Related papers: Supernovae as cosmological probes
Supernovae observations strongly support the presence of a cosmological constant, but its value, which we will call apparent, is normally determined assuming that the universe can be accurately described by a homogeneous model. Even in the…
The accelerated expansion of the Universe is one of the main discoveries of the past decades, indicating the presence of an unknown component: the dark energy. Evidence of its presence is being gathered by a succession of observational…
We show that future observations of binary neutron star systems with electromagnetic counterparts together with the traditional probes of low- and high-redshift Type Ia supernovae (SNe Ia) can help resolve the Hubble tension. The luminosity…
In this paper, we consider a couple of alternative dark energy models using the total equation of state of the cosmological fluid, $\wt$. These models are fit to the recent type-Ia supernovae data and are compared to previously considered…
Dark energy is one of the mysteries of modern science. It is unlike any known form of matter or energy and has been detected so far only by its gravitational effect of repulsion. Owing to its effects being discernible only at very very…
A six parameter cosmological model, involving a vacuum energy density that is extremely tiny compared to fundamental particle physics scales, describes a large body of increasingly accurate astronomical data. In a first part of this brief…
A mildly inhomogeneous universe with a cosmological constant may look like it contains evolving dark energy. We show that could be the case by modelling the inhomogeneities and their effects in three different ways: as clumped matter…
The cosmic microwave background (CMB) offers a unique window into the early universe, providing insights into cosmological parameters like the Hubble constant. Recent precise measurements of the CMB by experiments like Planck seem to point…
In the standard cosmological framework, the Hubble diagram is interpreted by assuming that the light emitted by standard candles propagates in a spatially homogeneous and isotropic spacetime. However, the light from "point sources"--such as…
The smallness of the cosmological constant is one of the basic problems in particle physics and cosmology. Various attempts have been made to explain this mystery, but no satisfactory solution has been found yet. The appearance of extra…
The Cosmic Defect theory has been confronted with four observational constraints: primordial nuclear species abundances emerging from the big bang nucleosynthesis; large scale structure formation in the universe; cosmic microwave background…
The current observations are usually explained by an accelerating expansion of the present universe. However, with the present quality of the supernovae Ia data, the allowed parameter space is wide enough to accommodate the decelerating…
Assuming that supernovae type Ia (SNe Ia) are standard candles one could use them to test cosmological theories. The Hubble Space Telescope team analyzed 186 SNe Ia (Riess et al. (2004)) to test the standard cosmological model (SC) and…
Constantly accumulating observational data continue to confirm that about 70% of the energy density today consists of dark energy responsible for the accelerated expansion of the Universe. We present recent observational bounds on dark…
We extend our previous analysis of cosmological supernova data (Padmanabhan & Choudhury 2003) to include three recent compilation of data sets. Our analysis ignores systematic effects in the data and concentrates on some key theoretical…
After a short history of the $\Lambda$-term it is explained why the (effective) cosmological constant is expected to obtain contributions from short-distance physics, corresponding to an energy at least as large as the Fermi scale. The…
We predict cosmological constraints for forthcoming surveys using Superluminous Supernovae (SLSNe) as standardisable candles. Due to their high peak luminosity, these events can be observed to high redshift (z~3), opening up new…
The simplest cosmological model ($\Lambda$CDM) is well-known to suffer from the Hubble tension, namely an almost $5 \sigma$ discrepancy between the (model-based) early-time determination of the Hubble constant $H_0$ and its late-time (and…
We are at a specific period of modern cosmology, during which the large increase of the amount of data leads to the idea that the determination of cosmological parameters has been achieved with a rather good precision. There is a large…
The cosmological constant, which was introduced by Einstein a century ago to allow for a static universe, experienced a revival two decades ago under the label dark energy as a parameter to model the observed accelerated expansion of the…