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In the last decade, a number of experiments dealt with the problem of measuring the arrival direction distribution of cosmic rays, looking for information on the propagation mechanisms and the identification of their sources. Any deviation…

Instrumentation and Methods for Astrophysics · Physics 2015-06-12 Roberto Iuppa , Giuseppe Di Sciascio

The Gaia mission is expected to provide highly accurate astrometric, photometric, and spectroscopic measurements for about $10^9$ objects. Automated classification of detected sources is a key part of the data processing. Here a few aspects…

Astrophysics · Physics 2008-12-02 A. Vallenari , R. Sordo

Measuring time delays between the multiple images of gravitationally lensed quasars is now recognized as a competitive way to constrain the cosmological parameters, and it is complementary with other cosmological probes. This requires long…

Cosmology and Nongalactic Astrophysics · Physics 2013-06-21 M. Tewes , F. Courbin , G. Meylan

We present a novel, purely geometric probe of cosmology based on measurements of differential time delays between images of strongly lensed quasars due to finite source effects. Our approach is solely dependent on cosmology via a ratio of…

Cosmology and Nongalactic Astrophysics · Physics 2019-12-16 Angela L. H. Ng , Geraint F. Lewis

The measurement of large scale anisotropies in cosmic ray arrival directions is generally performed through harmonic analyses of the right ascension distribution as a function of energy. These measurements are challenging due to the small…

Instrumentation and Methods for Astrophysics · Physics 2013-07-29 Olivier Deligny , Francesco Salamida

We develop a method based on the angular distribution on the sky of cosmological parameters to probe the inhomogeneity of large-scale structure and cosmic acceleration. We demonstrate this method on the largest type Ia supernova (SN) data…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-10 C. Sofia Carvalho , Katrine Marques

Over the course of several years, stars trace helical trajectories as they traverse across the sky due to the combined effects of proper motion and parallax. It is well known that the gravitational pull of an unseen companion can cause…

Solar and Stellar Astrophysics · Physics 2023-07-05 Jeff J. Andrews , Katelyn Breivik , Chirag Chawla , Carl Rodriguez , Sourav Chatterjee

We present a novel approach to disentangle two key contributions to the largest-scale anisotropy of the galaxy distribution: (i) the intrinsic dipole due to clustering and anisotropic geometry, and (ii) the kinematic dipole due to our…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-09 Tobias Nadolny , Ruth Durrer , Martin Kunz , Hamsa Padmanabhan

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 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 cosmological principle, as the cornerstone of the standard cosmological model, requires that the Universe be homogeneous and isotropic on large scales. As a fundamental assumption, it is constantly subjected to testing via various…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-21 Jianping Hu , Chao Geng , Xuandong Jia , Zhaoyu Zuo , Taozhi Yang , Fayin Wang

Usually, we assume that there is no inhomogeneity isotropic in terms of our location in our uni- verse. This assumption has not been observationally confirmed yet in sufficient accuracy, and we need to consider the possibility that there…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-06 Hiroyuki Negishi , Ken-ichi Nakao

We use detailed numerical simulations and the $\upsilon$ Andromedae, planetary system as a template to evaluate the capability of the ESA Cornerstone Mission GAIA in detecting and measuring multiple planets around solar-type stars in the…

Astrophysics · Physics 2009-11-06 A. Sozzetti , S. Casertano , M. G. Lattanzi , A. Spagna

The measurement of large scale anisotropies in cosmic ray arrival directions at energies above 10^13 eV is performed through the detection of Extensive Air Showers produced by cosmic ray interactions in the atmosphere. The observed…

Instrumentation and Methods for Astrophysics · Physics 2011-08-31 R. Bonino , V. V. Alekseenko , O. Deligny , P. L. Ghia , M. Grigat , A. Letessier-Selvon , H. Lyberis , S. Mollerach , S. Over , E. Roulet

Inhomogeneous universe models have been proposed as an alternative explanation for the apparent acceleration of the cosmic expansion that does not require dark energy. In the simplest class of inhomogeneous models, we live within a large,…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Michael Blomqvist , Edvard Mortsell

The Cosmological Principle is a cornerstone of the standard model of cosmology and shapes how we view the Universe and our place within it. It is imperative, then, to devise multiple observational tests which can identify and quantify…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-13 James Adam , Roy Maartens , Julien Larena , Chris Clarkson

Investigating intrinsic alignments (IAs) of galaxy shapes is important not only to constrain cosmological parameters unbiasedly from gravitational lensing but also to extract cosmological information complimentary to galaxy clustering…

Cosmology and Nongalactic Astrophysics · Physics 2020-02-26 Teppei Okumura , Atsushi Taruya

A time-distance measurement technique is derived to isolate phase travel time anisotropy caused by subsurface horizontal magnetic fields, and a method which uses the measured anisotropy to estimate the field's orientation is also derived. A…

Solar and Stellar Astrophysics · Physics 2022-05-11 John T. Stefan , Alexander G. Kosovichev

High-precision astrometry well beyond the capacities of Gaia will provide a unique way to achieve astrophysical breakthroughs, in particular on the nature of dark matter, and a complete survey of nearby habitable exoplanets. In this…

Major advancements in space science and detector technology brought about a revolution in global astrometry, the science of measuring distances and motions of stars in the Milky Way and in the local universe. From the first ESA astrometric…

Instrumentation and Methods for Astrophysics · Physics 2025-04-01 Beatrice Bucciarelli