scholarly journals Consistency relations for large-scale structures: Applications for the integrated Sachs-Wolfe effect and the kinematic Sunyaev-Zeldovich effect

2017 ◽  
Vol 606 ◽  
pp. A128 ◽  
Author(s):  
Luca Alberto Rizzo ◽  
David F. Mota ◽  
Patrick Valageas
Keyword(s):  
Power Spectrum ◽  
Equivalence Principle ◽  
Large Scale ◽  
Initial Conditions ◽  
Time Derivative ◽  
Matter Density ◽  
Microwave Background ◽  
Large Scale Structures ◽  
Cross Correlations ◽  
Scale Structures

Consistency relations of large-scale structures provide exact nonperturbative results for cross-correlations of cosmic fields in the squeezed limit. They only depend on the equivalence principle and the assumption of Gaussian initial conditions, and remain nonzero at equal times for cross-correlations of density fields with velocity or momentum fields, or with the time derivative of density fields. We show how to apply these relations to observational probes that involve the integrated Sachs-Wolfe effect or the kinematic Sunyaev-Zeldovich effect. In the squeezed limit, this allows us to express the three-point cross-correlations, or bispectra, of two galaxy or matter density fields, or weak lensing convergence fields, with the secondary cosmic microwave background distortion in terms of products of a linear and a nonlinear power spectrum. In particular, we find that cross-correlations with the integrated Sachs-Wolfe effect show a specific angular dependence. These results could be used to test the equivalence principle and the primordial Gaussianity, or to check the modeling of large-scale structures.

scholarly journals Deep learning for Sunyaev–Zel’dovich detection in Planck

2020 ◽  
Vol 634 ◽  
pp. A81
Author(s):  
V. Bonjean
Keyword(s):  
Deep Learning ◽  
Galaxy Clusters ◽  
Large Scale ◽  
Galaxy Cluster ◽  
Proof Of Concept ◽  
Microwave Background ◽  
Large Scale Structures ◽  
Hot Gas ◽  
Scale Structures ◽  
The Universe

The Planck collaboration has extensively used the six Planck HFI frequency maps to detect the Sunyaev–Zel’dovich (SZ) effect with dedicated methods, for example by applying (i) component separation to construct a full-sky map of the y parameter or (ii) matched multi-filters to detect galaxy clusters via their hot gas. Although powerful, these methods may still introduce biases in the detection of the sources or in the reconstruction of the SZ signal due to prior knowledge (e.g. the use of the generalised Navarro, Frenk, and White profile model as a proxy for the shape of galaxy clusters, which is accurate on average but not for individual clusters). In this study, we use deep learning algorithms, more specifically, a U-net architecture network, to detect the SZ signal from the Planck HFI frequency maps. The U-net shows very good performance, recovering the Planck clusters in a test area. In the full sky, Planck clusters are also recovered, together with more than 18 000 other potential SZ sources for which we have statistical indications of galaxy cluster signatures, by stacking at their positions several full-sky maps at different wavelengths (i.e. the cosmic microwave background lensing map from Planck, maps of galaxy over-densities, and the ROSAT X-ray map). The diffuse SZ emission is also recovered around known large-scale structures such as Shapley, A399–A401, Coma, and Leo. Results shown in this proof-of-concept study are promising for potential future detection of galaxy clusters with low SZ pressure with this kind of approach, and more generally, for potential identification and characterisation of large-scale structures of the Universe via their hot gas.

scholarly journals KISS: a spectrometric imager for millimetre cosmology

2020 ◽  
Vol 228 ◽  
pp. 00010 ◽  
Author(s):  
A. Fasano ◽  
M. Aguiar ◽  
A. Benoit ◽  
A. Bideaud ◽  
O. Bourrion ◽  
...  
Keyword(s):  
Large Scale ◽  
Clusters Of Galaxies ◽  
Microwave Background ◽  
Large Scale Structures ◽  
Cluster Of Galaxies ◽  
Scientific Context ◽  
Scale Structures ◽  
The Universe ◽  
Universe Evolution ◽  
Spectro Imaging

Clusters of galaxies are used to map the large-scale structures in the universe and as probe of universe evolution. They can be observed through the Sunyaev-Zel’dovich (SZ) effect. In this respect the spectro-imaging at low resolution frequency is an important tool, today, for the study of cluster of galaxies. We have developed KISS (KIDs Interferometer Spectrum Survey), a spectrometric imager dedicated to the secondary anisotropies of the Cosmic Microwave Background (CMB). The multi-frequency approach permits to improve the component separation with respect to predecessor experiments. In this paper, firstly, we provide a description of the scientific context and the state of the art of SZ observations. Secondly, we describe the KISS instrument. Finally, we show preliminary results of the ongoing commissioning campaign.

scholarly journals How complex is the cosmic web?

2019 ◽  
Vol 491 (4) ◽  
pp. 5447-5463 ◽  
Author(s):  
F Vazza
Keyword(s):  
Large Scale ◽  
Initial Conditions ◽  
Magnetic Energy ◽  
Large Scale Structures ◽  
Dominant Component ◽  
Statistical Complexity ◽  
Statistical Sense ◽  
Scale Structures ◽  
Physical Laws ◽  
The Universe

ABSTRACT The growth of large-scale cosmic structure is a beautiful exemplification of how complexity can emerge in our Universe, starting from simple initial conditions and simple physical laws. Using enzo cosmological numerical simulations, I applied tools from Information Theory (namely, ‘statistical complexity’) to quantify the amount of complexity in the simulated cosmic volume, as a function of cosmic epoch and environment. This analysis can quantify how much difficult to predict, at least in a statistical sense, is the evolution of the thermal, kinetic, and magnetic energy of the dominant component of ordinary matter in the Universe (the intragalactic medium plasma). The most complex environment in the simulated cosmic web is generally found to be the periphery of large-scale structures (e.g. galaxy clusters and filaments), where the complexity is on average ∼10–102 times larger than in more rarefied regions, even if the latter dominate the volume-integrated complexity of the simulated Universe. If the energy evolution of gas in the cosmic web is measured on a ≈100 ${\rm kpc}\, h^{-1}$ resolution and over a ≈200 $\rm Myr$ time-scale, its total complexity is in the range of $\sim 10^{16}\!-\!10^{17} \rm \,bits$, with little dependence on the assumed gas physics, cosmology, or cosmic variance.

scholarly journals Reaching small scales with low-frequency imaging: applications to the Dark Ages

2020 ◽  
Vol 379 (2188) ◽  
pp. 20190571 ◽  
Author(s):  
L. K. Morabito ◽  
J. Silk
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Initial Conditions ◽  
Low Frequency ◽  
Integration Time ◽  
Observational Constraints ◽  
The Moon ◽  
Microwave Background ◽  
Matter Power Spectrum ◽  
Density Perturbations

The initial conditions for the density perturbations in the early Universe, which dictate the large-scale structure and distribution of galaxies we see today, are set during inflation. Measurements of primordial non-Gaussianity are crucial for distinguishing between different inflationary models. Current measurements of the matter power spectrum from the cosmic microwave background only constrain this on scales up to k  ∼ 0.1 Mpc −1 . Reaching smaller angular scales (higher values of k ) can provide new constraints on non-Gaussianity. A powerful way to do this is by measuring the HI matter power spectrum at z ≳ 30 . In this paper, we investigate what values of k can be reached for the Low-Frequency Array (LOFAR), which can achieve ≲ 1″ resolution at approximately 50 MHz. Combining this with a technique to isolate the spectrally smooth foregrounds to a wedge in k ∥ – k ⊥ space, we demonstrate what values of k we can feasibly reach within observational constraints. We find that LOFAR is approximately five orders of magnitude away from the desired sensitivity, for 10 years of integration time. This article is part of a discussion meeting issue ‘Astronomy from the Moon: the next decades’.

scholarly journals Cosmological Tests of Gravity: A Future Perspective

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 506
Author(s):  
Matteo Martinelli ◽  
Santiago Casas
Keyword(s):  
Large Scale ◽  
State Of The Art ◽  
Expected Improvement ◽  
Future Perspective ◽  
Microwave Background ◽  
Large Scale Structures ◽  
Theoretical Predictions ◽  
Model Independent ◽  
Scale Structures ◽  
Tests Of Gravity

In this review, we outline the expected tests of gravity that will be achieved at cosmological scales in the upcoming decades. We focus mainly on constraints on phenomenologically parameterized deviations from general relativity, which allow to test gravity in a model-independent way, but also review some of the expected constraints obtained with more physically motivated approaches. After reviewing the state-of-the-art for such constraints, we outline the expected improvement that future cosmological surveys will achieve, focusing mainly on future large-scale structures and cosmic microwave background surveys but also looking into novel probes on the nature of gravity. We will also highlight the necessity of overcoming accuracy issues in our theoretical predictions, issues that become relevant due to the expected sensitivity of future experiments.

scholarly journals Probing the dark matter density evolution law with large scale structures

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Kamal Bora ◽  
R. F. L. Holanda ◽  
Shantanu Desai
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Large Scale ◽  
Galaxy Cluster ◽  
Matter Density ◽  
Evolution Law ◽  
Large Scale Structures ◽  
Dark Matter Density ◽  
Scale Structures ◽  
Rule Out

AbstractWe propose a new method to explore a possible departure from the standard time evolution law for the dark matter density. We looked for a violation of this law by using a deformed evolution law, given by $$\rho _c(z) \propto (1+z)^{3+\epsilon }$$ ρ c ( z ) ∝ ( 1 + z ) 3 + ϵ , and then constrain $$\epsilon $$ ϵ . The dataset used for this purpose consists of Strong Gravitational Lensing data obtained from SLOAN Lens ACS, BOSS Emission-line Lens Survey, Strong Legacy Survey SL2S, and SLACS; along with galaxy cluster X-ray gas mass fraction measurements obtained using the Chandra Telescope. Our analyses show that $$\epsilon $$ ϵ is consistent with zero within 1 $$\sigma $$ σ c.l., but the current dataset cannot rule out with high confidence level interacting models of dark matter and dark energy.

scholarly journals Large-scale structure non-Gaussianities with modal methods

2014 ◽  
Vol 11 (S308) ◽  
pp. 67-68
Author(s):  
Marcel Schmittfull
Keyword(s):  
Large Scale ◽  
Initial Conditions ◽  
3D Structure ◽  
Computational Cost ◽  
Effective Field ◽  
Modal Expansion ◽  
Large Scale Structures ◽  
Bispectrum Estimation ◽  
Scale Structures ◽  
Non Gaussian

AbstractRelying on a separable modal expansion of the bispectrum, the implementation of a fast estimator for the full bispectrum of a 3d particle distribution is presented. The computational cost of accurate bispectrum estimation is negligible relative to simulation evolution, so the bispectrum can be used as a standard diagnostic whenever the power spectrum is evaluated. As an application, the time evolution of gravitational and primordial dark matter bispectra was measured in a large suite of N-body simulations. The bispectrum shape changes characteristically when the cosmic web becomes dominated by filaments and halos, therefore providing a quantitative probe of 3d structure formation. Our measured bispectra are determined by ∼ 50 coefficients, which can be used as fitting formulae in the nonlinear regime and for non-Gaussian initial conditions. We also compare the measured bispectra with predictions from the Effective Field Theory of Large Scale Structures (EFTofLSS).

scholarly journals Planning Future Space Measurements of the CMB

1996 ◽  
Vol 168 ◽  
pp. 447-452 ◽  
Author(s):  
J.L. Puget ◽  
N. Aghanim ◽  
R. Gispert ◽  
F.R. Bouchet ◽  
E. Hivon
Keyword(s):  
Large Scale ◽  
Gravitational Instability ◽  
Microwave Background ◽  
Small Temperature ◽  
Large Scale Structures ◽  
Future Space ◽  
Density Perturbations ◽  
Small Density ◽  
Scale Structures ◽  
The Universe

A central problem in cosmology is the building and testing of a full and detailed theory for the formation of (large-scale) structures in the Universe. It is widely believed that the observed structures today grew by gravitational instability out of very small density perturbations. Such perturbations should have left imprints as small temperature anisotropies in the cosmic microwave background (CMB) radiation.

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