Three-dimensional Mapping of CDM Substructure at Submillimeter Wavelengths
Three-dimensional Mapping of CDM Substructure at Submillimeter Wavelengths
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DOI：
10.1086/452623
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发表时间：
2005-03
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影响因子：
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通讯作者：
K. T. Inoue;M. Chiba
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文献类型：
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作者：
K. T. Inoue;M. Chiba
冷暗物质（CDM）结构形成模型预测，质量约为1012 M的典型星系晕中约有5%-10%是质量为108 M的子结构。为了直接探测这种亚结构，我们建议使用具有~0.“01高角分辨率的大型亚毫米波干涉仪阵列（如计划中的阿塔卡马大型亚毫米波阵列（阿尔马））观测来自强透镜类星体宿主星系的尘埃连续辐射。为了评估其观测的可行性，我们数值模拟millilensing的一个扩展的圆形源的CDM子结构建模为一个潮汐截断奇异等温球（SIS）嵌入在一个典型的类星体星系透镜系统，B1422+231，建模为一个奇异的等温椭球（SIE）与外部恒定剪切和恒定收敛。假设角分辨率为0.″01，我们发现，如果尘埃连续谱发射区的大小和微扰点处的表面亮度梯度足够大，则可以直接测量到距巨透镜晕中心数kpc处的~108 M散射子结构的角位置。从天体测量位移的规模上的几倍10质量的一个subhalo相对于一个未扰动的macrolensed图像扰动的图像，我们可以打破subhalo质量和距离之间的退化，提供macrolensing参数是从多个图像的位置和通量确定。
The cold dark matter (CDM) structure formation model predicts that about 5%-10% of a typical galactic halo of mass ~1012 M☉ is in substructures with masses ≲108 M☉. To directly detect such substructures, we propose to observe dust continuum emission from a strongly lensed QSO host galaxy using a large submillimeter interferometer array with a high angular resolution of ~0.″01, such as the planned Atacama Large Submillimeter Array (ALMA). To assess their observational feasibility, we numerically simulate millilensing of an extended circular source by a CDM substructure modeled as a tidally truncated singular isothermal sphere (SIS) embedded in a typical QSO-galaxy lens system, B1422+231, modeled as a singular isothermal ellipsoid (SIE) with an external constant shear and a constant convergence. Assuming an angular resolution of 0.″01, we find that the angular positions of ~108 M☉ substructures at several kpc from the center of the macrolens halo can be directly measured if the size of the dust continuum emission region and the gradient of the surface brightness at the position of the perturber are sufficiently large. From the astrometric shift on a scale of a few times 10 mas of an image perturbed by a subhalo with respect to an unperturbed macrolensed image, we can break the degeneracy between subhalo mass and distance provided that macrolensing parameters are determined from positions and fluxes of multiple images.