Spiral and dwarf galaxies' kinematics and optical instrumentation

我们不同研究项目的主要目标是确定螺旋和矮小星系中存在的暗物质的物理参数(例如，密度定律、总范围)。使用的方法如下。首先，根据在甚大阵列(新墨西哥)、韦斯特堡(荷兰)、澳大利亚望远镜和DRAO(彭顿，BC)获得的21厘米HI观测，有可能得出这些星系在其光学直径2至5倍以上的自转曲线，从而测量出到最后测量的速度点(运动质量)的质量。这些观测还给出了气体质量，在某些矮小星系中，气体质量有时可能比恒星质量更重要。然后，光分布(表面测光)使我们能够(使用近红外数据，例如斯皮策)来计算恒星质量。因此，运动质量和发光质量(恒星和气体)之间的差值就是暗物质成分的量度。由于质量模型对旋转曲线的上升部分非常敏感，因此从法布里-珀罗涉测量获得的高分辨率3D数据必须与内部的HI数据相结合(以避免HI数据的光束拖尾效应)。如果有人想要确定暗物质密度分布是平坦的(例如等温的)还是像冷暗物质宇宙学模拟预测的那样在内部是尖状的(例如NFW)，这一点尤其重要。为了在非常关键的内部获得尽可能高的信噪比数据，我们建立了自己的图像光子计数系统(IPCS)，称为FaNTOmM，我们不仅在Mégantic天文台的1，6米望远镜上使用，而且在加拿大-法国-夏威夷(CFHT)和欧洲南方天文台(La Silla)的3，6米望远镜上使用。第一代FaNTOmM使用的是砷化镓增强管，它的DQE为30%(这意味着可以探测到30%的入射光子)，相比之下，老式IPCS的DQE为4%-5%。我们正在研制基于L3CCD芯片的第二代相机，它应该可以提供80%的DQE&GT；。

The main goal of our different research projects is to determine the physical parameters (e.g. density laws, total extent) of the Dark Matter present in spiral and dwarf galaxies. The methodology used is the following. First, from 21cm HI observations obtained at the Very Large Array (New-Mexico), Westerbork (Holland), the Australia Telescope, and at DRAO (Penticton, BC), it is possible to derive the rotation curves of those galaxies over 2 to 5 times their optical diameters and thus to measure the mass present out to the last measured velocity point (kinematical mass). Those observations also give us the gas mass, which can sometimes be more important than the stellar mass in certain dwarf galaxies. Then, the light distribution (surface photometry) allows us to derive the stellar mass (using near infrared data, e.g. Spitzer). The difference between the kinematical mass and the luminous mass (stars & gas) is thus a measure of the Dark Matter component. Since the mass models are very sensitive to the rising part of the rotation curves, higher resolution 3D data, obtained from Fabry-Perot interferometry, must be combined to the HI data for the inner parts (to avoid the beam smearing effect of HI data). This is especially important if someone wants to determine whether the dark matter density profiles are flat (e.g. isothermal) or cuspy (e.g. NFW) in the very inner parts, as predicted by Cold Dark Matter cosmological simulations. In order to get the highest Signal-to-Noise data possible in the very critical inner parts, we built our own Image Photon Counting System (IPCS) called FaNTOmM, which we used not only on the 1,6m telescope of the Observatoire du mont Mégantic, but also on the 3,6m telescopes of the Canada-France-Hawaii (CFHT) and of the ESO (La Silla). The first generation of FaNTOmM used a GaAs intensifier tube which gives a DQE ~ 30% (meaning that 30% of the incoming photons are detected), as compared to ~4-5% for the old IPCS and we are working on the second generation camera based on a L3CCD chip which should provide a DQE > 80%.