标题： 高速外流在星系暴之后持续长达10亿年，这些星系的红移z > 1且最近已停止形成恒星。 显示英文标题

标题： High-velocity outflows persist up to 1 Gyr after a starburst in recently-quenched galaxies at z > 1

摘要： 在宇宙正午时期的恒星形成星系中普遍存在高速外流，但在同一时期的被动星系中却不那么常见。 利用从UKIDSS超深巡天（UDS）中选择的z > 1星系的光学光谱，我们进行了堆叠分析，以研究沿熄火时间序列外流性质的变化。 为此，我们使用MgII（2800 Å）吸收谱线来研究外流性质与上一次主要恒星爆发（tburst）以来的时间的关系。 我们发现在恒星形成前体星系中存在高速外流（vout ~ 1400 $\pm$ 210 km/s），在最近被熄灭且tburst < 0.6 Gyr的星系中（vout ~ 990 $\pm$ 250 km/s），以及在tburst介于0.6到1 Gyr之间的较老的熄灭星系中（vout ~ 1400 $\pm$ 220 km/s）。 最古老的星系（tburst > 1 Gyr）没有明显的显著外流迹象。 我们的样本在光学观测中没有显示AGN的迹象，表明这些星系中的任何AGN都具有非常短的活动周期，并且在观测时处于“关闭”状态。 在tburst > 0.6 Gyr的老年熄灭星系中存在显著外流现象，难以用恒星爆发活动来解释，这可能表明随着恒星爆发消退，来自间歇性AGN活动的能量输入。 显示英文摘要

摘要： High-velocity outflows are ubiquitous in star-forming galaxies at cosmic noon, but are not as common in passive galaxies at the same epoch. Using optical spectra of galaxies selected from the UKIDSS Ultra Deep Survey (UDS) at z > 1, we perform a stacking analysis to investigate the transition in outflow properties along a quenching time sequence. To do this, we use MgII (2800 A) absorption profiles to investigate outflow properties as a function of time since the last major burst of star formation (tburst). We find evidence for high-velocity outflows in the star-forming progenitor population (vout ~ 1400 $\pm$ 210 km/s), for recently quenched galaxies with tburst < 0.6 Gyr (vout ~ 990 $\pm$ 250 km/s), and for older quenched galaxies with 0.6 < tburst < 1 Gyr (vout ~ 1400 $\pm$ 220 km/s). The oldest galaxies (tburst > 1 Gyr) show no evidence for significant outflows. Our samples show no signs of AGN in optical observations, suggesting that any AGN in these galaxies have very short duty cycles, and were 'off' when observed. The presence of significant outflows in the older quenched galaxies (tburst > 0.6 Gyr) is difficult to explain with starburst activity, however, and may indicate energy input from episodic AGN activity as the starburst fades.