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arXiv 2012.12787astro-ph.GA
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MaNGA星系气体速度色散的两种分布

Two types of distribution of the gas velocity dispersion of MaNGA galaxies

L. S. Pilyugin, I. A. Zinchenko, M. A. Lara-Lopez, Y. A. Nefedyev, J. M. Vilchez

摘要:

分析了1146个MaNGA星系的气体速度色散σ分布。我们发现,有两种类型的分布的气体速度分散在整个图像的星系:(i)909个星系的分布呈径向对称,中心有或没有sigma增强(ii)在159个星系的图像中,在中心有或没有sigma增强的情况下,沿短轴有一个sigma增强带的分布(B分布)78个星系图像中的sigma分布不能可靠地分类。我们选取了806个特征最好的星系(其中687个星系为R分布,119个星系为B分布),比较了R分布和B分布星系的性质。我们发现,B分布星系的气体速度色散σ_m的中值比R分布星系的平均值高约5 km/s。具有B分布的星系的光学半径R_25比具有相似质量的R分布的星系的光学半径平均小0.1 dex左右。因此,星系的性质与其图像中气体速度色散的分布类型有关。这表明,增强气体速度色散带的存在可以是星系特定演化(或演化中的特定阶段)的指示。

英文摘要:

The distribution of the gas velocity dispersion sigma across the images of 1146 MaNGA galaxies is analyzed. We find that there are two types of distribution of the gas velocity dispersion across the images of galaxies: (i) the distributions of 909 galaxies show a radial symmetry with or without the sigma enhancement at the center (R distribution) and (ii) distributions with a band of enhanced sigma along the minor axis in the images of 159 galaxies with or without the sigma enhancement at the center (B distribution) The sigma distribution across the images of 78 galaxies cannot be reliable classified. We select 806 galaxies with the best defined characteristics (this sample includes 687 galaxies with R distribution and 119 galaxies with B distribution) and compare the properties of galaxies with R and B distributions. We find that the median value of the gas velocity dispersion sigma_m in galaxies with B distribution is higher by around 5 km/s, on average, than that of galaxies with R distribution. The optical radius R_25 of galaxies with B distribution is lower by around 0.1 dex, on average, than that of galaxies with similar masses with R distribution. Thus the properties of a galaxy are related to the type of distribution of the gas velocity dispersion across its image. This suggests that the presence of the band of the enhanced gas velocity dispersion can be an indicator of a specific evolution (or a specific stage in the evolution) of a galaxy.

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