Related papers: Using bright ellipticals as dark energy cosmic clo…
Various methods for age dating globular clusters in ellipticals are presented. We first present spectroscopy of individual globular clusters (feasible with the advent of the 10m-class telescopes), and the measurement of Balmer line indices.…
In this paper, we used standard rulers and standard candles (separately and jointly) to explore five popular dark energy models under assumption of spatial flatness of the Universe. As standard rulers, we used a data set comprising 118…
Observing dark energy dynamics is the most important aspect of the dark energy research. In this paper we perform an analysis of the constraints on the property of dark energy from the current astronomical observations. We pay particular…
Observations of high redshift supernovae indicate that the universe is accelerating. The hypothesis of `Dark energy' (cosmological constant, scalar field tracker potentials, braneworld models, etc.) has been advanced to explain this…
Galaxy cluster gas mass fraction versus redshift data and Hubble parameter versus redshift data are used to jointly constrain dark energy models. These constraints favor the Einstein cosmological constant limit of dark energy but do not…
In this paper we probe five cosmological models for which the dark energy equation of state parameter, $w(z)$, is parameterized as a function of redshift using strong lensing data in the galaxy cluster Abell 1689. We constrain the…
We propose to use relative galaxy ages as a means of constraining cosmological parameters. By measuring the age difference between two ensembles of old galaxies at somewhat different redshifts, one could determine the derivative of redshift…
We discuss how future cluster surveys can constrain cosmological parameters with particular reference to the properties of the dark energy component responsible for the observed acceleration of the universe by probing the evolution of the…
(Abridged) We present new theoretical predictions for surface brightness fluctuations (SBFs) using models optimized for this purpose. Our predictions agree well with SBF data for globular clusters and elliptical galaxies. We provide refined…
We propose to use alternative cosmic tracers to measure the dark energy equation of state and the matter content of the Universe [w(z) & Omega_m]. Our proposed method consists of two components: (a) tracing the Hubble relation using HII…
Clusters of galaxies are important laboratories for understanding both galaxy evolution and constraining cosmological quantities. Any analysis of clusters, however, is best done when one can reliably determine which galaxies are members of…
The understanding of the accelerated expansion of the Universe poses one of the most fundamental questions in physics and cosmology today. Whether or not the acceleration is driven by some form of dark energy, and in the absence of a…
In this paper we address the question whether age and metallicity effects can be disentangled with the aid of the broad-band colours and spectral indices from absorption feature strengths, so that the age of elliptical galaxies can be…
We present ACS, NICMOS, and Keck AO-assisted photometry of 20 Type Ia supernovae SNe Ia from the HST Cluster Supernova Survey. The SNe Ia were discovered over the redshift interval 0.623 < z < 1.415. Fourteen of these SNe Ia pass our strict…
The spatial distributions of the mean luminosity-weighted stellar age, metallicity, and alpha/Fe ratio along both photometric axes of two nearby elliptical galaxies have been obtained using Lick index measurements on long slit spectra in…
Spectra of galaxies contain an enormous amount of information about the relative mixture of ages and metallicities of constituent stars. We present a comprehensive study designed to extract the maximum information from spectra of data…
The recent observational evidence for the current cosmic acceleration have stimulated renewed interest in alternative cosmologies, such as scenarios with interaction in the dark sector (dark matter and dark energy). In general, such models…
We determine relative stellar ages and metallicities mainly for about 80 elliptical galaxies in low and high density environments via the latest binary stellar population (BSP) synthesis model and test a latest hierarchical formation model…
We use the HII galaxies $L - \sigma$ relation and the resulting Hubble expansion cosmological probe of a sample of just 25 high-$z$ (up to $z \sim 2.33$) HII galaxies, in a joint likelihood analysis with other well tested cosmological…
Using new narrowband color observations of early-type galaxies in clusters, we reconstruct the color-magnitude relation (CMR) with a higher degree of accuracy than previous work. We then use the spectroscopically determined ages and…