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Dark energy could actually be the manifestation of a modification to the Friedmann equation arising from new physics (e.g., extra dimensions). Writing the correction as $(1-\Omega_M)H^\alpha /H_0^{\alpha -2}$, we explore the phenomenology…

Astrophysics · Physics 2007-05-23 Gia Dvali , Michael S. Turner

One of the principal goals of modern cosmology is to constrain the properties of dark energy. At present, numerous surveys are aiming to determine the equation of state, which is assumed constant due to our poor understanding of its…

Astrophysics · Physics 2009-11-10 Fergus Simpson , Sarah Bridle

An important issue in cosmology is reconstructing the effective dark energy equation of state directly from observations. With so few physically motivated models, future dark energy studies cannot only be based on constraining a dark energy…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Chris Clarkson , Caroline Zunckel

We use the current weak lensing data to constrain the equation of state of dark energy $w$ and the total mass of massive neutrinos $\sum m_{\nu}$. The constraint on $w$ would be weak if only the current weak lensing data are used. With the…

Astrophysics · Physics 2008-10-21 Yan Gong , Tong-Jie Zhang , Tian Lan , Xue-Lei Chen

The red-shift space distortions in the galaxy power spectrum can be used to measure the growth rate of matter density perturbations delta_m. For dynamical dark energy models in General Relativity we provide a convenient analytic formula of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Shinji Tsujikawa , Antonio De Felice , Jailson Alcaniz

We present an analysis of the constraining power of future measurements of the Integrated Sachs-Wolfe (ISW) effect on models of the equation of state of dark energy as a function of redshift, w(z). To achieve this, we employ a new…

The conceptual difficulties associated with a cosmological constant have led to the investigation of alternative models in which the equation of state parameter, $w=p/\rho$, of the dark energy evolves with time. We show that combining the…

Astrophysics · Physics 2007-05-23 H. K. Jassal , J. S. Bagla , T. Padmanabhan

The time dependence of the dark energy density can be an important clue to the nature of dark energy in the universe. We show that future supernova data from dedicated telescopes (such as SNAP), when combined with data of nearby supernovae,…

Astrophysics · Physics 2014-10-13 Yun Wang , Veselin Kostov , Katherine Freese , Joshua A. Frieman , Paolo Gondolo

Detecting dark energy dynamics is the main quest of current dark energy research. Addressing the issue demands a fully consistent analysis of CMB, large scale structure and SN-Ia data with multi-parameter freedom valid for all redshifts.…

Astrophysics · Physics 2008-11-26 P. S. Corasaniti , M. Kunz , D. Parkinson , E. J. Copeland , B. A. Bassett

Constrains of dark energy (DE) at high redshift from current and mock future observational data are obtained. It is found that present data give poor constraints of DE even beyond redshift z=0.4, and mock future 2298 type Ia supernove data…

Cosmology and Nongalactic Astrophysics · Physics 2014-08-26 Qiping Su , Rong-Gen Cai

We use the recent type Ia supernova, cosmic microwave background and large-scale structure data to shed light on the temporal evolution of the dark energy equation of state $w(z)$ out to redshift one. We constrain the most flexible…

Astrophysics · Physics 2008-11-26 Gong-Bo Zhao , Dragan Huterer , Xinmin Zhang

Current cosmological observations show a strong signature of the existence of a dark energy component with negative pressure. The most obvious candidate for this dark energy is the cosmological constant (with the equation of state…

Astrophysics · Physics 2008-11-26 T. Padmanabhan , T. Roy Choudhury

We present constraints on the dark energy equation-of-state parameter, w=P/(rho c^2), using 60 Type Ia supernovae (SNe Ia) from the ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat…

We reconstruct the equation of state $w(z)$ of dark energy (DE) using a recently released data set containing 172 type Ia supernovae without assuming the prior $w(z) \geq -1$ (in contrast to previous studies). We find that dark energy…

Astrophysics · Physics 2009-11-10 Ujjaini Alam , Varun Sahni , Tarun Deep Saini , A. A. Starobinsky

Dark energy is the invisible fuel that seems to drive the current acceleration of the Universe. Its presence, which is inferred from an impressive convergence of high-quality observational results along with some sucessful theoretical…

Astrophysics · Physics 2008-11-26 M. A. Dantas , J. S. Alcaniz , Deepak Jain , Abha Dev

Accurate predictions on non--linear power spectra, at various redshift z, will be a basic tool to interpret cosmological data from next generation mass probes, so obtaining key information on Dark Energy nature. This calls for high…

Astrophysics · Physics 2011-03-15 Luciano Casarini , Andrea V. Maccio' , Silvio A. Bonometto

The model-independent piecewise parametrizations (0-spline, linear-spline and cubic-spline) are used to estimate constraints of equation of state of dark energy ($w_{de}$) from current observational data (including SNIa, BAO and Hubble…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-11 Qiping Su , Xi He , Rong-Gen Cai

We perform a cosmological parameter analysis of the 75 square degree CTIO lensing survey in conjunction with CMB and Type Ia supernovae data. For Lambda CDM cosmologies, we find that the amplitude of the power spectrum at low redshift is…

Astrophysics · Physics 2008-11-26 Mike Jarvis , Bhuvnesh Jain , Gary Bernstein , Derek Dolney

The variation of dark energy density with redshift, $\rho_X(z)$, provides a critical clue to the nature of dark energy. Since $\rho_X(z)$ depends on the dark energy equation of state $w_X(z)$ through an integral, $\rho_X(z)$ can be…

Astrophysics · Physics 2009-11-10 Yun Wang , Katherine Freese

We investigate dynamical behavior of the equation of state of dark energy $w_{de}$ by employing the linear-spline method in the region of low redshifts from observational data (SnIa, BAO, CMB and 12 $H(z)$ data). The redshift is binned and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Rong-Gen Cai , Qiping Su , Hong-Bo Zhang