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arXiv 0907.0016astro-ph.CO
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利用三维弱引力透镜展开物质分布

Unfolding the matter distribution using 3-D weak gravitational lensing

Patrick Simon, Andy Taylor, Jan Hartlap

摘要:

结合红移和星系形状的信息提供了新的令人兴奋的方式利用引力透镜效应研究大尺度的宇宙。一个应用是本文所探讨的物质密度分布的三维重建。我们给出了一个已经知道的3-D物质密度分布的最小方差估计,有利于薄红移片的源与样品的广泛的红移分布的最佳重建相结合的概括。我们展示了如何,在原则上,源椭圆或剪切/内在的对齐相关性的内在对齐可以容纳,虽然这些影响不是本文的重点。我们描述了一个有效和快速的方法来实现估计当代台式计算机上。给出了重建中噪声和偏差的分析估计。偏差-径向方向上的结构的扩展和移位-可以用径向PSF表示,包括由于源散粒噪声和可扩展的宽透镜内核引起的重建的限制。我们的结论是,在星系团尺度上进行三维质量密度重建是可行的,但是,对于可预见的调查,信噪比>~3阈值的地图仅限于M200>~10^14 Msol/h或7 × 10^14 Msol/h的结构,在低到中等红移(z=0.1或0.6)。然而,我们发现,一个非常大规模的密度场的严重平滑的全天空地图也可能作为重建模式的S/N朝着更大的尺度增加。该方法的未来改进可以通过包括高阶透镜信息(弯曲)来获得,这也可以实现到我们的算法中。[删节]

英文摘要:

Combining redshift and galaxy shape information offers new exciting ways of exploiting the gravitational lensing effect for studying the large scales of the cosmos. One application is the three-dimensional reconstruction of the matter density distribution which is explored in this paper. We give a generalisation of an already known minimum-variance estimator of the 3-D matter density distribution that facilitates the combination of thin redshift slices of sources with samples of broad redshift distributions for an optimal reconstruction. We show how, in principle, intrinsic alignments of source ellipticities or shear/intrinsic alignment correlations can be accommodated, albeit these effects are not the focus of this paper. We describe an efficient and fast way to implement the estimator on a contemporary desktop computer. Analytic estimates for the noise and biases in the reconstruction are given. The bias -- a spread and shift of structures in radial direction -- can be expressed in terms of a radial PSF, comprising the limitations of the reconstruction due to source shot-noise and the unavoidably broad lensing kernel. We conclude that a 3-D mass-density reconstruction on galaxy cluster scales is feasible but, for foreseeable surveys, a map with a S/N>~3 threshold is limited to structures with M200>~10^14 Msol/h, or 7x10^14 Msol/h, at low to moderate redshifts (z=0.1 or 0.6). However, we find that a heavily smoothed full-sky map of the very large-scale density field may also be possible as the S/N of reconstructed modes increases towards larger scales. Future improvements of the method can be obtained by including higher-order lensing information (flexion) which could also be implemented into our algorithm. [ABRIDGED]

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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