A multi-probe strategy to pin down the nature of gravity and dark energy

确定引力和暗能量本质的多探针策略

• 批准号: ST/L00285X/1
• 负责人: Benjamin Joachimi
• 金额: $ 27.8万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FL00285X%2F1
• 关键词: multi; probe; strategy; pin; down

The Nobel Prize in Physics 2011 was awarded to the puzzling discovery that the Universe is not only expanding, but doing so with ever increasing speed, whereas in the standard picture of cosmology it was expected to slow down. This acceleration could either be due to a new exotic matter component called dark energy which is repellent and would form the major ingredient of the cosmos. Alternatively, the laws of gravity as predicted by Einstein's general relativity may not be quite correct on cosmological scales and need to be modified.One of the best ways to pin down the properties of dark energy and test general relativity on cosmological scales is to study the large-scale distribution of matter in the Universe and its evolution, together with its gravitational interactions. In a novel approach to probe this distribution, I am going to simultaneously analyse the positions, the velocities, and the shapes of millions of distant galaxies.The clustering of galaxies in space provides a picture of the underlying matter distribution since galaxies trace the matter density. However, the picture is biased because galaxies preferentially reside in high-density regions, and this galaxy bias limits the cosmological information that can be extracted from clustering.Using galaxy velocity measurements, one can infer the coherent motions of galaxies due to the large-scale gravitational forces via so-called redshift-space distortions, causing apparent overdensities of galaxies when these are attracted by a large mass. This effect needs to be disentangled from the actual clustering of galaxies, which is again hindered by galaxy bias, so that the power of redshift-space distortions alone to constrain cosmological parameters is limited as well.General relativity predicts that large masses can deflect light rays similar to a magnifying glass - therefore the term gravitational lensing was coined for this effect. The images of distant galaxies are distorted by the gravitational lensing of the large-scale structure of the Universe between these galaxies and Earth. These 'cosmic shear' distortions directly map the intervening matter distribution, without any dependence on galaxy bias. In addition, cosmic shear also probes the geometry of the cosmos as it depends on the distances between the light sources, the lenses, and the observer. This potentially very powerful cosmological probe is plagued by intrinsic alignments of galaxy shapes which mimic the distortions characteristic of cosmic shear and hence limit the accuracy of cosmological measurements.The key to overcome the limitations of the three probes is to analyse them jointly and also include their cross-correlations into the analysis. This will lift degeneracies between parameters as for instance caused by the galaxy bias, and calibrate systematic effects such as the intrinsic alignment contamination of cosmic shear. With this technique I will obtain significantly better constraints on dark energy and the laws of gravity than from any individual probe, and the results will additionally be much less susceptible to systematic errors.This approach requires an imaging survey with excellent image quality to measure the shapes of faint and small galaxy images which overlaps with a redshift survey that allows for the accurate measurement of galaxy distances which are needed to measure clustering and redshift-space distortions. The research team that I am going to lead has access to a unique pair of such surveys. The quality and size of the joint data set is so good that I can target different types of galaxies at the same time and thus apply even more advanced techniques to eliminate systematic effects from the measurements. The joint scientific analysis will therefore yield unprecedented precision and accuracy on the properties of dark energy and the nature of gravity.

2011年诺贝尔物理学奖是因为令人困惑的发现，宇宙不仅在扩大，而且速度不断提高，而在宇宙学的标准情况下，预计会放慢速度。这种加速可能是由于一种新的外来物质成分称为暗能量，它是驱虫剂，并且会构成宇宙的主要成分。另外，爱因斯坦（Einstein）的一般相对性预测的重力定律可能在宇宙学量表上可能不是完全正确的，需要修改。一种确定深色能量和测试宇宙学量表的总体相对性的最佳方法之一是研究宇宙中物质及其进化的大规模分布以及其重力相互作用。在一种探测此分布的新方法中，我将同时分析数百万个遥远星系的位置，速度和形状。空间中星系的聚类提供了基础物质分布以来的图片，因为星系密度痕迹。 However, the picture is biased because galaxies preferentially reside in high-density regions, and this galaxy bias limits the cosmological information that can be extracted from clustering.Using galaxy velocity measurements, one can infer the coherent motions of galaxies due to the large-scale gravitational forces via so-called redshift-space distortions, causing apparent overdensities of galaxies when these are attracted by a large 大量的。这种效果需要从星系的实际聚类中解脱出来，银河系偏见再次阻碍，以便仅红移空间扭曲的力量来限制宇宙学参数也有限。一般的相对性预测，大型群体可以偏向与放大玻璃相似的光线 - 因此，该术语是重力玻璃的效果 - 从而使这种效果产生了这种效果。遥远星系的图像因这些星系和地球之间宇宙大规模结构的重力镜片而扭曲。这些“宇宙剪切”扭曲直接绘制了中间物质分布，而无需任何对星系偏差的依赖。此外，宇宙剪切还探测宇宙的几何形状，因为它取决于光源，镜头和观察者之间的距离。这种潜在的非常强大的宇宙学探测器受到星系形状的固有比对的困扰，这些探针模仿了宇宙剪切的扭曲特征，因此限制了克服宇宙探针的限制的关键是共同分析它们，还包括它们的交叉相关性。这将提高参数之间的变性，例如由星系偏置引起的，并校准系统效应，例如宇宙剪切的内在比对污染。使用这种技术，我将获得与任何个人探测器相比，对黑暗能量和重力定律的约束要好得多，而且结果还将不太容易受到系统错误的影响。这种方法需要具有出色图像质量的成像调查，以测量微弱和小的星系图像的形状，从而使近距离测量的量子均可进行精确的测量，从而可以进行精确的测量，从而可以衡量地球及其构成的构图。我要领导的研究团队可以访问一对独特的调查。联合数据集的质量和大小非常好，以至于我可以同时靶向不同类型的星系，从而采用更先进的技术来消除测量中的系统效应。因此，联合科学分析将对暗能能的性质和重力性质产生前所未有的精度和准确性。

项目成果

A KiDS weak lensing analysis of assembly bias in GAMA galaxy groups

• DOI: 10.1093/mnras/stx705
• 发表时间: 2017-03
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: A. Dvornik;M. Cacciato;K. Kuijken;M. Viola;H. Hoekstra;R. Nakajima;E. V. Uitert;M. Brouwer;A. Choi;T. Erben;I. F. Conti;D. Farrow;R. Herbonnet;C. Heymans;H. Hildebrandt;A. Hopkins;J. McFarland;P. Norberg;P. Schneider;C. Sif'on;E. Valentijn;Lingyu Wang

KiDS-i-800: Comparing weak gravitational lensing measurements from same-sky surveys

• DOI: 10.1093/mnras/sty859
• 发表时间: 2017-07
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: A. Amon;C. Heymans;D. Klaes;T. Erben;C. Blake;H. Hildebrandt;H. Hoekstra;K. Kuijken;L. Miller;C. Morrison;A. Choi;J. D. Jong;J. D. Jong;K. Glazebrook;N. Irisarri;B. Joachimi;S. Joudaki;A. Kannawadi;C. Lidman;N. Napolitano;D. Parkinson;P. Schneider;E. V. Uitert;M. Viola;C. Wolf

Multi-wavelength scaling relations in galaxy groups: a detailed comparison of GAMA and KiDS observations to BAHAMAS simulations

星系群中的多波长标度关系：GAMA 和 KiDS 观测与 BAHAMAS 模拟的详细比较

• DOI: 10.48550/arxiv.1712.05463
• 发表时间: 2017
• 作者: Jakobs A

Studying galaxy troughs and ridges using weak gravitational lensing with the Kilo-Degree Survey

• DOI: 10.1093/mnras/sty2589
• 发表时间: 2018-05
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: M. Brouwer;V. Demchenko;J. Harnois-D'eraps;Maciej Bilicki;C. Heymans;H. Hoekstra;K. Kuijken;M. Alpaslan;S. Brough;Yan-Chuan Cai;M. Costa-Duarte;A. Dvornik;T. Erben;H. Hildebrandt;B. Holwerda;P. Schneider;C. Sif'on;E. van Uitert-E.-van Uitert-2130243441

The first and second data releases of the Kilo-Degree Survey

• DOI: 10.1051/0004-6361/201526601
• 发表时间: 2015-07
• 期刊: Astronomy and Astrophysics
• 影响因子: 6.5
• 作者: J. D. Jong;G. V. Kleijn;D. Boxhoorn;H. Buddelmeijer;M. Capaccioli;Fedor I. Getman;A. Grado;E. Helmich;Zhuoyi Huang;N. Irisarri;K. Kuijken;F. L. Barbera;J. McFarland;N. Napolitano;M. Radovich;G. Sikkema;E. Valentijn;K. Begeman;M. Brescia;S. Cavuoti;A. Choi;O. Cordes;G. Covone;M. Dall’ora;H. Hildebrandt;G. Longo;R. Nakajima;M. Paolillo;E. Puddu;A. Rifatto;Crescenzo Tortora;E. V. Uitert;Axel Buddendiek;J. Harnois-D'eraps;T. Erben;M. Eriksen;C. Heymans;H. Hoekstra;B. Joachimi;T. Kitching;D. Klaes;L. Koopmans;F. Kohlinger;N. Roy;C. Sifón;P. Schneider;W. Sutherland;M. Viola;W. Vriend