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arXiv 0901.1656astro-ph.GA
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解开半人马座A的环核环境:I。高分辨率分子气体成像

Disentangling the circumnuclear environs of Centaurus A: I. High resolution molecular gas imaging

D. Espada, S. Matsushita, A. Peck, C. Henkel, D. Iono, F. P. Israel, S. Muller, G. Petitpas, Y. Pihlstroem, G. B. Taylor, Dinh-V-Trung

摘要:

我们给出了用SMA观测到的NGC 5128(半人马座A)中心1'(1 kpc)的12 CO(2-1)发射的高分辨率图像。我们首次阐明了该区域分子气体的分布和运动学,分辨率为6 '.0 × 2'.4(100 pc × 40 pc)。我们在空间上分辨了内部24“x 12”(400 pc x 200 pc)的环核分子气体,它沿着位置角P.A. = 155度,垂直于无线电/X射线射流。环核气体的SE和NW分量与在较大半径处发现的分子气体有关。这种气体在P.A.呈现为两条平行的细丝。= 120度,这是coextensive与3千秒差距的形状的长边先前观察到的尘埃连续,以及电离和纯旋转H2线。空间和运动学的不对称性是明显的,在环核和外部气体,这表明非共面和/或非圆形运动。我们扩展到内半径(r < 200 pc)以前研究的翘曲盘模型建立再现中央平行四边形结构。采用翘曲盘模型,我们将证实在半径r = 200 - 800 pc(12“-50”)之间的发射间隙,正如以前所建议的那样。虽然这个模型解释了这个突出的特征,但是,我们的12 CO(2-1)观测结果显示了与这个模型的相关偏差。也就是说,环核气体与较大半径处的气体之间的物理联系,平行四边形特征上较亮的东南和西北侧,以及其长边的外曲率。总的来说,它更接近S形形态,这一趋势也在其他分子物种中发现。因此,我们探索定性的弱双对称的潜力,自然会解释这些特点可能的贡献。

英文摘要:

We present high resolution images of the 12CO(2-1) emission in the central 1' (1 kpc) of NGC 5128 (Centaurus A), observed using the SMA. We elucidate for the first time the distribution and kinematics of the molecular gas in this region with a resolution of 6'.0 x 2'.4 (100 pc x 40 pc). We spatially resolve the circumnuclear molecular gas in the inner 24'' x 12'' (400 pc x 200 pc), which is elongated along a position angle P.A. = 155 deg and perpendicular to the radio/X-ray jet. The SE and NW components of the circumnuclear gas are connected to molecular gas found at larger radii. This gas appears as two parallel filaments at P.A. = 120 deg, which are coextensive with the long sides of the 3 kiloparsec parallelogram shape of the previously observed dust continuum, as well as ionized and pure rotational H2 lines. Spatial and kinematical asymmetries are apparent in both the circumnuclear and outer gas, suggesting non-coplanar and/or non-circular motions. We extend to inner radii (r < 200 pc) previously studied warped disk models built to reproduce the central parallelogram-shaped structure. Adopting the warped disk model we would confirm a gap in emission between the radii r = 200 - 800 pc (12'' - 50''), as has been suggested previously. Although this model explains this prominent feature, however, our 12CO(2-1) observations show relevant deviations from this model. Namely, the physical connection between the circumnuclear gas and that at larger radii, brighter SE and NW sides on the parallelogram-shaped feature, and an outer curvature of its long sides. Overall it resembles more closely an S-shaped morphology, a trend that is also found in other molecular species. Hence, we explore qualitatively the possible contribution of a weak bi-symmetric potential which would naturally explain these peculiarities.

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