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A plethora of observational data obtained over the last couple of decades has allowed cosmology to enter into a precision era and has led to the foundation of the standard cosmological constant and cold dark matter paradigm, known as the…

宇宙学与河外天体物理 · 物理学 2021-05-31 Rubén Arjona , Savvas Nesseris

We have assembled a compilation of observational Hubble parameter measurements estimated with the differential evolution of cosmic chronometers, in the redshift range 0<z<1.75. This sample has been used, in combination with CMB data and…

宇宙学与河外天体物理 · 物理学 2013-02-06 Michele Moresco , Licia Verde , Lucia Pozzetti , Raul Jimenez , Andrea Cimatti

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 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…

宇宙学与河外天体物理 · 物理学 2025-09-23 Jie-feng Chen , Tong-Jie Zhang , Peng He , Tingting Zhang , Jie Zhang

We derive new constraints on the Hubble parameter $H_0$ using the available data on $H(z)$ from cosmic chronometers (CCH), and the Hubble rate data points from the supernovae of Type Ia (SnIa) of the Pantheon compilation and the Hubble…

宇宙学与河外天体物理 · 物理学 2019-05-13 Adrià Gómez-Valent , Luca Amendola

Observational growth rate data had been derived from observations of redshift distortions in galaxy redshift surveys. Here we use the growth rate data to place constraints on the dark energy model parameters. By performing a joint analysis…

宇宙学与河外天体物理 · 物理学 2015-06-11 K. Shi , Y. F. Huang , T. Lu

A higher value of Hubble constant has been obtained from measurements with nearby Type Ia supernovae, than that obtained at much higher redshift. With the peculiar motions of their hosts, we find that the matter content at such low redshift…

宇宙学与河外天体物理 · 物理学 2013-07-25 Shuang-Nan Zhang , Yin-Zhe Ma

We propose a novel approach to obtain the growth rate of cosmic structures, $f(z)$, from the evolution of the cosmic homogeneity scale, $R_{\text{H}}(z)$. Our methodology needs two ingredients in a specific functional form:…

宇宙学与河外天体物理 · 物理学 2021-11-29 Felipe Avila , Armando Bernui , Rafael C. Nunes , Edilson de Carvalho , Camila P. Novaes

Recent measurements of the parameters of the Concordance Cosmology Model ($\Lambda$CDM) done in the low-redshift Universe with Supernovae Ia/Cepheids, and in the distant Universe done with Cosmic Microwave Background (CMB) imply different…

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$\alpha$)…

宇宙学与河外天体物理 · 物理学 2018-08-06 Shahab Joudaki , Manoj Kaplinghat , Ryan Keeley , David Kirkby

Gaussian processes provide a method for extracting cosmological information from observations without assuming a cosmological model. We carry out cosmography -- mapping the time evolution of the cosmic expansion -- in a model-independent…

宇宙学与河外天体物理 · 物理学 2012-07-11 Arman Shafieloo , Alex G. Kim , Eric V. Linder

Taking advantage of Gaussian process (GP), we obtain an improved estimate of the Hubble constant, $H_0=70.41\pm1.58$ km s$^{-1}$ Mpc$^{-1}$, using Hubble parameter [$H(z)$] from cosmic chronometers (CCH) and expansion rate function…

宇宙学与河外天体物理 · 物理学 2023-01-26 Yingjie Yang , Xuchen Lu , Lei Qian , Shulei Cao

We propose a non-parametric method of smoothing supernova data over redshift using a Gaussian kernel in order to reconstruct important cosmological quantities including H(z) and w(z) in a model independent manner. This method is shown to be…

天体物理学 · 物理学 2009-11-24 Arman Shafieloo , Ujjaini Alam , Varun Sahni , Alexei A. Starobinsky

Dark energy affects the Hubble expansion rate (namely, the expansion history) $H(z)$ by an integral over $w(z)$. However, the usual observables are the luminosity distances or the angular diameter distances, which measure the…

宇宙学与河外天体物理 · 物理学 2016-03-31 Rui-Yun Guo , Xin Zhang

Recent cosmological observations have achieved high-precision measurements of the Universe's expansion history, prompting the use of nonparametric methods such as Gaussian processes (GP) regression. We apply GP regression for reconstructing…

宇宙学与河外天体物理 · 物理学 2025-11-21 Jia-yan Jiang , Kang Jiao , Tong-Jie Zhang

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…

宇宙学与河外天体物理 · 物理学 2025-01-03 José de Jesús Velázquez , Luis A. Escamilla , Purba Mukherjee , J. Alberto Vázquez

A phenomenological attempt at alleviating the so-called coincidence problem is to allow the dark matter and dark energy to interact. By assuming a coupled quintessence scenario characterized by an interaction parameter $\epsilon$, we…

宇宙学与河外天体物理 · 物理学 2013-06-06 P. C. Ferreira , J. C. Carvalho , J. S. Alcaniz

Several cosmological observations (e.g., Cosmic Microwave Background (CMB), Supernovae Type Ia, and local distance ladder measurements such as Cepheids) have been used to measure the global expansion rate of the Universe, i.e., the Hubble…

We present a model independent method to test the consistency between cosmological measurements of distance and age, assuming the distance duality relation. We use type Ia supernovae, baryon acoustic oscillations, and observational Hubble…

宇宙学与河外天体物理 · 物理学 2015-05-20 Remya Nair , Sanjay Jhingan , Deepak Jain

The consistency of some dynamical dark energy models based on Gauss-Bonnet invariant, ${\cal G}$, is studied compared with cosmological observational tests. The investigated models are modified form of Gauss Bonnet dark energy, MGB-DE and…

广义相对论与量子宇宙学 · 物理学 2019-06-14 Z. Molavi , A. Khodam-Mohammadi