Results 11 to 20 of about 92,572 (312)

Observational constraints on Rastall's cosmology [PDF]

The European Physical Journal C, 2013
Rastall's theory is a modification of General Relativity, based on the non-conservation of the stress-energy tensor. The latter is encoded in a parameter $\gamma$ such that $\gamma = 1$ restores the usual $\nabla_\nu T^{\mu\nu} = 0$ law.
A. Felice De, A. M. Velasquez-Toribio, A.G. Riess, A.Y. Kamenshchik, C. E. M. Batista, C.-P. Ma, C.E.M. Batista, D. Bertacca, G. Bertone, J.C. Fabris, J.C. Fabris, J.C. Fabris, J.C. Fabris, Júlio C. Fabris, M. Capone, M. Hicken, M. Li, M.H. Daouda, N.D. Birrell, O.F. Piattella, O.F. Piattella, O.F. Piattella, Oliver F. Piattella, P. Rastall, P. Rastall, R. Colistete, R.R. Caldwell, T. Clifton, V. Gorini, W. Zimdahl, W. Zimdahl, W. Zimdahl, W.S. Hipolito-Ricaldi   +32 more
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Observational Cosmology in Macroscopic Gravity [PDF]

Journal of Cosmology and Astroparticle Physics, 2012
We discuss the construction of cosmological models within the framework of Macroscopic Gravity (MG), which is a theory that models the effects of averaging the geometry of space-time on large scales.
Alan Coley, D.L. Wiltshire, D.L. Wiltshire, G.F.R. Ellis, K. Bolejko, R.J. van den Hoogen, R.M. Zalaletdinov, R.M. Zalaletdinov, Robert van den Hoogen, See special focus section in CQG on inhomogeneous cosmological models, T. Buchert, Timothy Clifton   +11 more
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Observations in quantum cosmology

Classical and Quantum Gravity, 2023
Abstract In this review, we focus on whether a canonical quantization of general relativity can produce testable predictions for cosmology. In particular, we examine how this approach can be used to model the evolution of primordial perturbations. This program of quantum geometrodynamics, first advocated by John Wheeler and Bryce DeWitt,
Leonardo Chataignier, Claus Kiefer, Paulo Moniz   +2 more
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Space and observers in cosmology [PDF]

Astronomy & Astrophysics, 2001
I provide a prescription to define space, at a given moment, for an arbitrary observer in an arbitrary (sufficiently regular) curved space-time. This prescription, based on synchronicity (simultaneity) arguments, defines a foliation of space-time, which corresponds to a family of canonically associated observers.
openaire   +2 more sources

Observational constraints on soft dark energy and soft dark matter: Challenging ΛCDM cosmology

Nuclear Physics B, 2023
Soft cosmology is an extension of standard cosmology allowing for a scale-dependent equation-of-state (EoS) parameter in the dark sectors, which is one of the properties of soft materials in condensed-matter physics, that may arise either intrinsically ...
Emmanuel N. Saridakis, Weiqiang Yang, Supriya Pan, Fotios K. Anagnostopoulos, Spyros Basilakos   +4 more
doaj   +1 more source

Machine learning for observational cosmology

Reports on Progress in Physics, 2023
Abstract An array of large observational programs using ground-based and space-borne telescopes is planned in the next decade. The forthcoming wide-field sky surveys are expected to deliver a sheer volume of data exceeding an exabyte.
Kana Moriwaki, Takahiro Nishimichi, Naoki Yoshida   +2 more
openaire   +3 more sources

The current status of observational cosmology [PDF]

, 2004
Observational cosmology has indeed made very rapid progress in recent years. The ability to quantify the universe has largely improved due to observational constraints coming from structure formation.
A A Starobinsky, A C Pope, A G Reiss, A H Guth, A Hajian, A Kogut, A Niarchou, A Shafieloo, C J Copi, C L Bennett, C Lacey, C Park, C R Contaldi, D Kirkman, D Munshi, D N Spergel, D N Spergel, D N Spergel, E Komatsu, G F Smoot, H K Eriksen, H K Eriksen, J L Tonry, J M Bardeen, J M Kovac, J P Ostriker, J R Bond, Jeremiah P. Ostriker, M Kaplinghat, M Tegmark, M Tegmark, N Bahcall, P Bode, P Colin, P J E Peebles, R H Cyburt, RAC Croft, T Padmanabhan, Tarun Souradeep, V Sahni, W Hu, W J Percival, W L Freedman   +42 more
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Average observational quantities in the timescape cosmology [PDF]

, 2009
We examine the properties of a recently proposed observationally viable alternative to homogeneous cosmology with smooth dark energy, the timescape cosmology.
A. Gabrielli, A. Shafieloo, D. L. Wiltshire, David L. Wiltshire, G. C. McVittie, G. F. R. Ellis, M. N. Célérier, M. N. Célérier, S. Räsänen, T. Buchert   +9 more
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Observational Cosmology [PDF]

Proceedings of European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2019), 2020
Despite the title, I am afraid that I will not be able to really do justice to the broad topic I was given to review. But I will show the current striking level of precise consistency between the CMB and LSS data \textit{within the \LCDM\ theoretical framework} (with the acronyms CMB and LSS standing for Cosmic Microwave Background and Large Scale ...
openaire   +2 more sources

Highly Accreting Supermassive Black Holes as Eddington Standard Candles

Physical Sciences Forum, 2023
Supermassive black holes accreting matter at very high, perhaps even super-Eddington rates appear in the sky as a special class of luminous active galactic nuclei.
Paola Marziani
doaj   +1 more source