Related papers: Dark Energy: A Short Review
The traditional "explanation" for the observed acceleration of the universe is the existence of a positive cosmological constant. However, this can hardly be a truly convincing explanation, as an expanding universe is not expected to have a…
One of the greatest challenges in cosmology today is to determine the nature of dark energy, the source of the observed present acceleration of the universe. High precision experiments are being developed to reduce the uncertainties in the…
Nonlocal massive gravity can provide an interesting explanation for the late-time cosmic acceleration, with a dark energy equation of state $w_{\rm DE}$ smaller than $-1$ in the past. We derive the equations of linear cosmological…
The discovery of the accelerating universe in the late 1990s was a watershed moment in modern cosmology, as it indicated the presence of a fundamentally new, dominant contribution to the energy budget of the universe. Evidence for dark…
Cosmological parameters are constrained by a wide variety of observations. We examine the concordance diagram for modern measurements of the Hubble constant, the shape parameter from large scale structure, the cluster baryon fraction, and…
Based on dramatic observations of the CMB with WMAP and of Type Ia supernovae with the Hubble Space Telescope and ground-based facilities, it is now generally believed that the Universe's expansion is accelerating. Within the context of…
One of the biggest mysteries in cosmology is Dark Energy, which is required to explain the accelerated expansion of the universe within the standard model. But maybe one can explain the observations without introducing new physics, by…
The nature of dark matter is one of the most fundamental questions in cosmology. Using the cosmic microwave background (CMB), type Ia supernova (SN) and DESI's new measurements of baryon acoustic oscillations (BAO), we find the robust…
In this study, we explore the impact of various combinations of CMB-independent datasets, including the recent DESI BAO measurements, on the equation of state (EoS) of dark energy and other cosmological parameters within the framework of…
The $\Lambda$ cold dark matter ($\Lambda$CDM) cosmological model provides a good description of a wide range of astrophysical and cosmological observations. However, severe challenges to the phenomenological $\Lambda$CDM model have emerged…
Baryon Acoustic Oscillations (BAO) allow us to determine the expansion history of the Universe, thereby shedding light on the nature of dark energy. Recent observations of BAO's in the SDSS DR9 and DR11 have provided us with statistically…
Observations of the cosmic microwave backgroundradiation are described to remarkable accuracy by the six-parameterLambda CDM cosmology. However, the key ingredients of this model, namely dark matter, dark energy and cosmic inflation are not…
The cause for the observed acceleration in the expansion of the universe is unknown, and referred to as "dark energy" for convenience. Dark energy could be an unknown energy component, or a modification of Einstein's general relativity.…
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…
We explore extensions to the $\Lambda$CDM cosmology using measurements of the cosmic microwave background (CMB) from the recent SPT-SZ survey, along with data from WMAP7 and measurements of $H_0$ and BAO. We check for consistency within…
New measurements of the cosmic microwave background (CMB) by the Planck mission have greatly increased our knowledge about the Universe. Dark radiation, a weakly interacting component of radiation, is one of the important ingredients in our…
The Hubble constant ($H_0$), which represents the expansion rate of the Universe, is one of the most important cosmological parameters. The recent measurements of $H_0$ using the distance ladder methods such as Type Ia Supernovae (SNe Ia)…
The discovery of cosmic acceleration has stimulated theorists to consider dark energy or modifications to Einstein's General Relativity as possible explanations. The last decade has seen advances in theories that go beyond smooth dark…
We investigate the course of cosmic expansion in its `recent past' using the Constitution SN Ia sample (which includes CfA data at low redshifts), jointly with signatures of baryon acoustic oscillations (BAO) in the galaxy distribution and…
The possibility of linking inflation and late cosmic accelerated expansion using the $\alpha$-attractor models has received increasing attention due to their physical motivation. In the early universe, $\alpha$-attractors provide an…