Title: Inference from the small scales of cosmic shear with current and future Dark Energy Survey data Show Chinese title

Title: 从当前和未来暗能量调查数据的宇宙剪切小尺度推断

Abstract: Cosmic shear is sensitive to fluctuations in the cosmological matter density field, including on small physical scales, where matter clustering is affected by baryonic physics in galaxies and galaxy clusters, such as star formation, supernovae feedback and AGN feedback. While muddying any cosmological information that is contained in small scale cosmic shear measurements, this does mean that cosmic shear has the potential to constrain baryonic physics and galaxy formation. We perform an analysis of the Dark Energy Survey (DES) Science Verification (SV) cosmic shear measurements, now extended to smaller scales, and using the Mead et al. 2015 halo model to account for baryonic feedback. While the SV data has limited statistical power, we demonstrate using a simulated likelihood analysis that the final DES data will have the statistical power to differentiate among baryonic feedback scenarios. We also explore some of the difficulties in interpreting the small scales in cosmic shear measurements, presenting estimates of the size of several other systematic effects that make inference from small scales difficult, including uncertainty in the modelling of intrinsic alignment on nonlinear scales, `lensing bias', and shape measurement selection effects. For the latter two, we make use of novel image simulations. While future cosmic shear datasets have the statistical power to constrain baryonic feedback scenarios, there are several systematic effects that require improved treatments, in order to make robust conclusions about baryonic feedback. Show Chinese abstract

Abstract: 宇宙剪切对宇宙物质密度场的波动敏感，包括在小物理尺度上，其中物质聚集受到星系和星系团中的重子物理影响，如恒星形成、超新星反馈和活动星系核反馈。 虽然这会模糊小尺度宇宙剪切测量中包含的宇宙学信息，但这意味着宇宙剪切有可能约束重子物理和星系形成。 我们对暗能量调查（DES）科学验证（SV）的宇宙剪切测量进行了分析，现在已扩展到更小的尺度，并使用Mead等人2015年的晕模型来考虑重子反馈。 尽管SV数据统计能力有限，但我们通过模拟似然分析证明，最终的DES数据将具有区分重子反馈情景的统计能力。 我们还探讨了在宇宙剪切测量中解释小尺度的一些困难，提出了几种其他系统效应的估计，这些效应使从小尺度进行推断变得困难，包括非线性尺度上固有对齐建模的不确定性、"透镜偏差"和形状测量选择效应。 对于后两种效应，我们利用了新颖的图像模拟。 虽然未来的宇宙剪切数据集具有约束重子反馈情景的统计能力，但有几个系统效应需要改进处理，以便对重子反馈得出稳健的结论。