Results 61 to 70 of about 3,462 (164)

Inferring the cosmological constant in early Universe only by gravitational waves

Journal of High Energy Physics
Gravitational waves (GWs) from compact binary coalescence (CBC) can directly determine the luminosity distance but usually can not obtain information about the redshift. This assumes that the GW source is at the flat background.
Song Li, Wen-Biao Han
doaj   +1 more source

Testing the scalar weak gravity conjecture in no-scale supergravity

Journal of High Energy Physics
We explore possible extensions of the Weak Gravity Conjecture (WGC) to scalar field theories. To avoid charged black hole remnants, the WGC requires the existence of a particle with a mass m ≤ gqM P , with charge q and U(1) gauge coupling g, allowing the
Emilian Dudas, Tony Gherghetta, Keith A. Olive, Sarunas Verner   +3 more
doaj   +1 more source

On pre-inflationary non Gaussianities

Journal of High Energy Physics
We explore the three-point amplitude of curvature perturbations in scenarios suggested by high-scale supersymmetry breaking in String Theory, where the inflaton is forced to climb a steep exponential potential.
M. Meo, A. Sagnotti
doaj   +1 more source

Early universe in quantum gravity

Journal of High Energy Physics
We present a new picture of the early universe in finite nonlocal quantum gravity, which is Weyl invariant at the classical and quantum levels. The high-energy regime of the theory consists of two phases, a Weyl invariant trans-Planckian phase and a post-
Leonardo Modesto, Gianluca Calcagni
doaj   +1 more source

The cosmological impact of Brane-Chern-Simons massive gravity

Journal of High Energy Physics
In this paper, we present a novel extension of massive gravity theory; the Brane-Chern-Simons massive gravity theory. We explore the cosmological implications of this theory by deriving the background equations and demonstrating the existence of self ...
S. Kazempour, A. R. Akbarieh
doaj   +1 more source

The Excess of JWST Bright Galaxies: A Possible Origin in the Ground State of Dynamical Dark Energy in the Light of DESI 2024 Data

The Astrophysical Journal
Recent observations by JWST yield a large abundance of luminous galaxies at z ≳ 10 compared to that expected in the ΛCDM scenario based on extrapolations of the star formation efficiency measured at lower redshifts.
N. Menci, A. A. Sen, M. Castellano
doaj   +1 more source

ASYMPTOTIC STRUCTURE OF SIMPLE COSMOLOGICAL MODELS

Anales (Asociación Física Argentina), 2013
The future null infinity for all non-contracting Robertson-Walker spacetimes is studied systematically. A theorem is proved which establishes the expected relation between the nature of g + and the appearance or absence of cosmic event horizons.
O. Moreschi
doaj  

Is Dark Energy Changing? Probing the Universe’s Expansion with Present and Future Astronomical Probes

The Astrophysical Journal
This study explores the possibility of a time-varying dark energy (DE) equation of state (EoS) deviating from −1. We employ a comprehensive data set of the usual astronomical probes (Type Ia supernovae, baryon acoustic oscillations, Big Bang ...
Mehdi Rezaei, Supriya Pan, Weiqiang Yang, David F. Mota   +3 more
doaj   +1 more source

Beyond Two Parameters: Revisiting Dark Energy with the Latest Cosmic Probes

The Astrophysical Journal
Dark energy (DE) models with many free parameters are often considered excessive, as constraining all parameters poses a significant challenge. While such models offer greater flexibility to probe the DE sector in more detail.
Hanyu Cheng, Supriya Pan, Eleonora Di Valentino   +2 more
doaj   +1 more source

Spherical cosmological models: an alternative cosmology

, 2018
The properties of universes are explored that are entirely in the interior of black holes in another universe, a `mother universe'. It is argued that these models offer a paradigm that may shed a new light on old cosmological problems. The geometry of such a universe is discussed including how it would appear to the observer.
openaire   +2 more sources