相关论文: Constraints on the Physical Parameters of the Dark…
Understanding the acceleration of the universe and its cause is one of the key problems in physics and cosmology today, and is best studied using a variety of mutually complementary approaches. Daly and Djorgovski (2003, 2004) proposed a…
We extend and apply a model-independent analysis method developed earlier by Daly & Djorgovski to new samples of supernova standard candles, radio galaxy and cluster standard rulers, and use it to constrain physical properties of the dark…
Understanding of the nature of dark energy, which appears to drive the expansion of the universe, is one of the central problems of physical cosmology today. In an earlier paper [Daly & Djorgovski (2003)] we proposed a novel method to…
One of the goals of current cosmological studies is the determination of the expansion and acceleration rates of the universe as functions of redshift, and the determination of the properties of the dark energy that can explain these…
We describe a method to derive the expansion and acceleration rates directly from the data, without the need for the specification of a theory of gravity, and without adopting an a priori parameterization of the form or redshift evolution…
Determination of the expansion and acceleration history of the universe is one of the fundamental goals of cosmology. Detailed measurements of these rates as a function of redshift can provide new physical insights into the nature and…
We investigate the dynamical properties of dark energy through a detailed analysis of its equation of state parameter $w(z)$ as a function of redshift. We derive a general expression for $w(z)$ from the Friedmann-Lema\^itre-Robertson-Walker…
The nature of dark energy is a mystery to us. This paper uses the supernova data to explore the property of dark energy by some model independent methods. We first Talyor expanded the scale factor $a(t)$ to find out the deceleration…
Two new one-parameter tracking behavior dark energy representations $\omega=\omega_0/(1+z)$ and $\omega=\omega_0 e^{z/(1+z)}/(1+z)$ are used to probe the geometry of the Universe and the property of dark energy. The combined type Ia…
Nearly all proposed tests for the nature of dark energy measure some combination of four fundamental observables: the Hubble parameter H(z), the distance-redshift relation d(z), the age-redshift relation t(z), or the linear growth factor…
The model-independent method of using type Ia supernovae proposed and developed by Daly and Djorgovski (2003, 2004) has been applied to the Riess et al. (2007) supernovae sample. Assuming only a Robertson-Walker metric, we find that the…
Bulk dark energy properties are determined by the redshift evolution of its pressure-to-density ratio, $w_{de}(z)$. An experimental goal is to decide if the dark energy is dynamical, as in the quintessence (and phantom) models treated here.…
A huge amount of good quality astrophysical data converges towards the picture of a spatially flat universe undergoing the today observed phase of accelerated expansion. This new observational trend is commonly addressed as Precision…
The expansion rate of the Universe changes with time, initially slowing (decelerating) when the universe was matter dominated, because of the mutual gravitational attraction of all the matter in it, and more recently speeding up…
Early dark energy models, for which the contribution to the dark energy density at high redshifts is not negligible, influence the growth of cosmic structures and could leave observable signatures that are different from the standard…
A phenomenological approach is proposed to the problem of universe accelerated expansion and of the dark energy nature. A general class of models is introduced whose energy density depends on the redshift $z$ in such a way that a smooth…
One of the great endeavors of the past decade has been the evaluation of different observational techniques for measuring dark energy properties and of theoretical techniques for constraining models of cosmic acceleration given cosmological…
We develop a formalism to characterize the redshift evolution of the dark energy potential. Our formalism makes use of quantities similar to the Horizon-flow parameters in inflation and is general enough that can deal with multiscalar…
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…
This review summarizes recent attempts to reconstruct the expansion history of the Universe and to probe the nature of dark energy. Reconstruction methods can be broadly classified into parametric and non-parametric approaches. It is…