Results 61 to 70 of about 193,127 (291)

What is there in the black box of dark energy: variable cosmological parameters or multiple (interacting) components? [PDF]

, 2007
The coincidence problems and other dynamical features of dark energy are studied in cosmological models with variable cosmological parameters and in models with the composite dark energy.
Bauer F, Copeland E J Sami M Tsujikawa S, Grande J, Grande J Solà J Štefančić H, H Štefančić, J Grande, J Solà, Nojiri S Odintsov S, Sahni V, Shapiro I L, Shapiro I L, Solà J, Spergel D N   +12 more
core   +2 more sources

The THESEUS Space Mission and the Infrared Telescope Calibration Unit

Astronomische Nachrichten, EarlyView.
ABSTRACT The Transient High‐Energy Sky and Early Universe Surveyor (THESEUS) is an ESA M7 mission concept currently in Phase A, designed to exploit gamma‐ray bursts to probe the early Universe while advancing multi‐messenger and time‐domain astrophysics. To achieve its ambitious goals, THESEUS will combine wide‐band x‐ray and gamma‐ray monitors with an
András Péter Joó, Rebeka Gyöngyi Kiss, Lorenzo Amati, Bendegúz Koncz, Örs Detre, Gyula Zilizi, Zsolt Bagoly, István I. Rácz, Sándor Pintér, L. Viktor Tóth   +9 more
wiley   +1 more source

Building analytical three-field cosmological models

European Physical Journal C: Particles and Fields, 2018
A difficult task to deal with is the analytical treatment of models composed of three real scalar fields, as their equations of motion are in general coupled and hard to integrate. In order to overcome this problem we introduce a methodology to construct
J. R. L. Santos, P. H. R. S. Moraes, D. A. Ferreira, D. C. Vilar Neta   +3 more
doaj   +1 more source

Irreversible Processes in Inflationary Cosmological Models [PDF]

, 2002
By using the thermodynamic theory of irreversible processes and Einstein general relativity, a cosmological model is proposed where the early universe is considered as a mixture of a scalar field with a matter field.
A. Albrecht, A. Berera, A. Di Prisco, A.A. Coley, A.H. Guth, A.P. Billyard, B. Ratra, F. P. Devecchi, G. M. Kremer, G.L. Murphy, G.M. Kremer, I. Prigogine, J. Yokoyama, J. Yokoyama, R.J. van den Hoogen, V. Romano, V.A. Belinskiǐ, W. Zimdahl, W. Zimdahl, Ø. Grøn   +19 more
core   +2 more sources

Feasibility Study for Application of Digitized Henize Mt. Wilson Michigan Southern Sky Hα$$ \boldsymbol{\alpha} $$ Survey Low‐Dispersive Spectral Plates for Searches for Anomalous and Highly Redshifted Objects

Astronomische Nachrichten, EarlyView.
ABSTRACT The goal of this study is to confirm the feasibility of the use of digitized low dispersive MtWilson Michigan Southern Sky Hα$$ \alpha $$ survey astronomical photographic plates for modern astrophysical research. The detection of highly redshifted objects, such as early galaxies and quasars, is fundamental to understanding the universe's ...
Tauseef Ahmad Zafar, René Hudec, Marta Mara Merono Vidagany, Fehmi Mejri   +3 more
wiley   +1 more source

Using entropy bounds to avoid the cosmological singularity and constrain cosmological particle production

European Physical Journal C: Particles and Fields, 2023
In this work, we study the applications of entropy bounds in two toy cosmological models with particle production (annihilation), i.e., a radiation-dominated universe and a dust-dominated universe.
Hao Yu, Jin Li
doaj   +1 more source

Cosmological models with flat spatial geometry [PDF]

, 2000
The imposition of symmetries or special geometric properties on submanifolds is less restrictive than to impose them in the full space-time. Starting from this idea, in this paper we study irrotational dust cosmological models in which the geometry of ...
Bonnor W B, Carlos F Sopuerta, Collins C B, Collins C B, Collins C B, Ehlers J, Einstein A, Ellis G F R, Ellis G F R, Hawking S W, Krasinski A, Maartens R, Mars M, Robinson B B, Sopuerta C F, Stephani H, Szafron D A, Szafron D A, Szekeres P, van Elst H, Weinberg S   +20 more
core   +2 more sources

Generating Gowdy cosmological models [PDF]

Journal of Mathematical Physics, 2004
Using the analogy with stationary axisymmetric solutions, we present a method to generate new analytic cosmological solutions of Einstein’s equation belonging to the class of T3 Gowdy cosmological models. We show that the solutions can be generated from their data at the initial singularity and present the formal general solution for arbitrary initial ...
Sanchez, A, Macias, A, Quevedo, Hernando
openaire   +3 more sources

State‐Level Politics in Forest Governance: The Role of the Narrative‐Policy Nexus in the Brazilian Amazon

Environmental Policy and Governance, EarlyView.
ABSTRACT Deforestation and its social impacts are an enduring challenge in agrarian frontiers, especially in the tropics. Fueled by global demand for commodities, this process is mediated by ideas, concepts, meanings, and policies that uphold socioenvironmental degradation. A key and understudied—arena in which this mediation occurs is the sub‐national
Gabriela Russo Lopes, Fabio de Castro
wiley   +1 more source

On the Asymptotic Behaviour of Cosmological Models in Scalar-Tensor Theories of Gravity

, 1998
We study the qualitative properties of cosmological models in scalar-tensor theories of gravity by exploiting the formal equivalence of these theories with general relativity minimally coupled to a scalar field under a conformal transformation and field ...
A. A. Coley, A. Abramovici, A. B. Burd, A. Feinstein, A. Feinstein, A. R. Liddle, A. Serna, Alan Coley, Andrew Billyard, C. Bradaschia, C. Brans, C. G. Hewitt, C. Santos, D. F. Torres, D. Kramer, G. T. Horowitz, J. D. Barrow, J. D. Barrow, J. D. Barrow, J. D. Barrow, J. D. Barrow, J. Hough, J. Ibáñez, J. Ibáñez, J. J. Halliwell, J. M. Aguirregabiria, J. P. Mimoso, Jesus Ibáñez, K. Nordtvedt, K. Nordtvedt, M. Fierz, M. Heusler, P. Chauvet, P. G. Bergmann, P. Jordan, P. Jordan, R. J. van den Hoogen, R. M. Wald, R. V. Wagoner, S. Buchmann, S. Kolitch, Y. Kitada   +41 more
core   +1 more source