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Cloning Hubble Deep Fields. II. Models for Evolution by Bright Galaxy Image Transformation

机译:克隆哈勃深场。二。明亮银河系图像转换的进化模型

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In a companion paper, we outlined a methodology for generating parameter-free, model-independent "no-evolution" fields of faint galaxy images, demonstrating the need for significant evolution in the Hubble Deep Field (HDF) at faint magnitudes. Here we incorporate evolution into our procedure, by transforming the input bright galaxy images with redshift, for comparison with the HDF at faint magnitudes. Pure luminosity evolution is explored with the assumption that galaxy surface brightness evolves uniformly, at a rate chosen to reproduce the I-band counts. This form of evolution exacerbates the size discrepancy identified by our no-evolution simulations by increasing the area of a galaxy visible to a fixed isophote. Reasonable dwarf-augmented models are unable to generate the count excess invoking moderate rates of stellar evolution. A plausible fit to the counts and sizes is provided by "mass-conserving" density-evolution, consistent with small-scale hierarchical growth, in which the product of disk area and space density is conserved with redshift. Here the increased surface brightness generated by stellar evolution is accommodated by the reduced average galaxy size, for a wide range of geometries. These models are useful for calculating the rates of incompleteness and the degree of overcounting. Finally we demonstrate the potential for improvement in quantifying evolution at fainter magnitudes using the Hubble Space Telescope Advanced Camera, with its superior UV and optical performance.
机译:在随附的论文中,我们概述了一种生成微弱星系图像的无参数,与模型无关的“无进化”场的方法,表明需要在微弱的量级上对哈勃深场(HDF)进行显着演化。在这里,我们通过将输入的明亮星系图像进行红移转换,将演化过程纳入了我们的程序,以便与微弱量级的HDF进行比较。在假设银河表面亮度以选定的速率重现I波段计数的情况下均匀发展的前提下,探索了纯净的光度演化。这种演化形式通过增加固定等视线可见的星系面积,加剧了我们的无进化模拟所识别出的尺寸差异。合理的矮化扩增模型无法产生数量过多的调用,从而产生适度的恒星演化速率。通过“质量节约”密度演化提供了对数量和大小的合理拟合,这与小规模分层增长相一致,其中磁盘面积和空间密度的乘积通过红移得以保留。在这种情况下,星系演化所产生的增加的表面亮度可通过减小大范围的平均星系大小来适应。这些模型可用于计算不完整率和过度计算的程度。最后,我们展示了使用哈勃太空望远镜高级相机(其具有卓越的紫外线和光学性能)在微弱数量级上量化演化的潜力。

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