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arXiv 1707.06237astro-ph.GA
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MUSE凝视阴影:NGC 5626的高分辨率尘埃衰减曲线

MUSE stares into the shadows: the high-resolution dust attenuation curve of NGC 5626

S. Viaene, M. Sarzi, M. Baes, J. Fritz, I. Puerari

摘要:

最新一代的积分场单位摄谱仪使附近星系的三维映射更近了一步。虽然到目前为止,人们的注意力主要集中在恒星和电离气体上,但也有可能以一种新的、更完整的方式来观察尘埃。利用MUSE对NGC 5626的科学验证观测,我们绘制了这个尘埃透镜状星系中的星际物质。我们使用MUSE的分辨能力来测量光学衰减,光谱分辨率为6.25 μ m,物理尺度为0.1-1 kpc。NGC 5626的积分衰减曲线显示出平滑,比银河系和SMC衰减曲线稍陡。几个尖锐的功能叠加:我们测量较低的衰减在光谱发射线和较高的衰减钠线双峰。钠线强度和空间分辨尺度上的灰尘变红之间没有相关性。此外,连续衰减被认为是独立的巴耳末减量(跟踪电离气体衰减)。我们的模型和解释的变化,在衰减曲线的每个空间分辨率的元素的NGC 5626。我们发现,尘埃的数量和分布沿视线是高度退化的任何变化的内在消光定律。我们的分析表明,NGC 5626中的星际物质存在于一个规则且稳定的圆盘中。我们的研究结果宣扬谨慎应用简单的配方去红全球星系光谱,并强调需要更现实的尘埃几何形状时,构建这样的校正公式。

英文摘要:

The newest generation of integral field unit spectrographs brings three-dimensional mapping of nearby galaxies one step closer. While the focus up to this point was mostly on stars and ionised gas, it is also possible to look at dust in a new, more complete way. Using MUSE science verification observations of NGC 5626, we map the interstellar matter in this dusty lenticular. We use the resolving power of MUSE to measure the optical attenuation with a spectral resolution of 6.25 Å, at physical scales of 0.1-1 kpc. The integrated attenuation curve of NGC 5626 shows a smooth, slightly steeper than Milky Way and SMC attenuation curves. Several sharp features are superimposed: we measure lower attenuation at spectral emission lines and higher attenuation for the sodium line doublet. No correlation was observed between sodium line strength and reddening by dust on spatially resolved scales. Additionally, the continuum attenuation was found to be independent from the Balmer decrement (tracing ionised gas attenuation). We model and interpret the variations in the attenuation curves of each spatial resolution element of NGC 5626. We find that the amount and distribution of dust along the line-of-sight is highly degenerate with any variation in the intrinsic extinction law. Our analysis shows that the interstellar matter in NGC 5626 resides in a regular and well-settled disk. Our results preach caution in the application of simple recipes to de-redden global galaxy spectra and underlines the need for more realistic dust geometries when constructing such correction formulas.

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