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We undertake a reassessment of one of the large angular scale anomalies observed in cosmic microwave background (CMB) temperature signal referred to as Hemispherical Power Asymmetry (HPA). For the present analysis we use \texttt{SEVEM}…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-17 Sanjeev Sanyal , Sanjeet K. Patel , Pavan K. Aluri , Arman Shafieloo

Precise measurements of the Cosmic Microwave Background (CMB) anisotropy have been one of the foremost concerns in modern cosmology as it provides valuable information on the cosmology of the universe. However, an accurate estimation of the…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-20 Fidy A. Ramamonjisoa , Subharthi Ray , Sanjit Mitra , Tarun Souradeep

We study the Planck CMB temperature at different scales through its derivatives up to second order, which allows one to characterize the local shape and isotropy of the field. The problem of having an incomplete sky in the calculation and…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-22 A. Marcos-Caballero , E. Martínez-González , P. Vielva

We search for planar deviations of statistical isotropy in the Wilkinson Microwave Anisotropy Probe (WMAP) data by applying a recently introduced angular-planar statistics both to full-sky and to masked temperature maps, including in our…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 L. Raul Abramo , Armando Bernui , Thiago S. Pereira

We investigate the presence of primordial oscillatory features in measurements of CMB anisotropies through a systematic comparison of phenomenological templates. Building upon previous searches for primordial features using Planck data, we…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-29 Antonio Raffaelli , Mario Ballardini , Nicola Barbieri

The Cosmological Principle assumes a statistically isotropic Universe, but the Cosmic Microwave Background (CMB) exhibits some anomalous statistical features, such as the hemispherical power asymmetry, that challenge this core assumption.…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-25 Javier Carrón Duque , Mikel Martin Barandiaran , Joseba Martínez-Arrizabalaga

Recent measurements of the temperature field of Cosmic Microwave Background (CMB) provide tantalising evidence for violation of Statistical Isotropy (SI) that constitutes a fundamental tenet of contemporary cosmology. CMB space based…

Cosmology and Nongalactic Astrophysics · Physics 2016-06-08 Suvodip Mukherjee , Tarun Souradeep

We analyze the spectrum of cosmic microwave background (CMB) anisotropies in the timescape cosmology: a potentially viable alternative to homogeneous isotropic cosmologies without dark energy. We exploit the fact that the timescape…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-18 M. Ahsan Nazer , David L. Wiltshire

The standard $\Lambda$CDM model has been highly successful in describing cosmic microwave background (CMB) observations. Nevertheless, a set of large-scale statistical anomalies persists in temperature anisotropies across WMAP and Planck.…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-23 Jiazheng Dou , Wen Zhao

We study statistical anisotropies generated in the observed two-point function of the cosmic microwave background (CMB) fluctuations if the primordial statistics are non-Gaussian. Focusing on the dipole modulations of the anisotropies, we…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-17 Saroj Adhikari , Anne-Sylvie Deutsch , Sarah Shandera

We introduce a new mathematical tool (a direction-dependent probe) to analyse the randomness of purported isotropic Gaussian random fields on the sphere. We apply the probe to assess the full-sky cosmic microwave background (CMB)…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-29 J. Hamann , Q. T. Le Gia , I. H. Sloan , Y. G. Wang , R. S. Womersley

Recently, BICEP2 measurements of the cosmic microwave background (CMB) $B$-mode polarization at degree angular scales has indicated the presence of tensor modes with a high tensor-to-scalar ratio of $r=0.2$ when assuming nearly…

High Energy Physics - Phenomenology · Physics 2015-06-22 Guo-Chin Liu , Kin-Wang Ng , I-Chin Wang

Measurements of the cosmic microwave background (CMB) spectral $y$-distortion anisotropy offer a test for the statistical isotropy of the primordial density perturbations on $0.01\lesssim k{\rm Mpc}\lesssim 1$. We compute the 1-point…

Cosmology and Nongalactic Astrophysics · Physics 2019-01-28 Atsuhisa Ota

Cosmic Microwave Background (CMB) anisotropy encodes a lot of information about our Universe. In this paper we take the ground-based CMB observations (GCMB), including the South Pole Telescope (SPT), SPTpol and the Atacama Cosmology…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-01 Ke Wang , Qing-Guo Huang

Several anomalies appear to be present in the large-angle cosmic microwave background (CMB) anisotropy maps of WMAP, including the alignment of large-scale multipoles. Models in which isotropy is spontaneously broken (e.g., by a scalar…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-13 Haoxuan Zheng , Emory F. Bunn

We investigate the potential of observations of anisotropies in the cosmic microwave background (CMB) and large-scale structure in the Universe to detect possible modifications of standard inflationary models by physics beyond the Planck…

Astrophysics · Physics 2009-11-10 Oystein Elgaroy , Steen Hannestad

We report on the first flight of the balloon-borne QMAP experiment. The experiment is designed to make a map of the cosmic microwave background anisotropy on angular scales from 0.7 to several degrees. Using the map we determine the angular…

We test the tenet of statistical isotropy of the standard cosmological model via a homology analysis of the cosmic microwave background temperature maps. Examining small sectors of the normalized maps, we find that the results exhibit a…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-21 Pratyush Pranav , Thomas Buchert

The Universe's initial conditions, in particular baryon and cold dark matter (CDM) isocurvature perturbations, are poorly constrained on sub-Mpc scales. In this paper, we develop a new formalism to compute the effect of small-scale baryon…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-24 Nanoom Lee , Yacine Ali-Haïmoud

We study Planck 2015 cosmic microwave background (CMB) anisotropy data using the energy density inhomogeneity power spectrum generated by quantum fluctuations during an early epoch of inflation in the non-flat $\Lambda$CDM model. Unlike…

Cosmology and Nongalactic Astrophysics · Physics 2018-09-19 Junpei Ooba , Bharat Ratra , Naoshi Sugiyama
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