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The Hubble constant $H_0$ tension has emerged as the most serious crisis in modern cosmology, potentially indicating that the $\Lambda$CDM model may not describe our universe accurately. In this paper, we establish a new,…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-26 Yang Liu , Bao Wang , Hongwei Yu , Puxun Wu

The use of Gaussian Processes with a measurement of the cosmic expansion rate based solely on the observation of cosmic chronometers provides a completely cosmology-independent reconstruction of the Hubble constant H(z) suitable for testing…

Cosmology and Nongalactic Astrophysics · Physics 2018-09-21 Fulvio Melia , Manoj K. Yennapureddy

In the context of cosmography approach and using the data of Hubble diagram for supernovae, quasars and gamma-ray bursts, we study some DE parametrizations and also the concordance $\Lambda$CDM universe. Using the different combinations of…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-09 Mehdi Rezaei , Saeed Pour Ojaghi , Mohammad Malekjani

We constrain the parameters describing the kinematical state of the universe using a cosmographic approach, which is fundamental in that it requires a very minimal set of assumptions (namely to specify a metric) and does not rely on the…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Vincenzo Vitagliano , Jun-Qing Xia , Stefano Liberati , Matteo Viel

Cosmic chronometers offer a model-independent way to trace the expansion history of the Universe via the dating of passively evolving objects. This enables testing the validity of cosmological models without concrete assumptions of their…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-05 Carlos A. Álvarez , Marcos M. Cueli , Alessandro Bressan , Lumen Boco , Balakrishna S. Haridasu , Michele Bosi , Luigi Danese , Andrea Lapi

Despite the broad successes of the flat $\Lambda$CDM model and its fitness to the various cosmological observations, it confronts challenges stemming from anomalies in the measurements of the Hubble constant ($H_0$) and the amplitude of…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-28 Saeed Pourojaghi , Mohammad Malekjani

The challenging issue of determining the correct $f(R)$ among several possibilities is here revised by means of numerical reconstructions of the modified Friedmann equations around the redshift interval $z\in[0,1]$. Frequently, a severe…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-24 Liberato Pizza

Context. Explaining the accelerated expansion of the Universe is one of the fundamental challenges in physics today. Cosmography provides information about the evolution of the universe derived from measured distances, assuming only that…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-05 Marek Demianski , Ester Piedipalumbo , Disha Sawant , Lorenzo Amati

We analyze how predictions of cosmological models depend on a choice of described observational data, restrictions on flatness, and how this choice can alleviate the $H_0$ tension. These effects are demonstrated in the $w$CDM model in…

General Relativity and Quantum Cosmology · Physics 2020-02-11 G. S. Sharov , E. S. Sinyakov

We model the expansion history of the Universe as a Gaussian Process and find constraints on the dark energy density and its low-redshift evolution using distances inferred from the Luminous Red Galaxy (LRG) and Lyman-alpha (Ly$\alpha$)…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-06 Shahab Joudaki , Manoj Kaplinghat , Ryan Keeley , David Kirkby

Model-independent methods in cosmology has become an essential tool in order to deal with an increasing number of theoretical alternatives for explaining the late-time acceleration of the Universe. In principle, this provides a way of…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-13 Vinicius C. Busti , Peter K. S. Dunsby , Alvaro de la Cruz-Dombriz , Diego Saez-Gomez

We present a cosmographic study designed to test the simplest type of accelerating cosmology: a flat universe with matter and a cosmological constant ($\Lambda$). Hubble series expansions are fit to the SCP Union2.1 supernova data set to…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-17 Brett Bochner , Damon Pappas , Menglu Dong

A natural extension of the standard cosmological model are models that include curvature as a free parameter. In this work we study in detail the observational constraints on the non-flat $\Lambda CDM$ model using the two main geometric…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-15 Velasquez-Toribio , A. M , Magnago , A. dos R

The current tension between early- and late-Universe measurements of the Hubble constant ($H_0$), along with the still elusive nature of dark matter and dark energy, calls for model-independent probes of the Universe's expansion history.…

In the current work, we have implemented an extension of the standard Gaussian Process formalism, namely the Multi-Task Gaussian Process with the ability to perform a joint learning of several cosmological data simultaneously. We have…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-15 Balakrishna S. Haridasu , Vladimir V. Luković , Michele Moresco , Nicola Vittorio

In the last dozen years a wide and variegated mass of observational data revealed that the universe is now expanding at an accelerated rate. In the absence of a well-based theory to interpret the observations, cosmography provides…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-30 Ester Piedipalumbo , Enrica Della Moglie , Roberto Cianci

In this article, we elaborate further on the $\Lambda$CDM "tension", suggested recently by the authors \cite{Lusso:2019akb,Risaliti:2018reu}. We combine Supernovae type Ia (SNIa) with quasars (QSO) and Gamma Ray Bursts (GRB) data in order…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-21 Ahmad Mehrabi , Spyros Basilakos

In this work we use cosmography to alleviate the degeneracy among cosmological models, proposing a way to parameterize matter and dark energy in terms of cosmokinematics quantities. The recipe of using cosmography allows to expand…

General Relativity and Quantum Cosmology · Physics 2015-12-23 Orlando Luongo , Giovanni Battista Pisani , Antonio Troisi

The current accelerated expansion of the Universe remains ones of the most intriguing topics in modern cosmology, driving the search for innovative statistical techniques. Recent advancements in machine learning have significantly enhanced…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-03 José de Jesús Velázquez , Luis A. Escamilla , Purba Mukherjee , J. Alberto Vázquez

We use cosmography to present constraints on the kinematics of the Universe, without postulating any underlying theoretical model. To this end, we use a Monte Carlo Markov Chain analysis to perform comparisons to the supernova Ia Union 2…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Alejandro Aviles , Christine Gruber , Orlando Luongo , Hernando Quevedo