59 citations · 103 across the 16 of their papers we have counts for
9 papers · 1 filter
Wising up to CatWISE: using simulation-based inference to interpret the ecliptic bias and confirm the cosmic dipole excess
Oliver T. Oayda, Geraint F. Lewis
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')…
Local environmental dependence on weak-lensing shear statistics
Sonia Akter Ema, Md Rasel Hossen, Krzysztof Bolejko +1
Despite the assumption that an ideal FLRW observer is not dependent on the local environment, observations are biased by the positions of the observers due to the matter correlatio…
Cosmic Multipoles in Galaxy Surveys II: Comparing Different Methods in Assessing the Cosmic Dipole
Vasudev Mittal, Oliver T. Oayda, Geraint F. Lewis
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 numb…
Revisiting The Cosmological Time Dilation of Distant Quasars: Influence of Source Properties and Evolution
Brendon J. Brewer, Geraint F. Lewis, Yuan Li
After decades of searching, cosmological time dilation was recently identified in the timescale of variability seen in distant quasars. Here, we expand on the previous analysis to…
Cosmic Multipoles in Galaxy Surveys Part I: How Inferences Depend on Source Counts and Masks
Oliver T. Oayda, Vasudev Mittal, Geraint F. Lewis
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…
A Bayesian approach to the cosmic dipole in radio galaxy surveys: Joint analysis of NVSS & RACS
Oliver T. Oayda, Vasudev Mittal, Geraint F. Lewis +1
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 bet…
The Cosmic Dipole in the Quaia Sample of Quasars: A Bayesian Analysis
Vasudev Mittal, Oliver T. Oayda, Geraint F. Lewis
We present a Bayesian analysis of the Quaia sample of 1.3 million quasars as a test of the cosmological principle. This principle postulates that the universe is homogeneous and is…
Big Bang Nucleosynthesis Initial Conditions: Revisiting Wagoner et al. (1967)
Charlie Sharpe, Geraint F. Lewis, Luke A. Barnes
We revisit Wagoner et al. (1967), a classic contribution in the development of Big Bang Nucleosynthesis. We demonstrate that it presents an incorrect expression for the temperature…
Nonlinear Chaplygin Gas Cosmologies
P. P. Avelino, K. Bolejko, G. F. Lewis
We study the nonlinear regime of Unified Dark Energy models, using Generalized Chaplygin Gas cosmologies as a representative example, and introduce a new parameter characterizing t…