log(sSFR/yr^-1) > -10.75]. To a confidence level of 99.998% (4.3-sigma), we can rule out that these absorbers are drawn from a random distribution of galaxy-quasar azimuthal angles. These findings suggest strong evidence for biconical polar winds related to the moderately elevated star formation in these present-epoch galaxies and we describe simple spatial-kinematic models that support this hypothesis. High specific star-formation rates may not be a sufficient condition for predicting minor-axis CIV absorption because the covering fraction of the subsample of star-forming galaxies within 30 deg of their minor axes is f_cov ~ 0.5; this may imply transient and/or patchy outflows. Incorporating studies of MgII and OVI CGM absorption, we favor a scenario in which CIV-bearing CGM gas interfaces between these low- and high-ionization regimes, comprising enriched intermediate-ionization clouds entrained and collimated in biconical stellar winds while mixing and cooling via non-equilibrium photoionization.
Comments8 pages, 3 figures, submitted to ApJL
