AUTO- AND CROSS-CORRELATION OF PHASES OF THE WHOLE-SKY CMB AND FOREGROUND MAPS FROM THE 1-YEAR WMAP DATA

2006 ◽  
Vol 15 (08) ◽  
pp. 1283-1298 ◽  
Author(s):  
LUNG-YIH CHIANG ◽  
PAVEL D. NASELSKY
Keyword(s):  
Cross Correlation ◽  
Random Phase ◽  
Cosmological Parameters ◽  
Microwave Background ◽  
Return Mapping ◽  
Auto Correlation ◽  
Dimensional Uniformity ◽  
Cross Correlations ◽  
Wmap Data

The issue of non-Gaussianity is not only related to distinguishing the theories of the origin of primordial fluctuations, but also crucial for the determination of cosmological parameters in the framework of inflation paradigm. We present a method for testing non-Gaussianity on the whole-sky cosmic microwave background (CMB) anisotropies. This method is based on the Kuiper's statistic to probe the two-dimensional uniformity on a periodic mapping square associating phases: return mapping of phases of the derived CMB (similar to auto-correlation) and cross-correlations between phases of the derived CMB and foregrounds. Since phases reflect morphology, detection of cross-correlation of phases signifies the contamination of foreground signals in the derived CMB map. The advantage of this method is that one can cross-check the auto- and cross-correlation of phases of the derived maps and foregrounds, and mark off those multipoles in which the non-Gaussianity results from the foreground contaminations. We apply this statistic on the derived signals from the 1-year WMAP data. The auto-correlations of phases from the internal linear combination map show the significance above 95% C.L. against the random phase hypothesis on 17 spherical harmonic multipoles, among which some have pronounced cross-correlations with the foreground maps. We find that most of the non-Gaussianity found in the derived maps are from foreground contaminations. With this method we are better equipped to approach the issue of non-Gaussianity of primordial origin for the upcoming Planck mission.

Assessing Convergence in Predictions of Periodic-Unsteady Flowfields

2006 ◽  
Author(s):  
J. P. Clark ◽  
E. A. Grover
Keyword(s):  
Cross Correlation ◽  
Unsteady Flows ◽  
Digital Signal ◽  
Design Decisions ◽  
Time Resolved ◽  
Design Engineers ◽  
Cross Correlations ◽  
Parseval’S Theorem ◽  
Hot Streak

Predictions of time-resolved flowfields are now commonplace within the gas-turbine industry, and the results of such simulations are often used to make design decisions during the development of new products. Hence it is necessary for design engineers to have a robust method to determine the level of convergence in design predictions. Here we report on a method developed to determine the level of convergence in a predicted flowfield that is characterized by periodic-unsteadiness. The method relies on fundamental concepts from digital signal processing including the discrete Fourier transform, cross-correlation, and Parseval’s theorem. Often in predictions of vane-blade interaction in turbomachines, the period of the unsteady fluctuations is expected. In this method, the development of time-mean quantities. Fourier components (both magnitude and phase), cross-correlations, and integrated signal power are tracked at locations of interest from one period to the next as the solution progresses. Each of these separate quantities yields some relative measure of convergence that is subsequently processed to form a fuzzy set. Thus the overall level of convergence in the solution is given by the intersection of these sets. Examples of the application of this technique to several predictions of unsteady flows from two separate solvers are given. These include a prediction of hot-streak migration as well as more typical cases. It is shown that the method yields a robust determination of convergence. Also, the results of the technique can guide further analysis and/or post-processing of the flowfield. Finally, the method is useful for the detection of inherent unsteadiness in the flowfield, and as such it can be used to prevent design escapes.

scholarly journals Simultaneous determination of the cosmic birefringence and miscalibrated polarization angles from CMB experiments

2019 ◽  
Vol 2019 (8) ◽  
Author(s):  
Yuto Minami ◽  
Hiroki Ochi ◽  
Kiyotomo Ichiki ◽  
Nobuhiko Katayama ◽  
Eiichiro Komatsu ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Power Spectra ◽  
Microwave Background ◽  
Polarization Data ◽  
Satellite Mission ◽  
Cmb Polarization ◽  
Angle Alpha ◽  
The Difference ◽  
Polarization Spectra

Abstract We show that the cosmic birefringence and miscalibrated polarization angles can be determined simultaneously by cosmic microwave background (CMB) experiments using the cross-correlation between $E$- and $B$-mode polarization data. This is possible because the polarization angles of the CMB are rotated by both the cosmic birefringence and miscalibration effects, whereas those of the Galactic foreground emission are rotated only by the latter. Our method does not require prior knowledge of the $E$- and $B$-mode power spectra of the foreground emission, but uses only the knowledge of the CMB polarization spectra. Specifically, we relate the observed $EB$ correlation to the difference between the observed$E$- and $B$-mode spectra in the sky, and use different multipole dependences of the CMB (given by theory) and foreground spectra (given by data) to derive the likelihood for the miscalibration angle $\alpha$ and the birefringence angle $\beta$. We show that a future satellite mission similar to LiteBIRD can determine $\beta$ with a precision of 10 arcmin.

scholarly journals Cross-Correlation of Planck CMB Lensing with DESI-Like LRGs

2020 ◽  
Author(s):  
Ellie Kitanidis ◽  
Martin White
Keyword(s):  
Large Scale ◽  
Cross Correlation ◽  
Theory Model ◽  
Microwave Background ◽  
Redshift Distribution ◽  
Luminous Red Galaxies ◽  
Bias Model ◽  
Cross Correlations ◽  
Galaxy Bias ◽  
Red Galaxies

Abstract Cross-correlations between the lensing of the cosmic microwave background (CMB) and other tracers of large-scale structure provide a unique way to reconstruct the growth of dark matter, break degeneracies between cosmology and galaxy physics, and test theories of modified gravity. We detect a cross-correlation between DESI-like luminous red galaxies (LRGs) selected from DECaLS imaging and CMB lensing maps reconstructed with the Planck satellite at a significance of S/N = 27.2 over scales ℓmin = 30, ℓmax = 1000. To correct for magnification bias, we determine the slope of the LRG cumulative magnitude function at the faint limit as s = 0.999 ± 0.015, and find corresponding corrections on the order of a few percent for $C^{\kappa g}_{\ell }, C^{gg}_{\ell }$ across the scales of interest. We fit the large-scale galaxy bias at the effective redshift of the cross-correlation zeff ≈ 0.68 using two different bias evolution agnostic models: a HaloFit times linear bias model where the bias evolution is folded into the clustering-based estimation of the redshift kernel, and a Lagrangian perturbation theory model of the clustering evaluated at zeff. We also determine the error on the bias from uncertainty in the redshift distribution; within this error, the two methods show excellent agreement with each other and with DESI survey expectations.

scholarly journals Detection of Anisotropy in the Cosmic Microwave Background at Horizon and Sub-Horizon Scales with the BOOMERanG Experiment

2005 ◽  
Vol 201 ◽  
pp. 55-64
Author(s):  
P. de Bernardis ◽  
P. A. R. Ade ◽  
J. J. Bock ◽  
J. R. Bond ◽  
J. Borrill ◽  
...  
Keyword(s):  
Total Mass ◽  
Signal To Noise Ratio ◽  
Cosmological Parameters ◽  
Power Spectra ◽  
High Signal ◽  
Mass Energy ◽  
Microwave Background ◽  
Technical Advances ◽  
The Universe

BOOMERanG has recently resolved structures on the last scattering surface at redshift ˜ 1100 with high signal to noise ratio. We review the technical advances which made this possible, and we focus on the current results for maps and power spectra, with special attention to the determination of the total mass-energy density in the Universe and of other cosmological parameters.

scholarly journals Cosmological cross-correlations and nearest neighbour distributions

2021 ◽  
Vol 504 (2) ◽  
pp. 2911-2923
Author(s):  
Arka Banerjee ◽  
Tom Abel
Keyword(s):  
Cross Correlation ◽  
Cosmological Parameters ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Data Sets ◽  
Nearest Neighbour ◽  
Gaussian Density ◽  
Cosmological Data ◽  
Cross Correlations ◽  
Sparse Samples

ABSTRACT Cross-correlations between data sets are used in many different contexts in cosmological analyses. Recently, k-nearest neighbour cumulative distribution functions (kNN-CDF) were shown to be sensitive probes of cosmological (auto) clustering. In this paper, we extend the framework of NN measurements to describe joint distributions of, and correlations between, two data sets. We describe the measurement of joint kNN-CDFs, and show that these measurements are sensitive to all possible connected N-point functions that can be defined in terms of the two data sets. We describe how the cross-correlations can be isolated by combining measurements of the joint kNN-CDFs and those measured from individual data sets. We demonstrate the application of these measurements in the context of Gaussian density fields, as well as for fully non-linear cosmological data sets. Using a Fisher analysis, we show that measurements of the halo-matter cross-correlations, as measured through NN measurements are more sensitive to the underlying cosmological parameters, compared to traditional two-point cross-correlation measurements over the same range of scales. Finally, we demonstrate how the NN cross-correlations can robustly detect cross-correlations between sparse samples – the same regime where the two-point cross-correlation measurements are dominated by noise.

scholarly journals Constraining cosmology with the cosmic microwave and infrared backgrounds correlation

2019 ◽  
Vol 621 ◽  
pp. A32 ◽  
Author(s):  
A. Maniyar ◽  
G. Lagache ◽  
M. Béthermin ◽  
S. Ilić
Keyword(s):  
Large Scale ◽  
Cross Correlation ◽  
Signal To Noise Ratio ◽  
Cosmological Parameters ◽  
Power Spectra ◽  
Matrix Analysis ◽  
Microwave Background ◽  
Residual Level ◽  
Infrared Background ◽  
The Cross

We explore the use of the cosmic infrared background (CIB) as a tracer of the large scale structures for cross-correlating with the cosmic microwave background (CMB) and exploit the integrated Sachs–Wolfe (ISW) effect. We used an improved linear CIB model from our previous work and derived the theoretical CIB×ISW cross-correlation for different Planck HFI frequencies (217, 353, 545 and 857 GHz) and IRAS (3000 GHz). As expected, we predict a positive cross-correlation between the CIB and the CMB whose amplitude decreases rapidly at small scales. We perform a signal-to-noise ratio (S/N) analysis of the predicted cross-correlation. In the ideal case when the cross-correlation is obtained over 70% (40%) of the sky without residual contaminants (e.g. galactic dust) in maps, the S/N ranges from 4.2 to 5.6 (3.2 to 4.3); the highest S/N comes from 857 GHz. A Fisher matrix analysis shows that an ISW signal detected with a S/N this high on the 40% sky can considerably improve the constraints on the cosmological parameters; constraints on the equation of state of the dark energy especially are improved by 80%. We then performed a more realistic analysis considering the effect of residual galactic dust contamination in CIB maps. We calculated the dust power spectra for different frequencies and sky fractions that dominate the CIB power spectra at the lower multipoles we are interested in. Considering a conservative 10% residual level of galactic dust in the CIB power spectra, we observe that the S/N drops drastically, which makes it very challenging to detect the ISW. To determine the capability of current maps to detect the ISW effect through this method, we measured the cross-correlation of the CIB and the CMB Planck maps on the so-called GASS field, which covers an area of ∼11% in the southern hemisphere. We find that with such a small sky fraction and the dust residuals in the CIB maps, we do not detect any ISW signal, and the measured cross-correlation is consistent with zero. To avoid degrading the S/N for the ISW measurement by more than 10% on the 40% sky, we find that the dust needs to be cleaned up to the 0.01% level on the power spectrum.

scholarly journals Constraining galaxy cluster velocity field with the thermal Sunyaev-Zel’dovich and kinematic Sunyaev-Zel’dovich cross-bispectrum

2017 ◽  
Vol 604 ◽  
pp. A93 ◽  
Author(s):  
G. Hurier
Keyword(s):  
Velocity Field ◽  
Galaxy Clusters ◽  
Cross Correlation ◽  
Rest Frame ◽  
Cosmological Parameters ◽  
Galaxy Cluster ◽  
High Signal ◽  
Microwave Background ◽  
Peculiar Motion ◽  
Main Effects

The Sunyaev-Zel’dovich (SZ) effects are produced by the interaction of cosmic microwave background (CMB) photons with the ionized and diffuse gas of electrons inside galaxy clusters integrated along the line of sight. The two main effects are the thermal SZ (tSZ) produced by thermal pressure inside galaxy clusters and the kinematic SZ (kSZ) produced by peculiar motion of galaxy clusters compared to CMB rest-frame. The kSZ effect is particularly challenging to measure as it follows the same spectral behavior as the CMB, and consequently cannot be separated from the CMB using spectral considerations. In this paper, we explore the feasibility of detecting the kSZ through the computation of the tSZ-CMB-CMB cross-correlation bispectrum for current and future CMB experiments. We conclude that the next generation of CMB experiments will offer the possibility to detect the tSZ-kSZ-kSZ bispectrum at high signal-to-noise ration (S/N). This measurement will constraints the intra-cluster dynamics and the velocity field of galaxy cluster that is extremely sensitive to the growth rate of structures and thus to dark energy properties. Additionally, we also demonstrate that the tSZ-kSZ-kSZ bispectrum can be used to break the degeneracies between the mass-observable relation and the cosmological parameters to set tight constraints, up to 4%, on the Y − M relation calibration.

OBSERVABILITY OF THE SZ EFFECT MAP'S NON-GAUSSIAN FEATURES

2006 ◽  
Vol 21 (19) ◽  
pp. 1541-1546 ◽  
Author(s):  
LIANG CAO ◽  
YAO-QUAN CHU
Keyword(s):  
Order Statistics ◽  
Fourth Order ◽  
Cross Correlation ◽  
Hot Gas ◽  
Galaxy Distribution ◽  
Cross Correlations ◽  
Wmap Data ◽  
The Cross ◽  
Non Gaussian ◽  
Cmb Fluctuations

We study the high order cross-correlation between the WMAP map and 2MASS galaxy distribution in order to detect the non-Gaussian behaviors of the SZ effect on the CMB fluctuations induced by 2MASS. The 2MASS distribution is significantly non-Gaussian, which is characterized by the fourth order correlations in DWT representation. With an unbiased mock sample we show, if the CMB data contains the information of 2MASS hot gas caused SZ effect, the non-Gaussianity of the cross-correlations between the CMB and 2MASS is observable with the fourth order statistics on scales of clusters. We compared this result with the cross-correlation between the observed WMAP data and 2MASS, finding similar non-Gaussianity to the mock SZ samples. It strongly evidences the existence and observability of the SZ signal in the WMAP data caused by the 2MASS clusters.

Sign in / Sign up

Export Citation Format

Share Document