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We discuss the present bounds on the relativistic energy density in the Universe parameterized in terms of the effective number of neutrinos N using the most recent cosmological data on Cosmic Microwave Background (CMB) temperature…

Astrophysics · Physics 2010-10-27 Gianpiero Mangano , Alessandro Melchiorri , Olga Mena , Gennaro Miele , Anze Slosar

Current observational bounds on dark energy depend on assumptions about the curvature of the universe. We present a simple and efficient method for incorporating constraints from CMB anisotropy data, and use it to derive constraints on…

Astrophysics · Physics 2010-04-06 Yun Wang , Pia Mukherjee

The Quantum Null Energy Condition (QNEC) is a new local energy condition that a general Quantum Field Theory (QFT) is believed to satisfy, relating the classical null energy condition (NEC) to the second functional derivative of the…

High Energy Physics - Theory · Physics 2018-07-04 Christian Ecker , Daniel Grumiller , Wilke van der Schee , Philipp Stanzer

Reconstructing the expansion history of the Universe from type Ia supernovae data, we fit the growth rate measurements and put model-independent constraints on some key cosmological parameters, namely, $\Omega_\mathrm{m},\gamma$, and…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-10 Benjamin L'Huillier , Arman Shafieloo , Hyungjin Kim

It is a very well known fact that the energy conditions concerning traversable wormhole (WH) solutions of Einstein equations are violated. Consequently, attempts to avoid the violation of the energy conditions constitutes one of the main…

General Relativity and Quantum Cosmology · Physics 2014-04-14 Everton M. C. Abreu , Nélio Sasaki

We give an alternate proof of one of the results given in [16] showing that initial data sets with boundary for the Einstein equations $(M, g, k)$ satisfying the dominant energy condition can be conformally deformed to the strict dominant…

General Relativity and Quantum Cosmology · Physics 2025-07-14 Jaroslaw S. Jaracz

We demonstrate that the constraints on the evolution of dark energy implemented by the DESI collaboration may be insufficient or incomplete using their own BAO data. Using large enough prior ranges for the present-day equation of state of…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-23 Deng Wang

By studying the present cosmological data, particularly on CMB, SNeIA and LSS, we find that the future fate of the universe, for simple linear models of the dark energy equation-of-state, can vary between the extremes of (I) a divergence of…

Astrophysics · Physics 2009-11-10 Paul H. Frampton

Non-negligible dark energy density at high redshifts would indicate dark energy physics distinct from a cosmological constant or ``reasonable'' canonical scalar fields. Such dark energy can be constrained tightly through investigation of…

Astrophysics · Physics 2015-06-24 Eric V. Linder

In this article, we explore the relationship between the existence of closed timelike curves and energy conditions that occur in the Kerr-Newman spacetime. To quantify the dependence, we define a correlation index between energy conditions…

General Relativity and Quantum Cosmology · Physics 2021-08-24 Sashideep Gutti , Shailesh Kulkarni , Vaishak Prasad , Sheldon Suresh

Observations of the synchrotron and inverse Compton emissions from ultrarelativistic electrons in astrophysical sources can reveal a great deal about the energy-momentum relations of those electrons. They can thus be used to place bounds on…

High Energy Physics - Phenomenology · Physics 2021-04-19 Brett Altschul

In this paper we investigate the energy distribution of states of a linear scalar quantum field with arbitrary curvature coupling on a curved spacetime which fulfill some local thermality condition. We find that this condition implies a…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Jan Schlemmer , Rainer Verch

In order to shed some light on the current discussion about f(R)-gravity theories we derive and discuss the bounds imposed by the energy conditions on a general f(R) functional form. The null and strong energy conditions in this framework…

Astrophysics · Physics 2008-11-26 J. Santos , J. S. Alcaniz , M. J. Reboucas , F. C. Carvalho

There has been recent interest in the cosmological consequences of energy-momentum-powered gravity models, in which the matter side of Einstein's equations includes a term proportional to some power, $n$, of the energy-momentum tensor, in…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-03 C. J. A. P. Martins , A. M. M. Vieira

Positivity bounds - the consequences of requiring a unitary, causal, local UV completion - place strong restrictions on theories of dark energy and/or modified gravity. We derive and investigate such bounds for Horndeski scalar-tensor…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-28 Scott Melville , Johannes Noller

We perform a comprehensive study of a class of dark energy models - scalar field models where the effective potential can be described by a polynomial series - exploring their dynamical behavior using the method of flow equations that has…

Astrophysics · Physics 2008-11-26 Dragan Huterer , Hiranya V. Peiris

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…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-13 Manisg Yadav , Archana Dixit , M. S. Barak , Anirudh Pradhan

Cosmological measurements are affected by the energy density of both active and sterile massive neutrinos. We extend here a recent analysis of current cosmological data to non minimal cosmologies. Several possible scenarios are examined: a…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Elena Giusarma , Maria Archidiacono , Roland de Putter , Alessandro Melchiorri , Olga Mena

The dark energy component of the cosmic budget is represented by a self-interacting scalar field. The violation of the null energy condition is allowed. Hence, such component can also represent a phantom fluid. The model is tested using…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Julio C. Fabris , Deborah F. Jardim

We study future constraints on dark energy parameters determined from several combinations of CMB experiments, supernova data, and weak lensing surveys with and without tomography. In this analysis, we look in particular for combinations…

Astrophysics · Physics 2011-02-01 Mustapha Ishak
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