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We critically examine recent claims challenging the viability of the G-step model (GSM) as a solution to the Hubble tension. The GSM proposes a $\sim$4 % increase in the effective gravitational constant $G_{\text{eff}}$ beyond $z \approx…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-07 Leandros Perivolaropoulos , Ruchika

In this paper, a parametrization describing the kinematical state of the universe via cosmographic approach is considered, where the minimum input is the assumption of the cosmological principle, i.e. the Friedmann-Robertson-Walker metric.…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Lixin Xu , Yuting Wang

Reconstructing the evolution history of the dark energy equation of state parameter $w(z)$ directly from observational data is highly valuable in cosmology, since it contains substantial clues in understanding the nature of the accelerated…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-31 Zhi-E Liu , Hao-Ran Yu , Tong-Jie Zhang , Yan-Ke Tang

We describe regularized methods for image reconstruction and focus on the question of hyperparameter and instrument parameter estimation, i.e. unsupervised and myopic problems. We developed a Bayesian framework that is based on the \post…

Instrumentation and Methods for Astrophysics · Physics 2012-11-16 F. Orieux , J. -F. Giovannelli , T. Rodet , A. Abergel

A key challenge in spatial statistics is the analysis for massive spatially-referenced data sets. Such analyses often proceed from Gaussian process specifications that can produce rich and robust inference, but involve dense covariance…

Methodology · Statistics 2019-07-25 Shinichiro Shirota , Andrew O. Finley , Bruce D. Cook , Sudipto Banerjee

Gaussian process regression is a powerful Bayesian nonlinear regression method. Recent research has enabled the capture of many types of observations using non-Gaussian likelihoods. To deal with various tasks in spatial modeling, we benefit…

Machine Learning · Statistics 2025-08-26 Yuta Shikuri

In this work, we reconstruct the H(z) based on observational Hubble data with Artificial Neural Network, then estimate the cosmological parameters and the Hubble constant. The training data we used are covariance matrix and mock H(z), which…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-23 Jie-feng Chen , Tong-Jie Zhang , Peng He , Tingting Zhang , Jie Zhang

By incorporating the curvature $\Omega_k$ as a free parameter, it has been found that the tension between the high redshift CMB shift parameter $R(z^{\ast})$ data and the low redshift SNIa and BAO data from the combination of SDSS and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Jianmang Lin , Puxun Wu , Hongwei Yu

Strong gravitational lensing provides a natural opportunity to test General Relativity (GR). We propose a model-independent method for simultaneous constraining on Hubble constant ($H_0$) and post-Newtonian parameter (${\gamma_{\rm{PPN}}}$)…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-30 Tonghua Liu , Kai Liao

For a large class of dark energy (DE) models, for which the effective gravitational constant is a constant and there is no direct exchange of energy between DE and dark matter (DM), knowledge of the expansion history suffices to reconstruct…

Astrophysics · Physics 2010-05-27 Ujjaini Alam , Varun Sahni , Alexei A. Starobinsky

The use of Gaussian processes (GPs) is supported by efficient sampling algorithms, a rich methodological literature, and strong theoretical grounding. However, due to their prohibitive computation and storage demands, the use of exact GPs…

Statistics Theory · Mathematics 2022-07-27 Kelly R. Moran , Matthew W. Wheeler

We examine how dark energy constraints from current observational data depend on the analysis methods used: the analysis of Type Ia supernovae (SNe Ia), and that of galaxy clustering data. We generalize the flux-averaging analysis method of…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Yun Wang , Chia-Hsun Chuang , Pia Mukherjee

We perform a comprehensive study of the dark energy equation of state (EoS) utilizing the model-independent Gaussian processes (GP). Using a combination of the Union 2.1 data set, the 30 newly added H(z) cosmic chronometer data points and…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-28 Deng Wang , Xin-He Meng

We introduce a new scalable approximation for Gaussian processes with provable guarantees which hold simultaneously over its entire parameter space. Our approximation is obtained from an improved sample complexity analysis for sparse…

Machine Learning · Computer Science 2020-11-18 Quang Minh Hoang , Trong Nghia Hoang , Hai Pham , David P. Woodruff

Future NASA lander missions to icy moons will require completely automated, accurate, and data efficient calibration methods for the robot manipulator arms that sample icy terrains in the lander's vicinity. To support this need, this paper…

Robotics · Computer Science 2023-03-08 Ersin Daş , Joel W. Burdick

Obtaining accurate estimates of satellite drag coefficients in low Earth orbit is a crucial component in positioning and collision avoidance. Simulators can produce accurate estimates, but their computational expense is much too large for…

Computation · Statistics 2019-06-25 Furong Sun , Robert B. Gramacy , Benjamin Haaland , Earl Lawrence , Andrew Walker

The kinematic expansion history of the universe is investigated by using the 307 supernovae type Ia from the Union Compilation set. Three simple model parameterizations for the deceleration parameter (constant, linear and abrupt transition)…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-13 A. C. C. Guimarães , J. V. Cunha , J. A. S. Lima

We measure cosmological parameters using the three-dimensional power spectrum P(k) from over 200,000 galaxies in the Sloan Digital Sky Survey (SDSS) in combination with WMAP and other data. Our results are consistent with a ``vanilla'' flat…

Due to their conjugate posteriors, Gaussian process priors are attractive for estimating the drift of stochastic differential equations with continuous time observations. However, their performance strongly depends on the choice of the…

Statistics Theory · Mathematics 2020-02-04 Jan van Waaij

In this study, we explore model independent constraints on the universe kinematics up to the snap and jerk hierarchical terms. To do so, we consider the latest Baryon Acoustic Oscillation (BAO) release provided by the DESI collaboration,…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-11 Orlando Luongo , Marco Muccino