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The periodic solution of the Friedmann equation in conformal time, implies that only cosmological perturbations exhibiting corresponding symmetries are physically permissible, leading to a discrete spectrum of allowed wave vectors.…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-15 Wei-Ning Deng , Will Handley

We present a pedagogical and phenomenological introduction to the study of cosmic microwave background (CMB) polarization to build intuition about the prospects and challenges facing its detection. Thomson scattering of temperature…

Astrophysics · Physics 2009-08-18 Wayne Hu , Martin White

The standard inflationary model presents a simple scenario within which the homogeneity, isotropy and flatness of the universe appear as natural outcomes and, in addition, fluctuations in the energy density are originated during the…

Astrophysics · Physics 2023-03-08 E. Martinez-Gonzalez , P. Vielva

We study the spectral theory and inverse problem on asymptotically hyperbolic manifolds. The main subjects are as follows: (1)Location of the essential spectrum. (2)Absence of eigenvalues embedded in the continuous spectrum. (3)Limiting…

Spectral Theory · Mathematics 2012-08-23 Hiroshi Isozaki , Yaroslav Kurylev

Detailed knowledge of the primordial power spectrum of curvature perturbations is essential both in order to elucidate the physical mechanism (`inflation') which generated it, and for estimating the cosmological parameters from observations…

Cosmology and Nongalactic Astrophysics · Physics 2014-01-17 Paul Hunt , Subir Sarkar

Cross-correlations between Cosmic Microwave Background (CMB) temperature and $y$-spectral distortions anisotropies have been previously proposed as a way to measure the local bispectrum parameter $f_{\rm NL}^{\rm loc.}$ in a range of scales…

Cosmology and Nongalactic Astrophysics · Physics 2017-10-04 Andrea Ravenni , Michele Liguori , Nicola Bartolo , Maresuke Shiraishi

We consider an inverse source problem for the Helmholtz equation in a bounded domain. The problem is to reconstruct the shape of the support of a source term from the Cauchy data on the boundary of the solution of the governing equation. We…

Analysis of PDEs · Mathematics 2017-05-09 Masaru Ikehata

We investigate a relativistic cosmological model with background rotation, sourced by a non-perfect fluid with anisotropic stress. A modified version of the CLASS Boltzmann code is employed to perform Monte Carlo Markov Chain analyses…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-16 Micol Benetti , David A. Cook , Saulo Carneiro

Recent Wilkinson Microwave Anisotropy Probe (WMAP) data confirm the Cosmic Microwave Background (CMB) quadrupole anomaly. We further elaborate our previous proposal that the quadrupole power can be naturally suppressed in axis-symmetric…

Astrophysics · Physics 2008-11-26 L. Campanelli , P. Cea , L. Tedesco

The initial-value problem for cylindrical gravitational waves is studied through the development of the inverse scattering method scheme. The inverse scattering transform in this case can be viewed as a transformation of the Cauchy data to…

General Relativity and Quantum Cosmology · Physics 2007-05-23 G. G. Varzugin

We study the cosmic microwave background (CMB) anisotropy due to spherically symmetric nonlinear structures in flat universes with dust and a cosmological constant. By modeling a time-evolving spherical compensated void/lump by…

Astrophysics · Physics 2009-02-20 Nobuyuki Sakai , Kaiki Taro Inoue

We present ABCMB, a differentiable Einstein-Boltzmann solver for the cosmic microwave background (CMB). ABCMB is a complete code capturing important effects to linear order in $\Lambda{\rm CDM}$ cosmology. It computes the CMB power spectrum…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-18 Zilu Zhou , Cara Giovanetti , Hongwan Liu

We combine detections of anisotropy in the Cosmic Microwave Background radiation with observations of inhomogeneity in the large-scale distribution of galaxies to test the predictions of models of cosmological structure formation. This…

Astrophysics · Physics 2009-09-25 Eric Gawiser

We propose a machine learning approach to the blind detection of extragalactic point sources on maps of the temperature anisotropies of the cosmic microwave background. Using realistic simulations of the microwave sky as seen by Planck, we…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-01 P. Diego-Palazuelos , R. B. Barreiro , P. Vielva , D. Balbás , M. López-Caniego , D. Herranz , B. Casaponsa

The Cosmic Microwave Background Radiation (CMB) is an invaluable probe of the conditions of the early universe. Recent measurements of its spatial anisotropy have allowed accurate determinations of several fundamental cosmological…

Astrophysics · Physics 2009-09-29 Christopher O'Dell

This paper addresses the challenging and interesting inverse problem of reconstructing the spatially varying dielectric constant of a medium from phaseless backscattering measurements generated by single-point illumination. The underlying…

Numerical Analysis · Mathematics 2025-06-30 Thuy T. Le , Phuong M. Nguyen , Loc H. Nguyen

Current estimates of number counts of radio sources in the frequency range where the most sensitive Cosmic Microwave Background (CMB) experiments are carried out significantly under-represent sources with strongly inverted spectra. Hot…

Astrophysics · Physics 2009-10-31 Rosalba Perna , Tiziana Di Matteo

There have been vigorous research attempts to test various modified gravity theories by usingphysics of the cosmic microwave background (CMB). Meanwhile, symmetry breaking such as Higgsmechanism is one of the most important phenomena in…

General Relativity and Quantum Cosmology · Physics 2020-07-01 Jiwon Park , Tae Hoon Lee

This paper is concerned with an inverse moving point source problem in electromagnetics. The aim is to reconstruct the moving orbit from the tangential components of magnetic fields taken at a finite number of observation points. The…

Numerical Analysis · Mathematics 2025-07-22 Minghui Li , Guanghui Hu , Yue Zhao

In standard cosmology, Cosmic Microwave Background photons near the last scattering surface exhibit only linear polarization due to Compton scattering, leading to the assumption that primordial circular polarization is negligible. However,…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-07 Iman Motie , Jafar Khodagholizadeh , S. Mahmoudi , Brahim Lamine , Alain Blanchard