暗能量巡天图像中来自未探测源的噪声
天体物理仪器与方法
2020-07-29 v1 宇宙学与河外天体物理
摘要
对于采用当前 CCD 技术的地基光学成像，源与天空背景光子的泊松涨落主导噪声预算且易于估计。然而，另一噪声分量来自未探测到的恒星与星系种群的信号。通过向图像中注入人造星系，我们证明在暗能量巡天 (DES) 图像中测得的星系矩方差（用于弱引力透镜测量）显著超出泊松预测，最高达 30%，且当前软件高估了背景天空水平。通过交叉关联“空”天空区域的不同图像，我们确认存在来自未探测静态源 (US) 的显著图像噪声贡献，这些源在 DES 分辨率下平均呈轻微分辨状。将这些 US 视为平稳噪声源，我们计算了泊松噪声预期的矩协方差矩阵的修正项。修正后的协方差矩阵与在注入的 DES 图像上测得的矩方差吻合在 5% 以内。因此我们拥有一种经验方法，可在弱透镜测量中统计地考虑 US，而无需极深天空模拟。我们还发现局部天空测定可消除流量测量中的偏差，代价是少量额外但可量化的噪声。
引用
@article{arxiv.2004.05618,
title = {Noise from Undetected Sources in Dark Energy Survey Images},
author = {K. Eckert and G. M. Bernstein and A. Amara and A. Amon and A. Choi and S. Everett and D. Gruen and R. A. Gruendl and E. M. Huff and N. Kuropatkin and A. Roodman and E. Sheldon and B. Yanny and Y. Zhang and T. M. C. Abbott and M. Aguena and S. Avila and K. Bechtol and D. Brooks and D. L. Burke and A. Carnero Rosell and M. Carrasco Kind and J. Carretero and M. Costanzi and L. N. da Costa and J. De Vicente and S. Desai and H. T. Diehl and J. P. Dietrich and T. F. Eifler and A. E. Evrard and B. Flaugher and J. Frieman and J. García-Bellido and E. Gaztanaga and J. Gschwend and G. Gutierrez and W. G. Hartley and D. L. Hollowood and K. Honscheid and D. J. James and R. Kron and K. Kuehn and M. A. G. Maia and J. L. Marshall and P. Melchior and F. Menanteau and R. Miquel and R. L. C. Ogando and A. Palmese and F. Paz-Chinchón and A. A. Plazas and A. K. Romer and E. Sanchez and V. Scarpine and S. Serrano and I. Sevilla-Noarbe and M. Smith and M. Soares-Santos and E. Suchyta and M. E. C. Swanson and G. Tarle and D. Thomas and T. N. Varga and A. R. Walker and W. Wester and R. D. Wilkinson and J. Zuntz and the DES Collaboration},
journal= {arXiv preprint arXiv:2004.05618},
year = {2020}
}
备注
13 pages, 10 figures