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A cosmic ray observatory with full-sky coverage can exploit standard anisotropy analysis methods that do not work if part of the celestial sphere is never seen. In particular, the distribution of arrival directions can be fully…

Astrophysics · Physics 2009-10-31 Paul Sommers

Anisotropies in the Cosmic Microwave Background (CMB) contain a wealth of information about the past history of the universe and the present values of cosmological parameters. I ouline some of the theoretical advances of the last few years.…

Astrophysics · Physics 2007-05-23 Scott Dodelson

Cosmic microwave background (CMB) anisotropies probe the primordial density field at the edge of the observable Universe. There is a limiting precision (``cosmic variance'') with which anisotropies can determine the amplitude of primordial…

Astrophysics · Physics 2016-08-25 Marc Kamionkowski , Abraham Loeb

Cosmic microwave background (CMB) temperature anisotropies have and will continue to revolutionize our understanding of cosmology. The recent discovery of the previously predicted acoustic peaks in the power spectrum has established a…

Astrophysics · Physics 2011-07-19 Wayne Hu , Scott Dodelson

Cosmic strings, a hot subject in the 1980's and early 1990's, lost its appeal when it was found that it leads to inconsistencies in the power spectrum of the measured cosmic microwave background temperature anisotropies. However,…

High Energy Physics - Theory · Physics 2008-11-26 Mairi Sakellariadou

Important informations on the origin and the propagation mechanisms of cosmic rays may be provided by the measurement of the anisotropies of their arrival direction. In this paper the observation of anisotropy regions at different angular…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Roberto Iuppa

Whilst standard field theoretic Cosmic Strings cannot end, Cosmic Superstrings can form three string junctions, at which each string ends. This opens up a new class of possible boundary conditions for such strings and we show that, at least…

General Relativity and Quantum Cosmology · Physics 2014-11-20 William Nelson

Mild, unavoidable deviations from circular-symmetry of instrumental beams along with scan strategy can give rise to measurable Statistical Isotropy (SI) violation in Cosmic Microwave Background (CMB) experiments. If not accounted properly,…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-06 Nidhi Pant , Santanu Das , Aditya Rotti , Sanjit Mitra , Tarun Souradeep

Cosmic string wakes produce direct B-mode polarization at leading order in cosmological perturbation theory, as worked out in a previous publication \cite{BDH} in the case of a single string wake. Here we compute the angular power spectrum…

Cosmology and Nongalactic Astrophysics · Physics 2013-08-28 Robert Brandenberger , Nick Park , Grant Salton

The breakdown of statistical homogeneity and isotropy of cosmic perturbations is a generic feature of ultra large scale structure of the cosmos, in particular, of non trivial cosmic topology. The statistical isotropy (SI) of the Cosmic…

Astrophysics · Physics 2008-11-26 Tarun Souradeep , Amir Hajian

We present a significant update of the constraints on the Abelian Higgs cosmic string tension by cosmic microwave background (CMB) data, enabled both by the use of new high-resolution CMB data from suborbital experiments as well as the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 J. Urrestilla , N. Bevis , M. Hindmarsh , M. Kunz

Gravitational lensing distorts the cosmic microwave background (CMB) anisotropies and imprints a characteristic pattern onto it. The distortions depend on the projected matter density between today and redshift $z \sim 1100$. In this paper…

Astrophysics · Physics 2016-08-25 Matias Zaldarriaga , Uros Seljak

We present a simple, yet accurate approximation for calculating the cosmic microwave background anisotropy power spectrum in adiabatic models. It consists of solving for the evolution of a two-fluid model until the epoch of recombination…

Astrophysics · Physics 2009-10-22 Uros Seljak

Cosmic microwave background (CMB) anisotropy may result from both scalar and tensor perturbations. For a sufficiently narrow range of angular scales, CMB perturbations can be characterized by four parameters. Results from the Cosmic…

Astrophysics · Physics 2009-10-22 Scott Dodelson , Lloyd Knox , Edward W. Kolb

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

We investigate cosmological evolution and implications of cosmic strings with time-dependent tension. We derive basic equations of time development of the correlation length and the velocity of such strings, based on the one scale model.…

High Energy Physics - Phenomenology · Physics 2008-11-26 Kazuhide Ichikawa , Tomo Takahashi , Masahide Yamaguchi

Cosmic microwave background (CMB) anisotropies and density fluctuations are calculated for flat cold dark matter (CDM) models with a wide range of parameters, i.e., $\Omega_0, h$ and $\Omega_B$ for both standard recombination and various…

Astrophysics · Physics 2009-10-22 Naoshi Sugiyama

In models with a cosmological constant, a significant component of the large scale cosmic microwave background (CMB) anisotropy is produced at rather low redshifts, z < 1. In these models, the gravitational potential perturbations begin to…

Astrophysics · Physics 2009-07-09 Robert G. Crittenden , Neil Turok

The existence of cosmic superstrings may be probed by astronomical time domain surveys. When crossing the line of sight to point-like sources, strings produce a distinctive microlensing signature. We consider two avenues to hunt for a relic…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-14 David F. Chernoff , Ariel Goobar , Janina J. Renk

We show that time dependent gravitational potential can be directly detected from the cosmic microwave background (CMB) anisotropies. The signature can be measured by cross-correlating the CMB with the projected density field reconstructed…

Astrophysics · Physics 2009-10-31 Uros Seljak , Matias Zaldarriaga