Coupling MOAO with integral field spectroscopy: specifications for the VLT and the E-ELT
Coupling MOAO with integral field spectroscopy: specifications for the VLT and the E-ELT
复制标题
MOAO 与积分场光谱耦合：VLT 和 E-ELT 的规格
DOI：
10.1111/j.1365-2966.2008.13808.x
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发表时间：
2008
影响因子：
4.8
通讯作者：
G. Rousset
中科院分区：
文献类型：
--
作者：
M. Puech;H. Flores;M. Lehnert;B. Neichel;T. Fusco;P. Rosati;J. Cuby;G. Rousset
阐明在宇宙时间内控制星系组装和演化的过程是所有拟议中的超大望远镜（ELT）的主要目标之一。为了在我们对这些过程的理解上取得飞跃，ELT将希望利用多目标自适应光学（MOAO）系统，该系统可以大大改善宽视场的自然视觉。我们已经开发了一个端到端的模拟，以指定的科学要求的MOAO馈电积分场摄谱仪上的8米或42米的望远镜。我们的模拟重新调整观测的本地星系或从光盘或相互作用的星系的数值模拟的结果。该代码是灵活的，因为它允许我们探索广泛的仪器参数，如能量（EE），像素大小，光谱分辨率等，对于目前的分析，我们限制自己的本地盘星系表现出简单的旋转和模拟的合并。虽然模拟的数量是有限的，我们已经试图推广我们的结果，通过引入简单的概念的“点扩散函数（PSF）的对比度”，这是光污染相邻光谱的量，我们发现驱动器在给定的空间尺度最小的EE。空间采样的选择是由“尺度耦合”驱动的。通过尺度耦合，我们指的是积分场单元（IFU）像素尺度和需要通过3D光谱恢复的特征大小之间的关系，以便了解星系及其子结构的性质。由于星系的动力学性质主要反映在它们的大尺度运动中，相对粗糙的空间分辨率足以区分旋转盘和主要合并。虽然我们使用了数量有限的形态运动学的情况下，我们的模拟表明，在42米望远镜，50 - 75 mas的IFU像素尺度的选择似乎是足够的。这样的粗采样具有降低曝光时间以达到特定信噪比以及放松MOAO系统的性能的益处。另一方面，恢复z 144星系的完整2D运动学需要高信噪比和至少34%的EE在150 mas（2个像素的75 mas）。最后，我们进行了一个类似的研究，一个假设的星系/合并在z = 1.6与MOAO馈摄谱仪为8米，并发现，在0.25弧秒的空间采样至少有30%的EE需要了解光盘和合并的性质。
Elucidating the processes that governed the assembly and evolution of galaxies over cosmic time is one of the main objectives of all of the proposed Extremely Large Telescopes (ELT). To make a leap forward in our understanding of these processes, an ELT will want to take advantage of Multi-Objects Adaptive Optics (MOAO) systems, which can substantially improve the natural seeing over a wide field of view. We have developed an end-to-end simulation to specify the science requirements of a MOAO-fed integral field spectrograph on either an 8-m or 42-m telescope. Our simulations rescale observations of local galaxies or results from numerical simulations of disc or interacting galaxies. The code is flexible in that it allows us to explore a wide range of instrumental parameters such as ensquared energy (EE), pixel size, spectral resolution, etc. For the current analysis, we limit ourselves to a local disc galaxy which exhibits simple rotation and a simulation of a merger. While the number of simulations is limited, we have attempted to generalize our results by introducing the simple concepts of 'point spread function (PSF) contrast' which is the amount of light polluting adjacent spectra which we find drives the smallest EE at a given spatial scale. The choice of the spatial sampling is driven by the 'scale-coupling'. By scale-coupling we mean the relationship between the integral field unit (IFU) pixel scale and the size of the features that need to be recovered by 3D spectroscopy in order to understand the nature of the galaxy and its substructure. Because the dynamical nature of galaxies is mostly reflected in their large-scale motions, a relatively coarse spatial resolution is enough to distinguish between a rotating disc and a major merger. Although we used a limited number of morphokinematic cases, our simulations suggest that, on a 42-m telescope, the choice of an IFU pixel scale of 50-75 mas seems to be sufficient. Such a coarse sampling has the benefit of lowering the exposure time to reach a specific signal-to-noise ratio as well as relaxing the performance of the MOAO system. On the other hand, recovering the full 2D kinematics of z ∼ 4 galaxies requires high signal-to-noise ratio and at least an EE of 34 per cent in 150 mas (2 pixels of 75 mas). Finally, we carried out a similar study for a hypothetical galaxy/merger at z = 1.6 with a MOAO-fed spectrograph for an 8 m, and find that at least an EE of 30 per cent at 0.25 arcsec spatial sampling is required to understand the nature of discs and mergers.