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arXiv 0903.0313astro-ph.CO
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NGC1097的恒星和分子气体动力学：核螺旋驱动的流入

Stellar and Molecular Gas Kinematics of NGC1097: Inflow Driven by a Nuclear Spiral

R. Davies, W. Maciejewski, E. Hicks, L. Tacconi, R. Genzel, H. Engel

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accepted by ApJ
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摘要：

本文给出了NGC 1097中心320 pc区域恒星和分子气体的空间分辨分布和运动学特征。恒星连续体证实了先前报道的延伸到中央100 pc的三臂螺旋图案。恒星运动学和气体分布暗示这是由于分子旋臂中的气体和尘埃消光造成的阴影效应。分子气体运动学显示出强烈的剩余（即非圆）速度，表现为2臂运动学螺旋。线性模型表明，这是预期的视线速度模式的气体中的密度波，产生一个3臂螺旋形态。我们估计了沿手臂的流入速率。使用流体动力学模型的核螺旋，我们表明，当推导到中心区域的吸积率，外流在磁盘平面之间的武器必须考虑。对于NGC 1097，尽管沿旋臂的流入速率约为1.2Msun/yr，但中心几十秒差距的净气体吸积速率要小得多。数值模型表明，入流率可以低至~0.06Msun/yr。这足以产生每20- 1.5亿年一次的重复爆发，其规模与观测到的相似。核螺旋代表了一种机制，可以将气体送入星系的中央秒差距，气体流动可持续十亿年的时间尺度。

英文摘要：

We present spatially resolved distributions and kinematics of the stars and molecular gas in the central 320pc of NGC1097. The stellar continuum confirms the previously reported 3-arm spiral pattern extending into the central 100pc. The stellar kinematics and the gas distribution imply this is a shadowing effect due to extinction by gas and dust in the molecular spiral arms. The molecular gas kinematics show a strong residual (i.e. non-circular) velocity, which is manifested as a 2-arm kinematic spiral. Linear models indicate that this is the line-of-sight velocity pattern expected for a density wave in gas that generates a 3-arm spiral morphology. We estimate the inflow rate along the arms. Using hydrodynamical models of nuclear spirals, we show that when deriving the accretion rate into the central region, outflow in the disk plane between the arms has to be taken into account. For NGC1097, despite the inflow rate along the arms being ~1.2Msun/yr, the net gas accretion rate to the central few tens of parsecs is much smaller. The numerical models indicate that the inflow rate could be as little as ~0.06Msun/yr. This is sufficient to generate recurring starbursts, similar in scale to that observed, every 20-150Myr. The nuclear spiral represents a mechanism that can feed gas into the central parsecs of the galaxy, with the gas flow sustainable for timescales of a Gigayear.

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