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This article questions the common assumption of cold dark matter (DM) by exploring the possibility of a non-zero equation of state (EoS) without relying on any parametric approach. In standard cosmological analyses, DM is typically modeled…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-01 Mazaharul Abedin , Luis A. Escamilla , Supriya Pan , Eleonora Di Valentino , Weiqiang Yang

Much focus was on the possible slowing down of cosmic acceleration under the dark energy parametrization. In the present paper, we investigate this subject using the Gaussian processes (GP), without resorting to a particular template of…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-07 Ming-Jian Zhang , Jun-Qing Xia

We apply Gaussian processes (GP) in order to impose constraints on teleparallel gravity and its $f(T)$ extensions. We use available $H(z)$ observations from (i) cosmic chronometers data (CC); (ii) Supernova Type Ia (SN) data from the…

General Relativity and Quantum Cosmology · Physics 2021-02-03 Rebecca Briffa , Salvatore Capozziello , Jackson Levi Said , Jurgen Mifsud , Emmanuel N. Saridakis

We investigate a phenomenological non-gravitational coupling between dark energy and dark matter, where the interaction in the dark sector is parameterized as an energy transfer either from dark matter to dark energy or the opposite. The…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-11 Riccardo Murgia , Stefano Gariazzo , Nicolao Fornengo

Bayesian Machine Learning~(BML) and strong lensing time delay~(SLTD) techniques are used in order to tackle the $H_{0}$ tension in $f(T)$ gravity. The power of BML relies on employing a model-based generative process which already plays an…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-31 Muhsin Aljaf , Emilio Elizalde , Martiros Khurshudyan , Kairat Myrzakulov , Aliya Zhadyranova

Cosmological models describing the non-gravitational interaction between dark matter and dark energy are based on some phenomenological choices of the interaction rates between dark matter and dark energy. There is no such guiding rule to…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-10 Supriya Pan , German S. Sharov , Weiqiang Yang

The recent observational evidence for the current cosmic acceleration have stimulated renewed interest in alternative cosmologies, such as scenarios with interaction in the dark sector (dark matter and dark energy). In general, such models…

Cosmology and Nongalactic Astrophysics · Physics 2009-10-22 R. S. Goncalves , J. S. Alcaniz , A. Dev , D. Jain

Gaussian processes are a fully Bayesian smoothing technique that allows for the reconstruction of a function and its derivatives directly from observational data, without assuming a specific model or choosing a parameterization. This is…

Cosmology and Nongalactic Astrophysics · Physics 2013-11-27 Marina Seikel , Chris Clarkson

Within the framework of Unimodular Gravity, we consider non-gravitational interactions between dark matter and dark energy. Particularly, we describe such interactions in the dark sector by considering diffusion models that couple the cold…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-31 Francisco X. Linares Cedeño , Ulises Nucamendi

Decaying dark matter models provide a physically motivated way of channeling energy between the matter and radiation sectors. In principle, this could affect the predicted value of the Hubble constant in such a way as to accommodate the…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-04 Emil Brinch Holm , Thomas Tram , Steen Hannestad

We present a nonparametric approach to reconstruct the interaction between dark energy and dark matter directly from SNIa Union 2.1 data using Gaussian processes, which is a fully Bayesian approach for smoothing data. In this method, once…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-26 Tao Yang , Zong-Kuan Guo , Rong-Gen Cai

With the emersion of precise cosmology and the emergence of cosmic tensions, we are faced with the question of whether the simple model of cold dark matter needs to be extended and whether doing so can alleviate the tensions and improve our…

High Energy Physics - Phenomenology · Physics 2023-07-18 Parisa Arabameri , Zahra Davari , Nima Khosravi

The non-gravitational interaction between the dark components of the Universe could lead to the variation of dark matter energy density standard evolution law. When we assume this scenario, the dark matter energy density follows…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-27 Z. C. Santana , M. O. Costa , R. F. L. Holanda , R. Silva

Embedding non-restrictive prior knowledge, such as energy conservation laws, into learning methods is a key motive to construct physically consistent dynamics models from limited data, relevant for, e.g., model-based control. Recent work…

Machine Learning · Computer Science 2026-04-16 Jan-Hendrik Ewering , Robin E. Herrmann , Niklas Wahlström , Thomas B. Schön , Thomas Seel

In this study, we introduce a novel analytical Gaussian Process (GP) cosmography methodology, leveraging the differentiable properties of GPs to derive key cosmological quantities analytically. Our approach combines cosmic chronometer (CC)…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-19 Bikash R. Dinda

The standard Lambda cold dark matter ($\Lambda$CDM) paradigm of the physical Universe suffers from well-known conceptual problems and is challenged by observational data. Alternative models exist in the literature, both phenomenological and…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-13 D. Castelão , I. Tereno

In this work, we study the extended viscous dark energy models in the context of matter perturbations. To do this, we assume an alternative interpretation of the flat Friedmann-Lema\^itre-Robertson-Walker Universe, through the nonadditive…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-13 W. J. C. da Silva , R. Silva

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

In this work, we first discuss the possibility that dark energy models with negative energy density values in the past can alleviate the $H_0$ tension, as well as the discrepancy with the baryon acoustic oscillation (BAO) Lyman-$\alpha$…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-09 Giovanni Acquaviva , Ozgur Akarsu , Nihan Katirci , J. Alberto Vazquez

The rising concern in the Hubble constant tension ($H_0$ tension) of the cosmological models motivates the scientific community to search for alternative cosmological scenarios that could resolve the $H_0$ tension. In this regard, we aim to…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-06 Sanjay Mandal , Oleksii Sokoliuk , Sai Swagat Mishra , P. K. Sahoo