A Molecular Einstein Ring at z = 4.12: Imaging the Dynamics of a Quasar Host Galaxy Through a Cosmic Lens
A Molecular Einstein Ring at z = 4.12: Imaging the Dynamics of a Quasar Host Galaxy Through a Cosmic Lens
复制标题
z = 4.12 处的分子爱因斯坦环：通过宇宙透镜成像类星体主星系的动力学
DOI：
10.1086/591434
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
P. Cox
中科院分区：
文献类型：
--
作者：
D. Riechers;F. Walter;B. Brewer;C. Carilli;G. Lewis;F. Bertoldi;P. Cox
我们给出了高红移类星体PSS J2322+1944(z=4.12)宿主星系中分子气体的高分辨率(0.3“)甚大阵列成像。这些观测证实了该类星体宿主星系中的分子气体(CO)被透镜成一个完整的爱因斯坦环，并揭示了该系统中的内部气体动力学。该环的直径约为1.5“，因此根据我们的观测，它是在~20个分辨率元素上采样的。通过基于模型的透镜反演，我们恢复了PSS J2322+1944类星体宿主星系中分子储存库的速度梯度。爱因斯坦环形透镜的配置使我们能够放大发射，并将比例缩小到≲1kpc。从模型重建的源中，我们发现分子气分布在5kpC的尺度上，总质量M(H2)=1.7x1010M☉。动力学质量的基本估计为mdyn=4.4×1010sin−2 I M☉，即分子气体质量的~2.5倍，黑洞质量的~30倍(假设动力学结构高度倾斜)。透镜配置还允许我们将光发射与分子气体发射联系起来，这表明活动星系核确实驻留在分子储存库内，但并不靠近分子储存库的中心。与CO的(至少部分)扰动结构一起，这表明该系统正在相互作用。这种相互作用可能是由一次重大的“湿”合并引起的，可能既为类星体提供了食物，又为该系统中680M☉Yr−1的大规模恒星爆发提供了燃料，这与最近提出的类星体活动和早期宇宙中星系组装的情景一致。
We present high-resolution (0.3″) Very Large Array imaging of the molecular gas in the host galaxy of the high-redshift quasar PSS J2322+1944 (z = 4.12). These observations confirm that the molecular gas (CO) in the host galaxy of this quasar is lensed into a full Einstein ring and reveal the internal gas dynamics in this system. The ring has a diameter of ~1.5″ and thus is sampled over ~20 resolution elements by our observations. Through a model-based lens inversion, we recover the velocity gradient of the molecular reservoir in the quasar host galaxy of PSS J2322+1944. The Einstein ring lens configuration enables us to zoom in on the emission and to resolve scales down to ≲1 kpc. From the model-reconstructed source, we find that the molecular gas is distributed on a scale of 5 kpc and has a total mass of M(H2) = 1.7 × 1010 M☉. A basic estimate of the dynamical mass gives Mdyn = 4.4 × 1010 sin−2 i M☉, that is, only ~2.5 times the molecular gas mass and ~30 times the black hole mass (assuming that the dynamical structure is highly inclined). The lens configuration also allows us to tie the optical emission to the molecular gas emission, which suggests that the active galactic nucleus does reside within, but not close to the center of, the molecular reservoir. Together with the (at least partially) disturbed structure of the CO, this suggests that the system is interacting. Such interaction, possibly caused by a major “wet” merger, may be responsible for both feeding the quasar and fueling the massive starburst of 680 M☉ yr−1 in this system, in agreement with recently suggested scenarios of quasar activity and galaxy assembly in the early universe.