Related papers: The cosmological parameters from supernovae
In the late 1990's, observations of 93 Type Ia supernovae were analysed in the framework of the FLRW cosmology assuming these to be `standard(isable) candles'. It was thus inferred that the Hubble expansion rate is accelerating as if driven…
As revealed by Hubble in 1928, our Universe is expanding. This discovery was fundamental to widening our horizons and our conception of space, and since then determining the rate at which our Universe is expanding has become one of the…
We put forward a pressure-parametric model to study the tiny deviation from cosmological constant(CC) behavior of the dark sector accelerating the expansion of the Universe. Data from cosmic microwave background (CMB) anisotropies, baryonic…
The following review presents an attempt to discuss various issues of current interest in Observational Cosmology, the selection of which as well as the emphasis given, reflects my own preference and biases. After presenting some…
Currently, the $\Lambda$ Cold Dark Matter model, which relies on the existence of cold dark matter and a cosmological constant $\Lambda$, best describes the Universe. However, we lack information in the high-redshift ($z$) region between…
It is pointed out that very recent results based on supernovae observations that the universe will accelerate and expand for ever with ever decreasing density have been predicted in a recent cosmological model which also deduces hitherto…
The results of different analyses of the dynamical parameters of the Universe are converging towards agreement. Remaining disagreements reflect systematic errors coming either from the observations or from differences in the methods of…
We discuss recent evidence for an accelerating Universe from measurements of type Ia supernovae at high redshift, and describe tests of various systematic effects such as extinction and evolution that could be biasing the cosmological…
The standard concordance model of the Universe is based on the cosmological constant as the driver of accelerating expansion. This concordance model is being subjected to a growing range of inter-locking observations. In addition to using…
This is a personal review of various issues related to massive photometric and astrometric searches. A complete inventory of variable stars down to almost any magnitude limit will improve our understanding of the stellar evolution and the…
We consider ever-expanding Big Bang models with a cosmological constant, $\Lambda$, and investigate in detail the evolution of the observable part of the universe. We also discuss quintessence models from the same point of view. A new…
The Standard Cosmological Model has experienced tremendous success at reproducing observational data by assuming a universe dominated by a cosmological constant and dark matter in a flat geometry. However, several studies, based on local…
By relaxing the constraint of adiabatic universe used in most cosmological models, we have shown that the new approach provides a better fit to the supernovae Ia redshift data with a single parameter, the Hubble constant $H_0$, than the…
Based on the assumption that some apparent properties of the observable universe are accurate at a reasonable level of approximation, a tentative is made to independently derive the values of the baryon density parameter, the Hubble…
Given a class of dark energy models, constraints from one set of cosmic acceleration observables make predictions for other observables. Here we present the allowed ranges for the expansion rate H(z), distances D(z), and the linear growth…
We use observational data on the large scale structure (LSS) of the Universe measured over a wide range of scales from sub-galactic up to horizon scale and on the cosmic microwave background anisotropies to determine cosmological parameters…
Given the persistence of various tensions in the "Cosmic Concordance" -- such as the "Hubble Tension", and possible departures from LambdaCDM time evolution -- seen from combinations of complementary data sets (e.g., Cosmic Microwave…
Neutron stars are the densest, directly observable stellar objects in the universe and serve as unique astrophysical laboratories to study the behavior of matter under extreme physical conditions. This book chapter is devoted to describing…
Redshifts used in current cosmological supernova samples are measured using two primary techniques, one based on well-measured host galaxy spectral lines and the other based on supernova-dominated spectra. Here, we construct an updated…
Mapping the expansion of the universe gives clues to the underlying physics causing the recently discovered acceleration of the expansion, and enables discrimination among cosmological models. We examine the utility of measuring the rate of…