English
Related papers

Related papers: Estimates of multipolar coefficients to search for…

200 papers

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

This PhD thesis (defended in 2014) is focused on the estimation of the CMB polarised anisotropies power spectra on a masked sky and on forecasts of constraints set on the primordial universe physics thanks to these anisotropies. After an…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 A. Ferte

Likelihood fitting to two-point clustering statistics made from galaxy surveys usually assumes a multivariate normal distribution for the measurements, with justification based on the central limit theorem given the large number of…

Cosmology and Nongalactic Astrophysics · Physics 2019-04-23 Mike Shengbo Wang , Will J. Percival , Santiago Avila , Robert Crittenden , Davide Bianchi

This study presents preliminary results from the analysis of cosmic-ray anisotropy using air showers detected by the IceTop surface array between 2011 and 2022. With improved statistical precision and updated Monte Carlo simulation events…

High Energy Astrophysical Phenomena · Physics 2025-08-01 Rasha Abbasi , Paolo Desiati , Juan Carlos Díaz Vélez , Frank McNally

The distribution of arrival directions of ultra-high energy cosmic rays may yield clues to their mysterious origin. We introduce a method of {\it invariant statistics} to analyze cosmic ray data which eliminates coordinate-dependent…

Astrophysics · Physics 2009-11-07 Soebur Razzaque , John P. Ralston

X-ray polarimetry has the potential to make key-contributions to our understanding of galactic compact objects like binary black hole systems and neutron stars, and extragalactic objects like active galactic nuclei, blazars, and Gamma Ray…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 Henric Krawczynski

We present a Monte Carlo simulation for the scattering of light in the case of an isotropic light source. The scattering phase functions are studied particularly in detail to understand how they can affect the multiple light scattering in…

Instrumentation and Methods for Astrophysics · Physics 2014-02-18 J. Colombi , K. Louedec

Power spectrum estimation and evaluation of associated errors in the presence of incomplete sky coverage; non-homogeneous, correlated instrumental noise; and foreground emission is a problem of central importance for the extraction of…

Astrophysics · Physics 2016-08-30 J. Jewell , S. Levin , C. H. Anderson

Measurements of the polarization angle and orientation of cosmological radio sources may be used to search for unusual effects in the propagation of light through the universe. Recently, Nodland and Ralston (astro-ph/9704196) have claimed…

Astrophysics · Physics 2009-10-30 Sean M. Carroll , George B. Field

The disagreement between low- and high-redshift measurements of the Hubble parameter is emerging as a serious challenge to the standard model of cosmology. We develop a covariant cosmographic analysis of the Hubble parameter in a general…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-13 Roy Maartens , Jessica Santiago , Chris Clarkson , Basheer Kalbouneh , Christian Marinoni

Ground-based full-sky studies of the angular distribution of arrival directions of ultra-high-energy cosmic rays require combining data from different observatories, such as the Pierre Auger Observatory (Auger) and the Telescope Array (TA),…

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

The peculiar motion of the Earth causes a dipole anisotropy modulation in the distant galaxy distribution due to the aberration effect. However, the amplitude and angular direction of the effect is not necessarily the same as those of the…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-12 Yousuke Itoh , Kazuhiro Yahata , Masahiro Takada

A recent study of the rotation of the plane of polarization of light from 160 cosmological sources claims to find significant evidence for cosmological anisotropy. We point out methodological weaknesses of that study, and reanalyze the same…

Astrophysics · Physics 2009-12-30 Thomas J. Loredo , Eanna E. Flanagan , Ira M. Wasserman

Any isotropy violating phenomena on cosmic microwave background (CMB) induces off-diagonal correlations in the two-point function. These correlations themselves can be used to estimate the underlying anisotropic signals. Masking due to…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-09 Pavan K. Aluri , Nidhi Pant , Aditya Rotti , Tarun Souradeep

We show how to achieve the notion of "multicalibration" from H\'ebert-Johnson et al. [2018] not just for means, but also for variances and other higher moments. Informally, it means that we can find regression functions which, given a data…

Machine Learning · Computer Science 2020-08-19 Christopher Jung , Changhwa Lee , Mallesh M. Pai , Aaron Roth , Rakesh Vohra

Anisotropies in the distance-redshift relation of cosmological sources are expected due to large-scale inhomogeneities in the local Universe. When the observed sources are tracing a large-scale matter flow in a general spacetime geometry,…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-05 Julian Adamek , Chris Clarkson , Ruth Durrer , Asta Heinesen , Martin Kunz , Hayley J. Macpherson

The measurement of the anisotropies of cosmic ray arrival direction provides important informations on the propagation mechanisms and on the identification of their sources. In this paper we report the observation of anisotropy regions at…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Giuseppe Di Sciascio , Roberto Iuppa

Studies show that the model-independent, fully non-perturbative covariant cosmographic approach is suitable for analyzing the local Universe $(z\lesssim 0.1)$. However, accurately characterizing large and inhomogeneous mass distributions…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-05 Basheer Kalbouneh , Jessica Santiago , Christian Marinoni , Roy Maartens , Chris Clarkson , Maharshi Sarma

In the standard diffusive picture for transport of cosmic rays (CRs), a gradient in the CR density induces a typically small, dipolar anisotropy in their arrival directions. This has been widely advertised as a tool for finding nearby…

High Energy Astrophysical Phenomena · Physics 2015-01-15 Philipp Mertsch , Stefan Funk
‹ Prev 1 3 4 5 6 7 10 Next ›