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In an anisotropic universe, observers not positioned at a point of special symmetry should observe cosmic parallax - the relative angular motion of test galaxies over cosmic time. It was recently argued that the non-observance of this…

宇宙学与河外天体物理 · 物理学 2009-12-30 Michele Fontanini , Mark Trodden , Eric J. West

Refined astrometry measurements allow us to detect large-scale deviations from isotropy through real-time observations of changes in the angular separation between sources at cosmic distances. This "cosmic parallax" effect is a powerful…

天体物理学 · 物理学 2009-06-16 Claudia Quercellini , Miguel Quartin , Luca Amendola

Cosmic parallax is the change of angular separation between pair of sources at cosmological distances induced by an anisotropic expansion. An accurate astrometric experiment like Gaia could observe or put constraints on cosmic parallax.…

宇宙学与河外天体物理 · 物理学 2009-11-06 Claudia Quercellini , Paolo Cabella , Luca Amendola , Miguel Quartin , Amedeo Balbi

Recent released Planck data and other astronomical observations show that the universe may be anisotropic on large scales. Inspired by this, anisotropic cosmological models have been proposed. We note that the Finsler-Randers spacetime…

宇宙学与河外天体物理 · 物理学 2014-03-25 Zhe Chang , Xin Li , Hai-Nan Lin , Sai Wang

In recent years the possibility of measuring the temporal change of radial and transverse position of sources in the sky in real time have become conceivable thanks to the thoroughly improved technique applied to new astrometric and…

宇宙学与河外天体物理 · 物理学 2012-11-26 Claudia Quercellini , Luca Amendola , Amedeo Balbi , Paolo Cabella , Miguel Quartin

Cosmological galaxy formation simulations are powerful tools to understand the complex processes that govern the formation and evolution of galaxies. However, evaluating the realism of these simulations remains a challenge. The two common…

If the Universe is endowed with cosmic anisotropy, it will have a preferred direction of expansion. Reconstructing the expansion history by Gaussian Process (GP) can be used to probe the cosmic anisotropy model-independently. In this paper,…

宇宙学与河外天体物理 · 物理学 2025-02-25 Zong-Fan Yang , Da-Wei Yao , Ke Wang

The cosmological principle is a cornerstone of the standard cosmological model. However, recent observations suggest potential deviations from this assumption, hinting at a small anisotropic expansion. Such an expansion can arise from…

Absolute distances from strong lensing can anchor Type Ia Supernovae (SNe Ia) at cosmological distances giving a model-independent inference of the Hubble constant ($H_0$). Future observations could provide strong lensing time-delay…

宇宙学与河外天体物理 · 物理学 2024-01-29 Xiaolei Li , Ryan E. Keeley , Arman Shafieloo , Kai Liao

Distant objects in the solar system are crucial to better understand the history and evolution of its outskirts. The stellar occultation technique allows the determination of their sizes and shapes with kilometric accuracy, a detailed…

The cosmological principle asserts that the Universe is homogeneous and isotropic on large enough scales. However, alternative cosmological models can bring about anisotropies through local inhomogeneities, anisotropic evolution, or exotic…

The methodical properties of the original difference method for the search of the anisotropy at the knee region of the primary cosmic radiation energy spectrum are analyzed. The main feature of the suggested method is a study of the…

天体物理仪器与方法 · 物理学 2015-10-01 V. P. Pavlyuchenko , R. M. Martirosov , N. M. Nikolskaya , A. D. Erlykin

The light we observe from distant astrophysical objects including supernovae and quasars allows us to determine large distances in terms of a cosmological model. Despite the success of the standard cosmological model in fitting the data,…

宇宙学与河外天体物理 · 物理学 2024-05-07 Angela L. H. Ng

Studies of weak gravitational lensing by large-scale structures require the measurement of the distortions introduced to the shapes of distant galaxies at the few percent level by anisotropic light deflection along the line of sight. To…

天体物理学 · 物理学 2009-11-07 Andrew W. Blain

The Cosmological Principle posits that the Universe is isotropic on the largest scales. While widely supported, this foundational assumption remains testable. We analyse the angular distribution of over one million quasars from the…

宇宙学与河外天体物理 · 物理学 2025-07-04 Amit Mondal , Biswajit Pandey , Krishna Ghosh

In this work we present the first results from a new ray-tracing tool to calculate cosmological distances in the context of fully nonlinear general relativity. We use this tool to study the ability of the general cosmographic representation…

宇宙学与河外天体物理 · 物理学 2023-03-15 Hayley J. Macpherson

We present a comparative analysis of estimators and Bayesian methods for determining the number count dipole from cosmological surveys. The increase in discordance between the number count dipole and the CMB's kinematic dipole has presented…

宇宙学与河外天体物理 · 物理学 2025-09-30 Vasudev Mittal , Oliver T. Oayda , Geraint F. Lewis

We apply four different mass modelling methods to a suite of publicly available mock data for spherical stellar systems. We focus on the recovery of the density and velocity anisotropy as a function of radius, using either line-of-sight…

星系天体物理 · 物理学 2020-12-02 J. I. Read , G. A. Mamon , E. Vasiliev , L. L. Watkins , M. G. Walker , J. Penarrubia , M. Wilkinson , W. Dehnen , P. Das

We investigate the observational effects of a quintessence model in an anisotropic spacetime. The anisotropic metric is a non-rotating particular case of a generalized Godel's metric and is classified as Bianchi III. This metric is an exact…

宇宙学与河外天体物理 · 物理学 2014-07-23 W. Miranda , S. Carneiro , C. Pigozzo

The standard cosmology strongly relies upon the Cosmological Principle, which consists on the hypotheses of large scale isotropy and homogeneity of the Universe. Testing these assumptions is, therefore, crucial to determining if there are…

宇宙学与河外天体物理 · 物理学 2018-04-27 U. Andrade , C. A. P. Bengaly , J. S. Alcaniz , B. Santos
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