J. D. Soler, S. Molinari, S. C. O. Glover, R. J. Smith, R. S. Klessen, R. A. Benjamin, P. Hennebelle, J. E. G. Peek, H. Beuther, G. Edenhofer, E. Zari, C. Swiggum, C. Zucker
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引用次数: 0
摘要
我们根据距离太阳 1.25 kpc 范围内的三维尘埃密度分布模型和银河系纬度 |b| ≤ 5° 范围内的 H I 和 CO 线发射,重建了本地星际介质(ISM)的视线运动。我们使用了定向梯度直方图(HOG)方法--一种用于评估图像之间形态相关性的计算机视觉技术--来匹配不同距离的天空尘埃分布平面与原子和分子线发射。我们发现三维尘埃模型与线发射之间存在明显的相关性。我们利用这种相关性为各密度通道的尘埃分配了视线速度,并绘制了相对于本地静止标准(LSR)的本地 ISM 径向运动面图。我们发现,三维尘埃模型中的大部分物质都遵循银河系的大尺度旋转模式;然而,我们也报告了局部偏离旋转模式的情况,H I 和 CO 线发射的标准偏差分别为 10.8 和 6.6 km s-1。与这些流运动相对应的气体示踪平均动能密度大约为 0.11 和 0.04 eV/cm3。假定速度场是均匀和各向同性的,这些数值与总动能密度相差无几。这些动能值与其他能量密度大致相当,从而证实了当地 ISM 中的近等分性。然而,我们发现能量和动量超密度约为 10 倍,集中在拉德克里夫波、分裂和其他局部密度结构中。虽然我们没有发现本地旋臂对这些能量超密度产生影响的证据,但它们的分布表明,除了超新星反馈之外,大尺度效应也对太阳邻域的能量分布和动力学产生了影响。
Kinetic tomography of the Galactic plane within 1.25 kiloparsecs from the Sun
We present a reconstruction of the line-of-sight motions of the local interstellar medium (ISM) based on the combination of a model of the three-dimensional dust density distribution within 1.25 kpc from the Sun and the H I and CO line emission within Galactic latitudes |b| ≤ 5°. We used the histogram of oriented gradient (HOG) method, a computer vision technique for evaluating the morphological correlation between images, to match the plane-of-the-sky dust distribution across distances with the atomic and molecular line emission. We identified a significant correlation between the 3D dust model and the line emission. We employed this correlation to assign line-of-sight velocities to the dust across density channels and produce a face-on map of the local ISM radial motions with respect to the local standard of rest (LSR). We find that most of the material in the 3D dust model follows the large-scale pattern of Galactic rotation; however, we also report local departures from the rotation pattern with standard deviations of 10.8 and 6.6 km s−1 for the H I and CO line emission, respectively. The mean kinetic energy densities corresponding to these streaming motions are around 0.11 and 0.04 eV/cm3 from either gas tracer. Assuming homogeneity and isotropy in the velocity field, these values are within a factor of a few of the total kinetic energy density. These kinetic energy values are roughly comparable to other energy densities, thus confirming the near-equipartition in the local ISM. Yet, we identify energy and momentum overdensities of around a factor of ten concentrated in the Radcliffe Wave, the Split, and other local density structures. Although we do not find evidence of the local spiral arm’s impact on these energy overdensities, their distribution suggests the influence of large-scale effects that, in addition to supernova feedback, shape the energy distribution and dynamics in the solar neighborhood.
期刊介绍:
Astronomy & Astrophysics is an international Journal that publishes papers on all aspects of astronomy and astrophysics (theoretical, observational, and instrumental) independently of the techniques used to obtain the results.