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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…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-31 Rui-Yun Guo , Xin Zhang

The detection of the B-mode polarization of the cosmic microwave background (CMB) by the BICEP2 experiment implies that the tensor-to-scalar ratio $r$ should be involved in the base standard cosmology. In this paper, we extend the…

Cosmology and Nongalactic Astrophysics · Physics 2014-10-20 Jing-Fei Zhang , Jia-Jia Geng , Xin Zhang

The interacting dark energy model could propose a effective way to avoid the coincidence problem. In this paper, dark energy is taken as a fluid with a constant equation of state parameter $w_x$. In a general gauge, we could obtain two sets…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-10 Weiqiang Yang , Lixin Xu

In this work we explore an alternative phenomenological model to Chaplygin gas proposed by H. Hova et. al., consisting on a modification of a perfect fluid, to explain the dynamics of dark matter and dark energy at cosmological scales…

Cosmology and Nongalactic Astrophysics · Physics 2019-01-30 A. Hernandez-Almada , Juan Magana , Miguel A. Garcia-Aspeitia , V. Motta

We use HII starburst galaxy apparent magnitude measurements to constrain cosmological parameters in six cosmological models. A joint analysis of HII galaxy, quasar angular size, baryon acoustic oscillations peak length scale, and Hubble…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-14 Shulei Cao , Joseph Ryan , Bharat Ratra

Current cosmological observations allow for deviations from the standard growth of large-scale structures in the universe. These deviations could indicate modifications to General Relativity on cosmological scales or suggest the dynamical…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-12 Yo Toda , Adrià Gómez-Valent , Kazuya Koyama

Recent Cosmic Microwave Background (CMB) temperature and polarization anisotropy measurements from the Planck mission have significantly improved previous constraints on the neutrino masses as well as the bounds on extended models with…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-20 Eleonora Di Valentino , Elena Giusarma , Olga Mena , Alessandro Melchiorri , Joseph Silk

We present new constraints on coupled dark energy from the recent measurements of the Cosmic Microwave Background Anisotropies from the Planck satellite mission. We found that a coupled dark energy model is fully compatible with the Planck…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-02 Valentina Salvatelli , Andrea Marchini , Laura Lopez-Honorez , Olga Mena

In this paper we use all available baryon acoustic oscillation, Hubble parameter, and quasar angular size data to constrain six dark energy cosmological models, both spatially flat and non-flat. Depending on the model and data combination…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-10 Joseph Ryan , Yun Chen , Bharat Ratra

In this article, we investigate a new parametrization of the dark energy equation of state (EoS) with a single parameter for a barotropic fluid that deviates from the standard $\Lambda$CDM cosmology. We derive observational constraints on…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-31 D. Revanth Kumar , Santosh Kumar Yadav

We constrain plausible dark energy models, parametrized by multiple candidate equation of state, using the recently published Cosmic Microwave Background (CMB) temperature anisotropy data from Planck together with the WMAP-9 low-$\ell$…

Cosmology and Nongalactic Astrophysics · Physics 2015-04-22 Dhiraj Kumar Hazra , Subhabrata Majumdar , Supratik Pal , Sudhakar Panda , Anjan A. Sen

We use Cosmic Microwave Background (CMB) observations together with the Red-sequence Cluster Survey (RCS) weak lensing results to derive constraints on a range of cosmological parameters. This particular choice of observations is motivated…

Astrophysics · Physics 2008-11-26 Carlo R. Contaldi , Henk Hoekstra , Antony Lewis

We explore non-canonical scalar field model in the background of non-flat $D$-dimensional fractal Universe with cosmological constant $\Lambda$ on the condition that the matter and scalar field are separately conserved. The potential $V$,…

General Relativity and Quantum Cosmology · Physics 2019-10-02 Ujjal Debnath , Kazuharu Bamba

We investigate an interacting two-fluid cosmological model and introduce a scalar field representation by means of a linear combination of the individual energy densities. Applying the integrability condition to the scalar field equation we…

Astrophysics · Physics 2008-11-26 Luis Chimento , Monica Forte

Cosmic microwave background measurements have pushed to higher resolution, lower noise, and more sky coverage. These data enable a unique test of the early universe's expansion rate and constituents such as effective number of relativistic…

Cosmology and Nongalactic Astrophysics · Physics 2013-08-05 Alireza Hojjati , Eric V. Linder , Johan Samsing

We compare several well-known cosmological dark energy models using observational data coming both from type Ia supernovae and from Hubble parameter measurements. First we use supernovae data to determine the free parameters of each model…

General Relativity and Quantum Cosmology · Physics 2019-04-30 Grigoris Panotopoulos , Angel Rincon

Constraints on a dark energy dominated Universe are obtained from an interplay between Bayesian Machine Learning and string Swampland criteria. The approach here differs from previous studies, since in the generative process Swampland…

General Relativity and Quantum Cosmology · Physics 2021-05-05 Emilio Elizalde , Martiros Khurshudyan

Risaliti and Lusso have compiled X-ray and UV flux measurements of 1598 quasars (QSOs) in the redshift range $0.036 \leq z \leq 5.1003$, part of which, $z \sim 2.4 - 5.1$, is largely cosmologically unprobed. In this paper we use these QSO…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-28 Narayan Khadka , Bharat Ratra

We consider a model-independent approach to constrain the equivalence redshift, $z_{eq}$, at which dark energy and the total matter (cold dark matter and baryonic) equate their magnitudes. To this aim, in the context of a homogeneous and…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-31 Anna Chiara Alfano , Carlo Cafaro , Salvatore Capozziello , Orlando Luongo

We explore the late time cosmological dynamics of the Universe within the framework of $f(Q,\mathcal{L}_{m})$ gravity by considering the specific form $f(Q, \mathcal{L}_m)=-Q+2\mathcal{L}_m+\gamma$. To describe the cosmic pressure…

General Relativity and Quantum Cosmology · Physics 2025-08-08 Amit Samaddar , S. Surendra Singh