标题： 正在行动中：一个氦再电离类星体靠近Q0302-003视线方向 显示英文标题

标题： Caught in the act: a helium-reionizing quasar near the line of sight to Q0302-003

摘要： 我们报告了在红移z=3.050±0.003处发现的一个类星体，其红移与在z=3.286背景类星体Q0302-003（位于天空上相距6.5'处）的HeII甘恩-彼得森吸收谷的黑色部分附近观测到的孤立低透明度特征高度一致。 我们探讨了由这个邻近类星体产生的HeIII电离区及其与Q0302-003视线相遇的可能模型。以其目前的亮度V=20.5和距离D=3.2百万秒差距的分离度，在它活跃时间t_Q > 10^7年的情况下，该类星体可以很好地解释Q0302-003的HeII吸收光谱中的透明度间隙。 这是首次清楚地检测到类星体对相邻视线中干预吸收的“横向”接近效应及其印记。 显示英文摘要

摘要： We report the discovery of a quasar at z=3.050+/-0.003, closely coincident in redshift with the isolated low-opacity feature seen near z~3.056 in the otherwise black portion of the HeII Gunn-Peterson absorption trough seen toward the z=3.286 background quasar Q0302-003, located 6.5' away on the sky. We explore plausible models for the HeIII ionization zone created by this neighboring quasar and its interception with the line of sight toward Q0302-003. At its present brightness of V=20.5 and separation of D=3.2 Mpc, the quasar can readily account for the opacity gap in the HeII absorption spectrum of Q0302-003, provided it has been active for t_Q > 10^7 y. This is the first clear detection of the `transverse' proximity effect and imprint of a quasar on the intervening absorption detected along an adjacent line of sight.