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A method of general applicability has been developed, whereby the null geodesic equations of the Einstein-Straus-de Sitter metric can be integrated simultaneously in terms of the curvature constant $k$. The purpose is to generalize the…

General Relativity and Quantum Cosmology · Physics 2024-09-06 Mourad Guenouche

An important concern in the application of gamma-ray bursts (GRBs) to cosmology is that the calibration of GRB luminosity/energy relations depends on the cosmological model, due to the lack of a sufficient low-redshift GRB sample. In this…

Astrophysics · Physics 2009-11-13 Nan Liang , Wei Ke Xiao , Yuan Liu , Shuang Nan Zhang

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…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-05 S. Ilani Loubser , Adebusola B. Alabi , Matt Hilton , Yin-Zhe Ma , Xin Tang , Narges Hatamkhani , Catherine Cress , Rosalind E. Skelton , S. Andile Nkosi

The cosmic microwave background (CMB) monopole temperature evolves with the inverse of the cosmological scale factor, independent of many cosmological assumptions. With sufficient sensitivity, real-time cosmological observations could thus…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-14 Maximilian H. Abitbol , J. Colin Hill , Jens Chluba

Supernova Ia magnitude surveys measure the dimensionless luminosity distance $H_{0}D_{L}$. However, from the distances alone one cannot obtain quantities like $H(z)$ or the dark energy equation of state, unless further cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-30 Luca Amendola , Miguel Quartin

We present a new model-independent strategy for testing the Friedmann-Lema\^{\i}tre-Robertson-Walker metric and constraining cosmic curvature, based on future time delay measurements of strongly lensed quasar-elliptical galaxy systems from…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-20 Kai Liao , Zhengxiang Li , Guo-Jian Wang , Xi-Long Fan

In this paper, we present a scheme to investigate the opacity of the Universe in a cosmological-model-independent way, with the combination of current and future measurements of type Ia supernova sample and galactic-scale strong…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-08 Yu-Bo Ma , Shuo Cao , Jia Zhang , Jingzhao Qi , Tonghua Liu , Yuting Liu , Shuaibo Geng

The presence of inhomogeneities modifies the cosmic distances through the gravitational lensing effect, and, indirectly, must affect the main cosmological tests. Assuming that the dark energy is a smooth component, the simplest way to…

Astrophysics · Physics 2008-11-26 R. C. Santos , J. V. Cunha , J. A. S. Lima

We use three different data sets, specifically $H(z)$ measurements from cosmic chronometers, the HII-galaxy Hubble diagram, and reconstructed quasar-core angular-size measurements, to perform a joint analysis of three flat cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-01 Hao-Yi Wan , Shu-Lei Cao , Fulvio Melia , Tong-Jie Zhang

Cosmological models and their parameters are widely debated, especially about whether the current discrepancy between the values of the Hubble constant, $H_{0}$, obtained by type Ia supernovae (SNe Ia), and the Planck data from the Cosmic…

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

Deriving the expansion history of the Universe is a major goal of modern cosmology. To date, the most accurate measurements have been obtained with Type Ia Supernovae and Baryon Acoustic Oscillations, providing evidence for the existence of…

In this paper, we present a model-independent approach to calibrate the largest quasar sample. Calibrating quasar samples is essentially constraining the parameters of the linear relation between the $\log$ of the ultraviolet (UV) and X-ray…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-11 Xiaolei Li , Ryan E. Keeley , Arman Shafieloo , Xiaogang Zheng , Shuo Cao , Marek Biesiada , Zong-Hong Zhu

Using measurements of $H(z)$ and $d_\mathrm{A}(z)$ from the Baryon Oscillation Spectroscopic Survey (BOSS) DR12 and luminosity distances from the Joint Lightcurve Analysis (JLA) compilation of supernovae (SN), we measure $H_0 r_\mathrm{d}$…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-12 Benjamin L'Huillier , Arman Shafieloo

In the realm of the $\omega$CDM cosmological model with quiescence or quintessence as the dark energy, characterized by $\omega>-1$, there exists a fixed value of $H(z)$ at $z=-1$, devoid of dependency on other cosmological parameters. To…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-16 Cheqiu Lyu , Wei Hong , Tong-Jie Zhang

Recent measurements of the cosmic microwave background (CMB) radiation have shown an apparent tension with the present value of the Hubble parameter inferred from local observations of supernovae, which look closer, i.e. brighter, than what…

Cosmology and Nongalactic Astrophysics · Physics 2016-07-29 Antonio Enea Romano , Sergio Andrés Vallejo

The $L-\sigma$ relation of HII galaxies (HIIGx) calibrated by a distance indicator is a reliable standard candle for measuring the Hubble constant $H_0$. The most straightforward calibration technique anchors them with the first tier of…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-13 Jian-Chen Zhang , Kang Jiao , Tingting Zhang , Tong-Jie Zhang , Bo 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

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 paper, we present a cosmological model-independent test for the cosmic opacity at high redshifts ($z\sim5$). We achieve this with the opacity-dependent luminosity distances derived from nonlinear relation between X-ray and UV…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-19 Tonghua Liu , Shuo Cao , Marek Biesiada , Yuting Liu , Shuaibo Geng , Yujie Lian