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相关论文: Cardassian Expansion: Constraints from Compact Rad…

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The age of the universe is obtained in a subset of Cardassian models by using WMAP data. Cardassian expansion is a modification to the Friedmann equation that allows the universe to be flat, matter dominated, and accelerating, without a…

天体物理学 · 物理学 2016-08-30 Christopher Savage , Noriyuki Sugiyama , Katherine Freese

I investigate through simulations the redshift dependence of several lensing measures for two cosmological models, a flat universe with a cosmological constant (\LambdaCDM), and an open universe (OCDM). I argue that quintessence models can…

天体物理学 · 物理学 2007-05-23 Antonio C. C. Guimarães

We study the expansion history of the universe up to a redshift of z=1.75 using the 194 recently published SnIa data by Tonry et. al. and Barris et. al. In particular we find the best fit forms of several cosmological models and $H(z)$…

天体物理学 · 物理学 2008-11-26 S. Nesseris , L. Perivolaropoulos

Marginal likelihoods for the cosmic expansion rates are evaluated using the `Constitution' data of 397 supernovas, thereby updating the results in some previous works. Even when beginning with a very strong prior probability that favors an…

宇宙学与河外天体物理 · 物理学 2015-05-18 Moncy V. John

The geometry of the Universe may be probed using the Alcock-Paczynski (AP) effect, in which the observed redshift size of a spherical distribution of sources relative to its angular size varies according to the assumed cosmological model.…

宇宙学与河外天体物理 · 物理学 2021-03-10 Fulvio Melia , Jin Qin , Tong-Jie Zhang

This study investigates the accelerated cosmic expansion within the Ho\v{r}ava-Lifshitz Model. To constrain the cosmological parameters of this model, we incorporate 17 Baryon Acoustic Oscillation points, 31 Cosmic Chronometer points, 40…

宇宙学与河外天体物理 · 物理学 2024-08-16 Himanshu Chaudhary , Ujjal Debnath , Shibesh Kumar Jas Pacif , Niyaz Uddin Molla , G. Mustafa , S. K. Maurya

The LCDM cosmological model assumes the existence of a small cosmological constant in order to explain the observed accelerating cosmic expansion. Despite the dramatic improvement of the quality of cosmological data during the last decade…

宇宙学与河外天体物理 · 物理学 2015-05-18 L. Perivolaropoulos

We show that detailed exploration of the $1<z<2$ redshift region can provide for definitive testing not only of the standard inflationary cosmological paradigm with its fine-tuned cosmological constant and its mysteriously late ($z<1$)…

天体物理学 · 物理学 2009-11-07 Philip D. Mannheim

Infrared magnitude-redshift relations for the 3CR and 6C samples of radio galaxies are presented for a wide range of plausible cosmological models, including those with non-zero cosmological constant OmegaLambda. Variations in the galaxy…

天体物理学 · 物理学 2009-11-07 K. J. Inskip , P. N. Best , M. S. Longair , D. J. C. MacKay

The expectation of explaining cosmological observations without requiring new energy sources is forsooth worthy of investigation. In this letter, a new kind of Cardassian models, called exponential Cardassian models, for the late-time…

天体物理学 · 物理学 2009-11-13 Dao-jun Liu , Chang-bo Sun , Xin-zhou Li

Using the Bayesian theory of model comparison, a new cosmological model due to John and Joseph [M. V. John and K. Babu Joseph, Phys. Rev. D 61, 87304 (2000)] is compared with the standard \Omega_{\Lambda} \neq 0 cosmological model. Their…

天体物理学 · 物理学 2009-11-07 Moncy V. John , J. V. Narlikar

The unknown physical nature of the Dark Energy motivates in cosmology the study of modifications of the gravity theory at large distances. One of these types of modifications is to consider gravity theories, generally termed as $f(R)$. In…

宇宙学与河外天体物理 · 物理学 2022-06-07 Pedro Bessa , Marcela Campista , Armando Bernui

We present measurements of both scale- and time-dependent deviations from the standard gravitational field equations. These late-time modifications are introduced separately for relativistic and non-relativistic particles, by way of the…

宇宙学与河外天体物理 · 物理学 2016-03-16 Andrew Johnson , Chris Blake , Jason Dossett , Jun Koda , David Parkinson , Shahab Joudaki

In this paper, we explore a fractal model of the universe proposed by Calcagni [JHEP{\bf03}(2010)120] for a power-counting renormalizable field theory living in a fractal spacetime. Considering a timelike fractal profile, we derived field…

广义相对论与量子宇宙学 · 物理学 2022-11-01 Mahnaz Asghari , Ahmad Sheykhi

In this paper, we explore how the forthcoming generation of large-scale radio continuum surveys, with the inclusion of some degree of redshift information, can constrain cosmological parameters. By cross-matching these radio surveys with…

宇宙学与河外天体物理 · 物理学 2015-03-20 Stefano Camera , Mário G. Santos , David J. Bacon , Matt J. Jarvis , Kim McAlpine , Ray P. Norris , Alvise Raccanelli , Huub Röttgering

The key probes of the growth of large-scale structure are its rate $f$ and amplitude $\sigma_8$. Redshift space distortions in the galaxy power spectrum allow us to measure only the combination $f\sigma_8$, which can be used to constrain…

宇宙学与河外天体物理 · 物理学 2020-10-14 Louis Perenon , Stéphane Ilić , Roy Maartens , Alvaro de la Cruz-Dombriz

A recently proposed Asymptotically Safe cosmology provides an elegant mechanism towards understanding the nature of dark energy and its associated cosmic coincidence problem. The underlying idea is that the accelerated expansion of the…

宇宙学与河外天体物理 · 物理学 2019-03-06 Fotios K. Anagnostopoulos , Spyros Basilakos , Georgios Kofinas , Vasilios Zarikas

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…

宇宙学与河外天体物理 · 物理学 2018-09-21 Fulvio Melia , Manoj K. Yennapureddy

We study the mutual alignment of radio sources within two surveys, FIRST and TGSS. This is done by producing two position angle catalogues containing the preferential directions of respectively $30\,059$ and $11\,674$ extended sources…

宇宙学与河外天体物理 · 物理学 2017-09-12 O. Contigiani , F. de Gasperin , G. K. Miley , L. Rudnick , H. Andernach , J. K. Banfield , A. D. Kapińska , S. S. Shabala , O. I. Wong

The cosmic microwave background (CMB) and baryon acoustic oscillations (BAO) provide precise measurements of the cosmic expansion history through the comoving acoustic scale. The CMB angular scale measurement $\theta_*$ is particularly…

宇宙学与河外天体物理 · 物理学 2025-04-24 Antony Lewis , Ewan Chamberlain