arXiv subjects

A. O. Mihalchenko

Publications and source records attributed to A. O. Mihalchenko.

5 recordsLinked to original sources

arXiv2026

Prospects for an independent measurement of $\boldsymbol{\ell}$=1,2,3 CMB anisotropy multipoles using the anisotropic Sunyaev-Zel'dovich effect

We investigate the prospects for observing a specific spectral distortion of the cosmic microwave background, which occurs due to the anisotropy of the radiation when it is scattered by hot plasma of galaxy clusters. Detection of this anisotropic Sunyaev-Zel'dovich effect would enable an independent measurement of the CMB anisotropy multipoles with $\ell = 1, 2, 3$, allow the Sachs-Wolfe and integrated Sachs-Wolfe (Rees-Sciama) effects to be separated, and partially solve the cosmic variance problem for low multipoles. We applied the Least Response Method for component separation in the data processing and estimated the required sensitivity of the experiment for such observations. We test our approach on a simulated signal that is contaminated by various foregrounds with poorly defined spectral shapes, along with distortions of the relic blackbody spectrum caused by the Sunyaev-Zel'dovich effect and its relativistic corrections.

astro-ph.CO↗

arXiv2025

Probing CMB Polarization Gaussianity with the Statistics of Unpolarized Points: Non-Gaussianity of Planck Data and Prospects for Future B-Mode Measurements

We present a Gaussianity test of the cosmic microwave background (CMB) polarization by analyzing the statistics of unpolarized points in the sky, classified into three distinct types: saddles, comets, and beaks. This classification of singular points where both Stokes parameters $Q$ and $U$ vanish stems from the fact that linear polarization is described by a second-rank tensor. By varying the number of spherical harmonics included in the polarization maps, one can probe the statistics of these singularities across a range of angular scales. Applying this method to Planck data we find clear evidence of non-Gaussianity in both $E$ and $B$ modes of polarization. This approach may be especially useful for processing data from current and future experiments such as the Simons Observatory (SO). In particular, it can help to assess the Gaussianity of a potentially detected B mode signal, thereby determining whether it arises from primordial tensor perturbations -- as predicted by inflation -- or from alternative sources such as polarized foregrounds (e.g., thermal dust), E-to-B mode leakage, systematics, photon noise or gravitational lensing. We have made publicly available software that finds unpolarized points of all three types on any polarization map in Hierarchical Equal Area isoLatitude Pixelation (HEALPix) format with full or incomplete sky coverage to enable testing of the observed signal for Gaussianity.

astro-ph.CO↗

arXiv2025

Disentangling CMB $μ$ and $y$ spectral distortions from foregrounds with poorly defined spectral shapes

We have presented a new approach to separate small spectral $μ$ and $y$ distortions of the CMB from foreground components with poorly defined spectral shapes. Our linear method, called the Least Response Method (LRM), is based on the idea of simultaneously minimizing the response to all possible foregrounds and photon noise while maintaining a constant response to the useful signal. We compared our approach with the mILC method, which is a modification of the Internal Linear Combination previously used for CMB anisotropy maps, and proved the advantages of LRM. In addition, we found the optimal temperature of the telescope optical system for any experiments related to the study of the CMB $μ$ distortions.

astro-ph.CO↗

arXiv2023

Separation of CMB $μ$ spectral distortions from foregrounds with poorly defined spectral shapes

This paper proposes a new approach to separate the $μ$ spectral distortions of the cosmic microwave background from foregrounds with poorly defined spectral shapes. The idea is based on finding the optimal response to the observed signal. This response is weakly sensitive to foregrounds with parameters that are within some certain limits of their possible variations and, at the same time, very sensitive to the amplitude of $μ$ distortion. The algorithm described in this paper is stable, easy to implement, and simultaneously minimizes the response to foregrounds and photon noise.

astro-ph.CO↗

arXiv2020

Stokes parameters spectral distortions due to the Sunyaev-Zel'dovich effect and an independent estimation of the CMB low multipoles

We consider the Stokes parameters' frequency spectral distortions arising due to Compton scattering of the anisotropic cosmic microwave background (CMB) radiation, the Sunyaev-Zel' dovich effect (SZ), towards clusters of galaxies. We single out a very special type of such distortions and find simple analytical formulas for them. We show that this kind of distortion has a very distinctive spectral shape and can be separated from other kinds of contaminants. We demonstrate that this effect gives us an opportunity for an independent estimation of the low-multipole angular CMB anisotropies, such as the dipole, the quadrupole, and the octupole. We also show that, using distorted signals from nearby and distant clusters, one can distinguish between the Sachs-Wolfe and the integrated Sachs-Wolfe effects. The detection of such distortions can be feasible with high-angular resolution and high-sensitivity space missions, such as the upcoming Millimetron Space Observatory experiment.

astro-ph.CO↗