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The energy density of a scalar field $\phi$ with potential $V(\phi) \propto \phi^{-\alpha}$, $\alpha > 0$, behaves like a time-variable cosmological constant that could contribute significantly to the present energy density. Predictions of…

Astrophysics · Physics 2009-10-31 Silviu Podariu , Bharat Ratra

We have previously shown that the type Ia supernovae data by Riess et al. match the prediction of the magnitude-redshift relation in the plasma-redshift cosmology. In this article, we also show that the recent SNLS data, which have a…

Astrophysics · Physics 2007-05-23 Ari Brynjolfsson

We review the use of Type Ia supernovae for cosmological distance determinations. Low-redshift SNe Ia (z < 0.1) demonstrate that the Hubble expansion is linear, that H_0 = 65 +/- 2 (statistical) km/s/Mpc, and that the properties of dust in…

Astrophysics · Physics 2009-10-31 A. V. Filippenko , A. G. Riess

Dark energy and the accelerated expansion of the universe have been the direct predictions of the distant supernovae Ia observations which are also supported, indirectly, by the observations of the CMB anisotropies, gravitational lensing…

Astrophysics · Physics 2008-11-26 Ram Gopal Vishwakarma

Upcoming photometric surveys will discover tens of thousands of Type Ia supernovae (SNe Ia), vastly outpacing the capacity of our spectroscopic resources. In order to maximize the science return of these observations in the absence of…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-11 Helen Qu , Masao Sako

Model-independent constraints on the spatial curvature are not only closely related to important problems such as the evolution of the Universe and properties of dark energy, but also provide a test of the validity of the fundamental…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-28 Zhengxiang Li , Xuheng Ding , Guo-Jian Wang , Kai Liao , Zong-Hong Zhu

The empirical evidences in favor of the hypothesis that the speed of light decreases by a few centimeters per second each year are examined. Lunar laser ranging data are found to be consistent with this hypothesis, which also provides a…

General Physics · Physics 2009-12-16 Yves-Henri Sanejouand

I discuss the use of Type Ia supernovae (SNe Ia) for cosmological distance determinations. Low-redshift SNe Ia (z < 0.1) demonstrate that the Hubble expansion is linear with H_0 = 72 +/- 8 km/s/Mpc, and that the properties of dust in other…

Astrophysics · Physics 2015-11-11 Alexei V. Filippenko

Contemporary observational and theoretical studies on the temporal nature of microscopic measurements renewed the discussion about the fundamental constants, leading to the possibility of light speed variation and superluminal pulse…

General Physics · Physics 2007-05-23 R Assumpcao

Recent attempts at measuring the variation of $c$ using an assortment of standard candles and the redshift-dependent Hubble expansion rate inferred from the currently available catalog of cosmic chronometers have tended to show that the…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-18 Fulvio Melia

The surprising discovery of an accelerating universe led cosmologists to posit the existence of "dark energy"--a mysterious energy field that permeates the universe. Understanding dark energy has become the central problem of modern…

The Hubble constant ($H_0$) is one of the fundamental parameters in cosmology, but there is a heated debate around the $>$4$\sigma$ tension between the local Cepheid distance ladder and the early Universe measurements. Strongly lensed Type…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-14 S. Huber , S. H. Suyu , D. Ghoshdastidar , S. Taubenberger , V. Bonvin , J. H. H. Chan , M. Kromer , U. M. Noebauer , S. A. Sim , L. Leal-Taixé

Supernovae Ia (SNe Ia) light curves have been used to prove the universe is expanding. As standard candles, SNe Ia appear to indicate the rate of expansion has increased in the past and is now decreasing. This independent evaluation of SNe…

Astrophysics · Physics 2007-05-23 Jerry W. Jensen

Brighter Type Ia supernovae (SNe Ia) have broader, more slowly declining B-band light curves than dimmer SNe Ia. We study the physical origin of this width-luminosity relation (WLR) using detailed radiative transfer calculations of…

Astrophysics · Physics 2008-11-26 Daniel Kasen , S. E. Woosley

The properties of the highest velocity ejecta of normal Type Ia supernovae (SNe Ia) are studied via models of very early optical spectra of 6 SNe. At epochs earlier than 1 week before maximum, SNe with a rapidly evolving Si II 6355 line…

Data from spacecrafts tracking exhibit many anomalies that suggest the dependence of the speed of electromagnetic radiation with the motion of its source. This dependence is different from that predicted from emission theories that long ago…

Classical Physics · Physics 2016-07-26 Luis Bilbao

Observations of high-redshift supernovae indicate that the universe is accelerating. Here we present a {\em model-independent} method for estimating the form of the potential $V(\phi)$ of the scalar field driving this acceleration, and the…

Astrophysics · Physics 2009-10-31 Tarun Deep Saini , Somak Raychaudhury , Varun Sahni , A. A. Starobinsky

Context. The precise determination of the present-day expansion rate of the Universe, expressed through the Hubble constant $H_0$, is one of the most pressing challenges in modern cosmology. Assuming flat $\Lambda$CDM, $H_0$ inference at…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-21 S. Taubenberger , S. H. Suyu , E. Komatsu , I. Jee , S. Birrer , V. Bonvin , F. Courbin , C. E. Rusu , A. J. Shajib , K. C. Wong

We use type-Ia supernovae (SNe Ia) discovered by the SDSS-II SN Survey to search for dependencies between SN Ia properties and the projected distance to the host galaxy center, using the distance as a proxy for local galaxy properties…

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