In a recent paper, Gurzadyan & Penrose claim to have found directions on the sky centred on which are circles of anomalously low variance in the cosmic microwave background (CMB). These features are presented as evidence for a particular picture of the very early Universe. We attempted to repeat the analysis of these authors, and we can indeed confirm that such variations do exist in the temperature variance for annuli around points in the data. However, we find that this variation is entirely expected in a sky which contains the usual CMB anisotropies. In other words, properly simulated Gaussian CMB data contain just the sorts of variations claimed. Gurzadyan & Penrose have not found evidence for pre-Big Bang phenomena, but have simply re-discovered that the CMB contains structure.
Comment on "CCC-predicted low-variance circles in CMB sky and LCDM"
在最近的预印本(“CCC-predicted low-variance circles in the CMB sky and LCDM”)中,Gurzadyan和Penrose(2011)第二次声称在WMAP数据中以低方差同心圆的形式找到了大爆炸前活动的证据。2010年11月也有同样的说法,但很快就被三个独立团体证明是错误的。罪魁祸首仅仅是Gurzadyan和Penrose的模拟基于不适当的功率谱。在最近的论文中,他们现在声称,如果模拟是基于实现特定的WMAP频谱(即,直接从天空地图测量并受宇宙方差影响的一个),但如果模拟是基于理论LCDM光谱,则不会。在这方面,我们注意到,三个独立的再分析都是基于LCDM谱的模拟,而不是观测到的WMAP谱,仅此一点就足以表明更新的声明也是不正确的。事实上,从他们的新论文中显示的图中可以明显看出,光谱仍然是不正确的,尽管与他们的第一篇论文不同。因此,Gurzadyan和Penrose的新主张与第一篇论文中的主张一样错误,并且出于同样的原因:模拟不是基于适当的功率谱。尽管这个故事没有什么实际意义,但它可能在科学社会学方面有一些重要的影响:回顾一下Gurzadyan和Penrose为编写本系列文章所做的背景文件,特别是介绍Kolmogorov统计量的文件,我们相信,人们可以找到证据表明,基于社区的开放获取裁判过程可能会更有效地拒绝不正确的结果和索赔,传…
[Abridged] An observable signature of a detectable nontrivial spatial topology of the Universe is the circles-in-the-sky in the CMB sky. In the most general search, pairs of circles with deviation from antipodality $0^\circ \leq θ\leq 169^\circ$ and radii $10^\circ \leq λ\leq 90^\circ$ were investigated, but no matching circles were found. Assuming this negative result, we examine the question as to whether there are nearly flat universes with compact topology that would give rise to circles whose observable parameters $λ$ and $θ$ fall o outside the ranges covered by this search. We derive the…
Cosmic Microwave Background (CMB) full-sky temperature data show a hemispherical asymmetry in power nearly aligned with the Ecliptic. In real space, this anomaly can be quantified by the temperature variance in the northern and southern Ecliptic hemispheres. In this context, the northern hemisphere displays an anomalously low variance while the southern hemisphere appears unremarkable (consistent with expectations from the best-fitting theory, $Λ$CDM). While this is a well established result in temperature, the low signal-to-noise ratio in current polarization data prevents a similar compariso…
We examine all-sky cosmic microwave background (CMB) temperature maps on large angular scales to compare their consistency with two scenarios: the standard inflationary quantum picture, and a distribution constrained to have a universal variance of primordial curvature perturbations on great circles. The latter symmetry is not a property of standard quantum inflation, but may be a symmetry of holographic models with causal quantum coherence on null surfaces. Since the variation of great-circle variance is dominated by the largest angular scale modes, in the latter case the amplitude and direct…
Constraints on the topology of the Universe derived from the 7-year WMAP CMB data and prospects of constraining the topology using CMB polarisation maps
Single- and double-headed odd radio circles in the LOFAR surveys
Hamburger Sternwarte, Universität Hamburg(汉堡天文台,汉堡大学);Thüringer Landessternwarte(图林根州立天文台);Universidad de Guanajuato(瓜纳华托大学);Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München(慕尼黑大学物理学院大学天文台);Department of Astronomy and Astrophysics, The University of Chicago(芝加哥大学天体物理学系);ASTRON, Netherlands Institute for Radio Astronomy(荷兰射电天文研究所 ASTRON);Anton Pannekoek Institute for Astronomy, University of Amsterdam(阿姆斯特丹大学安东·潘内克天文研究所);Department of Physics, Astronomy and Mathematics, University of Hertfordshire(赫特福德郡大学物理、天文与数学系);INAF - Istituto di Radioastronomia(意大利国家天体物理研究所射电天文研究所)
It is by now well established that the magnitude of the two-point angular-correlation function of the cosmic microwave background temperature anisotropies is anomalously low for angular separations greater than about 60 degrees. Physics explanations of this anomaly typically focus on the properties of the Universe at the surface of last scattering, relying on the fact that large-angle temperature fluctuations are dominated by the Sachs-Wolfe effect (SW). However, these fluctuations also receive important contributions from the integrated Sachs-Wolfe effect (ISW) at both early (eISW) and late (…