我们测量的平均温度衰减宇宙微波背景（CMB）产生的SDSS DR 7光谱红移星系目录中选择的空隙，跨越红移$0<z<0.44$。我们发现，通过按每个空隙的半径缩放的补偿礼帽滤波器观察，振幅在2.6和2.9 $μK$之间的印记;我们评估了~2 $σ$处印记的统计学显著性。我们使用$N$-身体模拟来校准我们的分析。正如预期的那样，我们发现，大的空隙产生冷点的CMB通过集成的萨克斯-沃尔夫（ISW）效应。然而，我们也发现，在晕密度场的小空隙产生热点，因为他们居住在收缩，大规模的过密区域。当堆叠来自不同半径的空隙的CMB印记时，这是需要考虑的重要影响。我们已经发现，在模拟中给出最大ISW信号的相同滤波器半径也产生接近观测中的最大检测信号。然而，虽然它是低的显着性，我们测量的信号是高得多的幅度比预期的ISW的一致性$Λ$ CDM宇宙。差异也在~2 $σ$水平。我们已经证明，我们的结果是强大的对变化的阈值在很大范围内。
英文摘要：
We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the SDSS DR7 spectroscopic redshift galaxy catalog, spanning redshifts $0<z<0.44$. We find an imprint of amplitude between 2.6 and 2.9$μK$ as viewed through a compensated top-hat filter scaled to the radius of each void; we assess the statistical significance of the imprint at ~2$σ$. We make crucial use of $N$-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the Integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different radius. We have found that the same filter radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal is much higher-amplitude than expected from ISW in the concordance $Λ$CDM universe. The discrepancy is also at the ~2$σ$ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.
The integrated Sachs-Wolfe imprint of extreme structures in the cosmic web probes the dynamical nature of dark energy. Looking through typical cosmic voids, no anomalous signal has been reported. On the contrary, supervoids, associated with large-scale fluctuations in the gravitational potential, have shown potentially disturbing excess signals. In this study, we used the Jubilee ISW simulation to demonstrate how the stacked signal depends on the void definition. We found that large underdensities, with at least $\approx5$ merged sub-voids, show a peculiar ISW imprint shape with central cold s…
The Standard Cosmological Model assumes that more than 85\% of matter is in the form of collisionless and pressureless dark matter. Unstable decaying dark matter has been proposed in the literature as an extension to the standard cold dark matter model. In this paper we investigate a scenario when dark matter decays and the resultant particle moves with respect to the dark matter. A covariant hydrodynamical model is developed in which the decay is modeled by the transfer of energy-momentum between two dark dust fluid components. We parameterise the model in terms of the decay rate $Γ$ and inje…
Cosmic voids gravitationally lens the cosmic microwave background (CMB) radiation, resulting in a distinct imprint on degree scales. We use the simulated CMB lensing convergence map from the MICE N-body simulation to calibrate our detection strategy for a given void definition and galaxy tracer density. We then identify cosmic voids in DES Year 1 data and stack the Planck 2015 lensing convergence map on their locations, probing the consistency of simulated and observed void lensing signals. When fixing the shape of the stacked convergence profile to that calibrated from simulations, we find im…
Testing the imprint of non-standard cosmologies on void profiles using Monte Carlo random walks
使用蒙特卡罗随机行走的对数正态分布，我们展示了如何定性研究非标准宇宙学的空洞属性。我们将这种方法应用于f（R）修正的重力模型，并恢复（Achitouv et al. 2016）的N体模拟结果，用于空隙轮廓及其与GR的偏差。这种方法可以扩展到研究大尺度结构的其他特性，例如空隙的丰度或过密环境。我们还介绍了一种新的方法来识别宇宙网络中的空隙，只使用随机位置周围的密度波动的几个测量。该算法允许选择具有特定轮廓和半径的空隙。因此，我们可以针对f（R）和标准重力空隙轮廓之间差异较大的空隙类别。最后，我们适用于我们的空标准星系模拟目录，并讨论如何我们的空发现者的灵活性，可以用来减少系统的错误时，探测星系空关联函数的增长率。
Cosmic voids provide a unique environment to study galaxy formation and evolution. In this paper, we analyse a set of hydrodynamic zoom-in simulations of voids, to analyse in detail their inner structures. These voids were identified in a cosmological simulation and classified according to their surrounding dynamics at very large scales: whether they are in expansion or contraction at their outskirts. We study how these environments and the dynamics of voids impact the baryonic processes inside haloes and their mechanisms of formation and evolution. We find an under-abundance of processed gas …
The CMB lensing signal from cosmic voids and superclusters probes the growth of structure in the low-redshift cosmic web. In this analysis, we cross-correlated the Planck CMB lensing map with voids detected in the Dark Energy Survey Year 3 (Y3) data set ($\sim$5,000 deg$^{2}$), expanding on previous measurements that used Y1 catalogues ($\sim$1,300 deg$^{2}$). Given the increased statistical power compared to Y1 data, we report a $6.6σ$ detection of negative CMB convergence ($κ$) imprints using approximately 3,600 voids detected from a redMaGiC luminous red galaxy sample. However, the measured…
We report a $5.3σ$ detection of the gravitational lensing effect of cosmic voids from the Baryon Oscillation Spectroscopic (BOSS) Data Release 12 seen in the $Planck$ 2018 cosmic microwave background (CMB) lensing convergence map. To make this detection, we introduce new optimal techniques for void stacking and filtering of the CMB maps, such as binning voids by a combination of their observed galaxy density and size to separate those with distinctive lensing signatures. We calibrate theoretical expectations for the void-lensing signal using mock catalogs generated in a suite of 108 full-sky l…
We apply our tetrad-based approach for constructing spherically-symmetric solutions in general relativity to modelling a void, and compare it with the standard Lemaître-Tolman-Bondi (LTB) formalism. In particular, we construct models for the void observed in the direction of Draco in the WISE-2MASS galaxy survey, and a corresponding cosmic microwave background (CMB) temperature decrement in the Planck data in the same direction. We find that the present-day density and velocity profiles of the void are not well constrained by the existing data, so that void models produced from the two approac…
Astrophysical magnetic fields decay primarily via two processes namely, ambipolar diffusion and turbulence. Constraints on the strength and the spectral index of non-helical magnetic fields have been derived earlier in the literature through the effect of the above mentioned processes on the Cosmic Microwave Background (CMB) radiation. A helical component of the magnetic field is also produced in various models of magnetogenesis, which can explain larger coherence length magnetic field. In this study, we focus on studying the effects of post recombination decay of maximally helical magnetic fi…
Reionization of the cosmic neutral hydrogen by the first stars in the Universe is an inhomogeneous process which produces spatial fluctuations in free electron density. These fluctuations lead to observable signatures in cosmological probes like the cosmic microwave background (CMB). We explore the effect of the electron density fluctuations on CMB using photon-conserving semi-numerical simulations of reionization named \texttt{SCRIPT}. We show that the amplitude of the kinematic Sunyaev-Zeldovich (kSZ) and $B$-mode polarization signal depends on the patchiness in the spatial distribution of e…
Galaxy redshift surveys, such as 2dF, SDSS, 6df, GAMA and VIPERS, have shown that the spatial distribution of matter forms a rich web, known as the cosmic web. The majority of galaxy survey analyses measure the amplitude of galaxy clustering as a function of scale, ignoring information beyond a small number of summary statistics. Since the matter density field becomes highly non-Gaussian as structure evolves under gravity, we expect other statistical descriptions of the field to provide us with additional information. One way to study the non-Gaussianity is to study filaments, which evolve non…
The Cold Spot, with an unusually cold region surrounded by a hot ring, is a statistically significant anomaly in the Cosmic Microwave Background (CMB) sky. In this work we assess whether different sets of multiple subvoids based on the 2dF-VST ATLAS Cold Spot galaxy redshift survey or a collapsing cosmic texture could have produced such an anomaly through a simultaneous search for their gravitational redshift and lensing signatures on the {\it Planck} CMB temperature anisotropies. We use patches with radii $R=10^\circ$ and $R=20^\circ$ to account for the inner cold region as well as the outer …
Towards precision cosmology with Void x CMB correlations (II): Impact of mock catalogs on the Void x CMB lensing signal
Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）；Universidad de La Laguna（拉戈纳大学）；MTA–CSFK Lendület “Momentum” Large-Scale Structure (LSS) Research Group（匈牙利科学院-塞格德大学“动量”大尺度结构研究组）；Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences（孔科利天文台，匈牙利研究与创新网络地球与天文学研究中心）；CPPM, Aix-Marseille Université, CNRS/IN2P3（地中海粒子与核物理中心，艾克斯-马赛大学，法国国家科学研究中心/法国国家核与粒子物理研究所）；Princeton University（普林斯顿大学）；California Institute of Technology（加州理工学院）
研究通过分析模拟目录对Void x CMB引力透镜信号的影响，探讨了未来宇宙学约束的潜力，发现该信号对模拟目录的依赖性较低，预计罗马任务结合现有和未来CMB观测将显著提高信号噪声比。
我们利用VIMOS光谱仪对宇宙微波背景冷点进行了红移测量。冷斑的一个可能原因是在中等或低红移处由一个非常大的空隙（线性尺寸为数百Mpc）所压印的综合萨克斯-沃尔夫效应。如果<1 emission-line galaxies drawn from an I-band flux limited sample of galaxies in the direction of the cold spot shows no evidence of a gap on scales of Delta-z>在0.35<z<1处存在这样一个空洞，那么红移分布超过700 z 0.05。在较小尺度（Δ z ~0.01）上的红移分布中存在波谷，表明较小尺度的空洞可以连接朝向冷点分离几度的区域。将这种分布与从VVDS调查的宽间隔点中提取的类似大小的子样本所产生的分布进行比较，并不表明朝向冷点的红移分布是异常的，或者这些小间隙可以唯一地归因于真实的空洞。
The Integrated Sachs-Wolfe Signal from BOSS Super-Structures
宇宙结构通过综合的萨克斯-沃尔夫效应在微波背景辐射上留下印记。我们使用SDSS-III重子声学振荡巡天在红移0.43 < z < 0.65处构造了线性信号的模板图。我们在97%的置信水平下验证了这张图在普朗克CMB温度图上的印记，并与密度-温度互相关测量结果一致。使用这个ISW重建作为模板，我们调查的存在下，ISW源，并进一步研究的Granett-Neyrinck-Szapudi超空和超星系团目录的属性。我们首次对这些结构的三维密度分布进行了研究，并证明它们是重要的结构。模型拟合表明，超空是沿着视线拉长，我们建议，这种特殊的取向可以挑选出来的光度红移空间中的空洞发现算法。我们从公开的空洞和星团星表中测量了普朗克图中的平均温度分布。在试图最大限度地堆叠ISW信号，我们构建了一个新的目录的超级结构的基础上，当地的高峰和低谷的引力势。然而，我们没有发现这些结构和CMB温度之间的显着相关性。
There is substantial and growing observational evidence from the normalized luminosity density in the near-infrared that the local universe is under-dense on scales of several hundred Megaparsecs. We test whether our parameterization of the observational data of such a "void" is compatible with the latest supernovae type Ia data and with constraints from line-of-sight peculiar velocity motions of galaxy clusters with respect to the cosmic microwave background rest frame, known as the linear kinematic Sunyaev-Zel'dovich (kSZ) effect. Our study is based on the large local void (LLV) radial profi…
Cosmic voids as a probe of the nature of dark matter: simulations and galaxy survey forecasts
University of Toronto（多伦多大学）；King’s College London（伦敦国王学院）；Imperial College London（帝国理工学院）；University of Pennsylvania（宾夕法尼亚大学）；McMaster University（麦克马斯特大学）
