标题： 一个进动的分子喷流是否标志着隐匿的、正在增长的NGC1377星系中的超大质量黑洞？ 显示英文标题

标题： A precessing molecular jet signaling an obscured, growing supermassive black hole in NGC1377?

摘要： 利用高分辨率（0.25 × 0.18）的 ALMA CO 3-2 观测数据，我们研究了附近的星系 NGC1377（距离 D=21 Mpc，1"=102 pc），发现了一种高速且非常集中的核外流，我们认为这是一种分子喷流，投影长度约为 ±150 pc。 沿喷流轴线，我们观察到强烈的速度反转，投影速度从 -150 km/s 到 +150 km/s 波动。 一个简单的模型表明，分子喷流在接近天球平面的轴线上进动可以再现观测结果。 由于速度反转，难以精确限制外流气体的速度，但我们估计其速度在 240 至 850 km/s 之间，且喷流进动周期为 P=0.3-1.1 Myr。 CO 辐射在喷流方向上呈块状分布，高速（±(60 到 150 km/s)）气体中的总分子质量介于 2e6 Msun（轻喷流）和 2e7 Msun（重喷流）之间。 此外，在 NGC1377 的短轴方向上也有 CO 辐射延伸。 它占 NGC1377 总流量的 >40%，可能是一种较慢且具有宽角的分子外流，部分由分子喷流拖带。 我们讨论了分子喷流的驱动机制，并建议它可能是由非常微弱的无线电喷流驱动，或者是类似于原恒星周围的吸积盘风所驱动。 NGC1377 核心区域存在强烈的嵌入活动，我们检测到了振动激发态 HCN J=4-3 v_2=1f 的发射，这与热气体和尘埃一致。 我们在 NGC1377 中心发现了大量的 H2 柱，这可能是近期气体下落速率较高的标志。 分子喷流的动力学年龄很短（<1 Myr），这表明它可能是年轻的，且与 NGC1377 处于演化过渡阶段的观点一致。 然而，需要进一步研究来确定分子喷流的年龄、质量和它在 NGC1377 核心增长过程中扮演的角色。 显示英文摘要

摘要： With high resolution (0."25 x 0."18) ALMA CO 3-2 observations of the nearby (D=21 Mpc, 1"=102 pc), extremely radio-quiet galaxy NGC1377, we have discovered a high-velocity, very collimated nuclear outflow which we interpret as a molecular jet with a projected length of +-150 pc. Along the jet axis we find strong velocity reversals where the projected velocity swings from -150 km/s to +150 km/s. A simple model of a molecular jet precessing around an axis close to the plane of the sky can reproduce the observations. The velocity of the outflowing gas is difficult to constrain due to the velocity reversals but we estimate it to be between 240 and 850 km/s and the jet to precess with a period P=0.3-1.1 Myr. The CO emission is clumpy along the jet and the total molecular mass in the high-velocity (+-(60 to 150 km/s)) gas lies between 2e6 Msun (light jet) and 2e7 Msun (massive jet). There is also CO emission extending along the minor axis of NGC1377. It holds >40% of the flux in NGC1377 and may be a slower, wide-angle molecular outflow which is partially entrained by the molecular jet. We discuss the driving mechanism of the molecular jet and suggest that it is either powered by a very faint radio jet or by an accretion disk-wind similar to those found towards protostars. The nucleus of NGC1377 harbours intense embedded activity and we detect emission from vibrationally excited HCN J=4-3 v_2=1f which is consistent with hot gas and dust. We find large columns of H2 in the centre of NGC1377 which may be a sign of a high rate of recent gas infall. The dynamical age of the molecular jet is short (<1 Myr), which could imply that it is young and consistent with the notion that NGC1377 is caught in a transient phase of its evolution. However, further studies are required to determine the age of the molecular jet, its mass and the role it is playing in the growth of the nucleus of NGC1377.