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We study the dipole signal in the spectral index (x) of the differential number counts using quasars in the CatWISE2020 catalog of infrared sources. The index is extracted by using the log-likelihood method. We obtain the value $x=1.579 \pm…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-29 Mohit Panwar , Pankaj Jain

To date, the most precise measurement of the observer's peculiar velocity comes from the dipole in the Cosmic Microwave Background (CMB). This velocity also generates a dipole in the source number counts, whose amplitude is governed not…

Cosmology and Nongalactic Astrophysics · Physics 2024-08-27 Fabien Lacasa , Camille Bonvin , Charles Dalang , Ruth Durrer

We study the dipole anisotropy in number counts and flux density weighted number counts {or sky brightness} in the NRAO VLA Sky Survey (NVSS) data. The dipole anisotropy is expected due to our local motion with respect to the CMBR rest…

Cosmology and Nongalactic Astrophysics · Physics 2014-07-29 Prabhakar Tiwari , Rahul Kothari , Abhishek Naskar , Sharvari Nadkarni-Ghosh , Pankaj Jain

We determine the dipole in the WISE galaxy catalogue. After reducing star contamination to <0.1% by rejecting sources with high apparent motion and those close to the Galactic plane, we eliminate low redshift sources to suppress the…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-30 M. Rameez , R. Mohayaee , S. Sarkar , J. Colin

The signal of dipole anisotropy in quasar number counts is studied using the CatWISE2020 catalog in various color bins. It is found that the dipole signal differs significantly in two color bins, namely, $1.1>W1-W2\ge 0.8$ and…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-28 Mohit Panwar , Pankaj Jain , Amitesh Omar

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…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-09 Charles Dalang , Camille Bonvin

We use numerical simulations to investigate the behaviour of the dipole moment of the spatial distribution of different kinds of mass tracers. We select density peaks of the simulated matter distribution with mean separations of 38 and 30…

Astrophysics · Physics 2015-06-24 V. Kolokotronis , M. Plionis , P. Coles , S. Borgani , L. Moscardini

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

The cosmological principle posits that the universe is statistically homogeneous and isotropic on large scales, implying all matter shares the same rest frame. This principle suggests that velocity estimates of our motion from various…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-02 Pedro da Silveira Ferreira , Valerio Marra

The cosmic dipole anomaly, currently detected at a significance exceeding 5$\sigma$ in several independent survey poses a significant challenge to the standard model of cosmology. The Ellis & Baldwin formula provides a theoretical link…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-29 Albert Bonnefous

We apply Simulation-Based Inference ('SBI') to the cosmic dipole problem for the first time, measuring the distribution of quasar counts over the sky in the CatWISE2020 ('CatWISE') sample. We show that the quadrupole anisotropy in CatWISE…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-06 Oliver T. Oayda , Geraint F. Lewis

Starting from the observed distribution of galaxy clusters in redshift space we use a two--step procedure to recover their distances and peculiar velocities. After statistically correcting for the unobserved cluster distribution in the zone…

Astrophysics · Physics 2016-08-30 E. Branchini , M. Plionis

The velocity of the Sun with respect to the cosmic microwave background (CMB) can be extracted from the CMB dipole, provided its intrinsic dipole is assumed to be small in comparison. This interpretation is consistent, within fairly large…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-24 Charles Dalang , Ruth Durrer , Fabien Lacasa

An observer moving with respect to the cosmic rest frame should observe a concentration and brightening of galaxies in the direction of motion and a spreading and dimming in the opposite direction. The velocity inferred from this dipole…

Cosmology and Nongalactic Astrophysics · Physics 2022-06-08 Jeremy Darling

The standard method of measuring the galaxy pairwise velocity dispersion on small scales is heavily weighted by the densest regions in a way that is difficult to calibrate. We propose a new statistic which measures the small-scale velocity…

Astrophysics · Physics 2009-10-30 Michael A. Strauss , Jeremiah P. Ostriker , Renyue Cen

This work is a follow-up to the paper, "Numerical Relativity as a Tool for Studying the Early Universe". In this article, we determine if cosmological gravitational waves can be accurately extracted from a dynamical spacetime using an…

General Relativity and Quantum Cosmology · Physics 2017-04-24 David Garrison , Christopher Ramirez

We present a new method for recovering the underlying velocity field from an observed distribution of galaxies in redshift space. The method is based on a kinematic Zel'dovich relation between the velocity and density fields in redshift…

Astrophysics · Physics 2009-10-22 Adi Nusser , Marc Davis

The Cosmological Principle is part of the foundation that underpins the standard model of the Universe. In the era of precision cosmology, when stress tests of the standard model are uncovering various tensions and possible anomalies, it is…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-16 Caroline Guandalin , Jade Piat , Chris Clarkson , Roy Maartens

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…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-18 Oliver T. Oayda , Vasudev Mittal , Geraint F. Lewis

The Cosmological Principle, that the Universe is homogeneous and isotropic on sufficiently large scales, underpins the standard model of cosmology. However, a recent analysis of 1.36 million infrared-selected quasars has identified a…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-08 Lawrence Dam , Geraint F. Lewis , Brendon J. Brewer
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