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The Cosmic Radio Dipole is of fundamental interest to cosmology. Recent studies revealed open questions about the nature of the observed Cosmic Radio Dipole. We use simulated source count maps to test a linear and a quadratic estimator for…

宇宙学与河外天体物理 · 物理学 2021-12-07 Thilo M. Siewert , Matthias Schmidt-Rubart , Dominik J. Schwarz

The cosmic radio dipole is an anisotropy in the number counts of radio sources, analogous to the dipole seen in the cosmic microwave background (CMB). Measurements of source counts of large radio surveys have shown that though the radio…

宇宙学与河外天体物理 · 物理学 2023-07-05 J. D. Wagenveld , H-R. Klöckner , D. J. Schwarz

We examine the sky distribution of radio galaxies in the NRAO VLA Sky Survey (NVSS) and the Rapid ASKAP Continuum Survey (RACS). Analyses of these samples have reported tension between their inferred dipoles and the kinematic dipole of the…

宇宙学与河外天体物理 · 物理学 2024-06-05 Oliver T. Oayda , Vasudev Mittal , Geraint F. Lewis , Tara Murphy

According to the Cosmological Principle, the matter distribution on very large scales should have a kinematic dipole that is aligned with that of the CMB. We determine the dipole anisotropy in the number counts of two all-sky surveys of…

宇宙学与河外天体物理 · 物理学 2018-04-11 C. A. P. Bengaly , R. Maartens , M. G. Santos

The detection of a dipole anisotropy in the sky distribution of sources in large-scale radio surveys can be used to constrain the magnitude and direction of our local motion with respect to an isotropically distributed extragalactic radio…

天体物理学 · 物理学 2009-11-13 Fronefield Crawford

We use linear estimators to determine the magnitude and direction of the cosmic radio dipole from the NRAO VLA Sky Survey (NVSS) and the Westerbork Northern Sky Survey (WENSS). We show that special attention has to be given to the issues of…

宇宙学与河外天体物理 · 物理学 2013-07-25 Matthias Rubart , Dominik J. Schwarz

We present a realistic modeling of the dipole component of the projected sky distribution of NVSS radio galaxies. The modeling relies on mock catalogs generated within the context of $\Lambda$CDM cosmology, in the linear regime of structure…

宇宙学与河外天体物理 · 物理学 2016-04-07 Prabhakar Tiwari , Adi Nusser

We perform observational tests of statistical isotropy using data from large-scale structure surveys spanning a wide range of wavelengths. Using data from 2MASS, 2MRS, and NVSS galaxies, and BATSE gamma-ray bursts, we constrain the…

宇宙学与河外天体物理 · 物理学 2012-12-10 Cameron Gibelyou , Dragan Huterer

We investigate dipole asymmetries in four large radio surveys, each spanning more than 80\% of the sky. Two of them, the Very Large Array Sky Survey (VLASS) and the Rapid ASKAP Continuum Survey (RACS), have recently yielded dipoles that…

宇宙学与河外天体物理 · 物理学 2024-10-10 Ashok K. Singal

The shape of the curves defined by the counts of radio sources per unit area as a function of their flux density was one of the earliest cosmological probes. Radio source counts continue to be an area of interest, used to study the relative…

宇宙学与河外天体物理 · 物理学 2015-06-15 Ian Heywood , Matt J. Jarvis , James J. Condon

Our motion through the Universe generates a dipole in the temperature anisotropies of the Cosmic Microwave Background (CMB) and also in the angular distribution of sources. If the cosmological principle is valid, these two dipoles are…

宇宙学与河外天体物理 · 物理学 2023-06-09 Charles Dalang , Camille Bonvin

We test the statistical isotropy of the universe by analyzing the distribution of WISE extragalactic sources that were also observed by 2MASS. We pay particular attention to color cuts and foreground marginalization in order to cull a…

宇宙学与河外天体物理 · 物理学 2014-12-04 Mijin Yoon , Dragan Huterer , Cameron Gibelyou , András Kovács , István Szapudi

In recent years, large radio surveys of Active Galactic Nuclei (AGNs), comprising millions of sources, have become available where one could investigate dipole asymmetries, assumedly arising due to a peculiar motion of the Solar system.…

宇宙学与河外天体物理 · 物理学 2023-12-21 Ashok K. Singal

We present the second data release of the MeerKAT Absorption Line Survey (MALS), consisting of wideband continuum catalogues of 391 pointings observed at L~band. The full wideband catalogue covers 4344 deg$^2$ of sky, reaches a depth of 10…

The dipole moment in the angular distribution of the cosmic microwave background (CMB) is thought to originate from the Doppler effect and our motion relative to the CMB frame. Observations of large-scale structure (LSS) should show a…

宇宙学与河外天体物理 · 物理学 2024-03-12 Yun-Ting Cheng , Tzu-Ching Chang , Adam Lidz

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

The angular distribution of the Cosmic Microwave Background Radiation (CMBR) in sky shows a dipole asymmetry, ascribed to the observer's motion (peculiar velocity of the solar system!), relative to the local comoving coordinates. The…

综合物理 · 物理学 2019-09-11 Ashok K. Singal

We present a new approach to constructing and fitting dipoles and higher-order multipoles in synthetic galaxy samples over the sky. Within our Bayesian paradigm, we illustrate that this technique is robust to masked skies, allowing us to…

宇宙学与河外天体物理 · 物理学 2024-12-18 Oliver T. Oayda , Vasudev Mittal , Geraint F. Lewis

The LOFAR Two-metre Sky Survey (LoTSS) will map the complete Northern sky and provide an excellent opportunity to study the distribution and evolution of the large-scale structure of the Universe. We study the completeness of the LoTSS…

The number counts of homogeneous samples of radio sources are a tried and true method of probing the large scale structure of the Universe, as most radio sources outside the galactic plane are at cosmological distances. As such they are…

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