Conveners
Dark energy and the accelerating universe: Thursday block 1
- David Polarski (Université de Montpellier)
- Arman Shafieloo (Korea Astronomy and Space Science Institute)
Dark energy and the accelerating universe: Thursday block 2
- Arman Shafieloo (Korea Astronomy and Space Science Institute)
- David Polarski (Université de Montpellier)
Description
This parallel session will be devoted to the study of the nature and the physical properties of Dark Energy producing the observed accelerated expansion of the present Universe. It will cover the phenomenological reconstruction of dark energy properties from observations, as well as consideration of a wide variety of theoretical models and approaches aimed to explain existing observational data, including modified gravity models, interacting dark energy and other extensions.
What has everyone so excited about the H0 tension is the potential for discovering new physics, such as the physics of dark energy. In particular, the question of new physics explanations for this tension are often divided into whether the new physics plays a role at high redshift or low redshift. In this talk, I will make the case that there can be no low-redshift solution to the H0 tension....
In this talk, I will review the state of the art of dark energy in light of the early Stage IV surveys results.
In this work, we construct the Raychaudhuri equation in $f(\bar{R},\bar{T})$ gravity in the context of a non-canonical theory, which is the K-essence theory. We solved the modified Raychaudhuri equation for the additive form of $f(\bar{R},\bar{T})$, which is $f_{1}(\bar{R})+f_{2}(\bar{T})$. In this solution, we use two distinct scale factors to generate two kinds of $f(\bar{R},\bar{T})$...
As a potential candidate for the late-time accelerating expansion of the Universe, the Chaplygin gas and its generalized models have significant implications to modern cosmology. In this study we explore the effects of dark energy on the internal structure of a neutron star composed of two phases, which leads us to wonder: Do stable neutron stars have a dark-energy core? To address this...
There is no doubt that we live in a Gravitational Wave Background (GWB). In this talk we start from this hypothesis and show that if we take into account the energy generated by the GWB we have to extend Einstein's equations with a term $2\pi^2/\lambda^2$, where $\lambda$ is the Compton wave length of the graviton of the size of the observable universe. We call this model Compton Mass Dark...
In some modern theories, fields of the Standard Model of particle physics are allowed to interact with dark matter and dark energy. Such interactions, if they exist, may give rise to temporal evolution of the fine structure constant ($\alpha$) or its spatial variations. Consequently, stringent constraints on such theories can be placed by searching for any possible $\alpha$ variation. Recent...
Cosmic voids, large under-dense regions in the Universe, serve as promising laboratories for extracting cosmological information. They offer opportunities to explore deviations from $\Lambda CDM$ and provide insights into dark energy and modification of gravity. Upcoming surveys like Euclid will enable detailed void analyses, allowing access to a huge number of voids. Voids' significance lies...
A cosmological model with a new variant of Chaplygin gas obeying an equation of state(EoS), $p=-\frac{B}{ρ^α}$ where $B=B_0 a^n$[1], is investigated in the context of its thermodynamical behaviour. Here $B_0$ and $n$ are constants and $a$ is scale factor. We show that the equation of state of this ‘Variable Chaplygin gas’ (VGCG) can describe the current accelerated expansion of the...
The luminosity distance-redshift ($D_L$-$z$) relation of Type Ia supernovae (SNe Ia) yields evidence for a nonzero cosmological constant, i.e. `dark energy'. SNe Ia analyses typically involve fitting the $D_L$ and $z$ to the functional form derived theoretically from the homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker (FLRW) metric. However, the metric in the epoch relevant to...
I will introduce a dynamical system formulation for inhomogeneous LRS-II spacetimes using the covariant 1+1+2 decomposition approach, that we recently proposed in 2404.01161. Our approach describes the LRS-II dynamics from the point of view of a comoving observer. Promoting the covariant radial derivatives of the covariant dynamical quantities to new dynamical variables and utilizing the...
