Spatial distribution of far-infrared emission in spiral galaxies. I. Relation with radio continuum emission.
Spatial distribution of far-infrared emission in spiral galaxies. I. Relation with radio continuum emission.
复制标题
螺旋星系中远红外发射的空间分布。
DOI：
10.1086/118524
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
T. Rengarajan
中科院分区：
文献类型：
--
作者：
Y. Mayya;T. Rengarajan
我们利用22个螺旋星系样本的高分辨率IRAS和20厘米射电连续体（RC）图像来研究星系盘中远红外（FIR）和RC发射之间的相关性。发现指数和高斯分布的组合比单一指数分布更能表示两个波段的观测强度分布。高斯分量，我们显示不是由于有限的光束分辨率的影响，在大多数星系中包含超过60%的总通量。高斯分量的优势表明，核星形成区和凸起星是两个波段发射的重要贡献者，而不是外部指数星盘。RC轮廓比FIR轮廓更平坦，导致它们远离中心的比值Q60减小。然而，在极端外围地区，Q60增加，在FIR和RC相关的散度也高于中心地区。全球Q60及其色散与星系内部的色散相匹配。这些结果表明，观测到的全球量的紧密相关反映了内部区域的过程，只有在OB恒星和相关的II型超新星控制FIR和RC发射的地方。在外围部分，旧盘状恒星对非常小的尘埃颗粒的加热提供了FIR发射的次要成分，而没有相关的RC发射。星系NGC3079的边缘显示出沿其小轴延伸的FIR和RC辐射，可能与核星爆活动有关。
We use high resolution IRAS and 20 cm radio continuum (RC) images of a sample of 22 spiral galaxies to study the correlation between the far infra-red (FIR) and RC emissions within the galactic disks. A combination of exponential and gaussian profiles rather than a single exponential profile is found to be a better representation of the observed intensity profiles in the two bands. The gaussian component, which we show is not due to the effects of limited beam-resolution, contains more than 60% of the total flux in majority of the galaxies. The dominance of the gaussian component suggests that the nuclear star forming regions and the bulge stars are more important contributors to the emission in the two bands, rather than the outer exponential stellar disks. The RC profile is flatter compared to the FIR profile, resulting in a decrease of their ratio, Q60, away from the center. However, the Q60 increases in the extreme outer parts, where the dispersion in the FIR and RC correlation is also higher than in the central regions. The global Q60 and its dispersion match those in the inner parts of the galaxies. These results imply that the observed tight correlation in the global quantities reflects processes in the inner regions only where OB stars and the associated Type II supernovae control the FIR and RC emission. In the outer parts heating of very small dust grains by the old disk stars provides a secondary component in the FIR emission, without associated RC emission. The edge-on galaxy NGC3079 shows extended FIR and RC emissions along its minor axis, probably associated with the nuclear starburst activity.