Galileon as a local modification of gravity
TLDR
In this article, the authors study the connection between self-acceleration and the presence of ghosts for a quite generic class of theories that modify gravity in the infrared, defined as those that at distances shorter than cosmological, reduce to a certain generalization of the Dvali-Gabadadze-Porrati (DGP) effective theory.Abstract:
In the Dvali-Gabadadze-Porrati (DGP) model, the "self-accelerating" solution is plagued by a ghost instability, which makes the solution untenable. This fact, as well as all interesting departures from general relativity (GR), are fully captured by a four-dimensional effective Lagrangian, valid at distances smaller than the present Hubble scale. The 4D effective theory involves a relativistic scalar pi, universally coupled to matter and with peculiar derivative self-interactions. In this paper, we study the connection between self-acceleration and the presence of ghosts for a quite generic class of theories that modify gravity in the infrared. These theories are defined as those that at distances shorter than cosmological, reduce to a certain generalization of the DGP 4D effective theory. We argue that for infrared modifications of GR locally due to a universally coupled scalar, our generalization is the only one that allows for a robust implementation of the Vainshtein effect-the decoupling of the scalar from matter in gravitationally bound systems-necessary to recover agreement with solar-system tests. Our generalization involves an internal Galilean invariance, under which pi's gradient shifts by a constant. This symmetry constrains the structure of the pi Lagrangian so much so that in 4D there exist only five terms that can yield sizable nonlinearities without introducing ghosts. We show that for such theories in fact there are "self-accelerating" de Sitter solutions with no ghostlike instabilities. In the presence of compact sources, these solutions can support spherically symmetric, Vainshtein-like nonlinear perturbations that are also stable against small fluctuations. We investigate a possible infrared completion of these theories at scales of order of the Hubble horizon, and larger. There are however some features of our theories that may constitute a problem at the theoretical or phenomenological level: the presence of superluminal excitations; the extreme subluminality of other excitations, which makes the quasistatic approximation for certain solar-system observables unreliable due to Cherenkov emission; the very low strong-interaction scale for pi pi scatterings.read more
Citations
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Modified Gravity and Cosmology
TL;DR: A comprehensive survey of recent work on modified theories of gravity and their cosmological consequences can be found in this article, where the authors provide a reference tool for researchers and students in cosmology and gravitational physics, as well as a selfcontained, comprehensive and up-to-date introduction to the subject as a whole.
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Planck 2015 results. XX. Constraints on inflation
Peter A. R. Ade,Nabila Aghanim,Monique Arnaud,Frederico Arroja,M. Ashdown,J. Aumont,Carlo Baccigalupi,Mario Ballardini,A. J. Banday,R. B. Barreiro,Nicola Bartolo,E. Battaner,K. Benabed,Alain Benoit,A. Benoit-Lévy,J.-P. Bernard,Marco Bersanelli,P. Bielewicz,J. J. Bock,Anna Bonaldi,Laura Bonavera,J. R. Bond,Julian Borrill,François R. Bouchet,F. Boulanger,M. Bucher,Carlo Burigana,R. C. Butler,Erminia Calabrese,Jean-François Cardoso,A. Catalano,Anthony Challinor,A. Chamballu,R.-R. Chary,H. C. Chiang,P. R. Christensen,Sarah E. Church,David L. Clements,S. Colombi,L. P. L. Colombo,C. Combet,D. Contreras,F. Couchot,A. Coulais,B. P. Crill,A. Curto,F. Cuttaia,Luigi Danese,R. D. Davies,R. J. Davis,P. de Bernardis,A. de Rosa,G. de Zotti,Jacques Delabrouille,F.-X. Désert,Jose M. Diego,H. Dole,S. Donzelli,Olivier Doré,Marian Douspis,A. Ducout,X. Dupac,George Efstathiou,F. Elsner,Torsten A. Ensslin,H. K. Eriksen,James R. Fergusson,Fabio Finelli,Olivier Forni,M. Frailis,Aurelien A. Fraisse,E. Franceschi,A. Frejsel,Andrei V. Frolov,S. Galeotta,Silvia Galli,K. Ganga,C. Gauthier,M. Giard,Y. Giraud-Héraud,E. Gjerløw,J. González-Nuevo,Krzysztof M. Gorski,Serge Gratton,A. Gregorio,Alessandro Gruppuso,Jon E. Gudmundsson,Jan Hamann,Will Handley,F. K. Hansen,Duncan Hanson,D. L. Harrison,Sophie Henrot-Versille,C. Hernández-Monteagudo,D. Herranz,S. R. Hildebrandt,E. Hivon,Michael P. Hobson,W. A. Holmes +98 more
TL;DR: In this article, the authors report on the implications for cosmic inflation of the 2018 Release of the Planck CMB anisotropy measurements, which are fully consistent with the two previous Planck cosmological releases, but have smaller uncertainties thanks to improvements in the characterization of polarization at low and high multipoles.
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f(R) theories
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Dark energy cosmology: the equivalent description via different theoretical models and cosmography tests
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Dark energy cosmology: the equivalent description via different theoretical models and cosmography tests
TL;DR: In this article, a review of different dark energy cosmologies is presented, including the Lambda$CDM cosmology, Little Rip and Pseudo-Rip universes, the phantom and quintessence cosmology with Type I, II, III and IV finite-time future singularities and non-singular dark energy universes.
References
More filters
Journal ArticleDOI
Measurements of Omega and Lambda from 42 High-Redshift Supernovae
Saul Perlmutter,Saul Perlmutter,Greg Aldering,Gerson Goldhaber,Gerson Goldhaber,R. A. Knop,Peter Nugent,P. G. Castro,P. G. Castro,Susana E. Deustua,Sebastien Fabbro,Sebastien Fabbro,A. Goobar,A. Goobar,Donald E. Groom,I. M. Hook,I. M. Hook,A. G. Kim,A. G. Kim,A. G. Kim,M. Y. Kim,Julia C. Lee,Julia C. Lee,Nelson J. Nunes,Nelson J. Nunes,Reynald Pain,Reynald Pain,C. R. Pennypacker,C. R. Pennypacker,Robert Quimby,Christopher Lidman,Richard S. Ellis,Mike Irwin,Richard G. McMahon,Pilar Ruiz-Lapuente,Nicholas A. Walton,Bradley E. Schaefer,B. J. Boyle,Alexei V. Filippenko,Thomas Matheson,A. S. Fruchter,Nino Panagia,Nino Panagia,Heidi Jo Newberg,Warrick J. Couch +44 more
TL;DR: In this paper, the mass density, Omega_M, and cosmological-constant energy density of the universe were measured using the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology project.
Journal ArticleDOI
Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
Adam G. Riess,Alexei V. Filippenko,Peter Challis,Alejandro Clocchiatti,Alan H. Diercks,Peter M. Garnavich,R. L. Gilliland,Craig J. Hogan,Saurabh Jha,Robert P. Kirshner,Bruno Leibundgut,Mark M. Phillips,David J Reiss,Brian P. Schmidt,R. A. Schommer,R. Chris Smith,R. Chris Smith,Jason Spyromilio,Christopher W. Stubbs,Nicholas B. Suntzeff,John L. Tonry +20 more
TL;DR: In this article, the authors used spectral and photometric observations of 10 Type Ia supernovae (SNe Ia) in the redshift range 0.16 " z " 0.62.
Journal ArticleDOI
Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
Adam G. Riess,Alexei V. Filippenko,Peter Challis,Alejandro Clocchiattia,Alan H. Diercks,Peter M. Garnavich,R. L. Gilliland,Craig J. Hogan,Saurabh Jha,Robert P. Kirshner,Bruno Leibundgut,Mark M. Phillips,David J Reiss,Brian P. Schmidt,Robert A. Schommer,R. Chris Smith,Jason Spyromilio,Christopher W. Stubbs,Nicholas B. Suntzeff,John L. Tonry +19 more
TL;DR: In this paper, the authors present observations of 10 type Ia supernovae (SNe Ia) between 0.16 0 and 4.0 sigma confidence levels, for two fitting methods respectively.
Journal ArticleDOI
Measurements of Omega and Lambda from 42 High-Redshift Supernovae
Saul Perlmutter,Greg Aldering,G. Goldhaber,R. A. Knop,Peter Nugent,P. G. Castro,Susana E. Deustua,Sebastien Fabbro,A. Goobar,D. E. Groom,I. M. Hook,A. G. Kim,M. Y. Kim,Julia C. Lee,Nelson J. Nunes,Reynald Pain,C. R. Pennypacker,R. M. Quimby,C. Lidman,Richard S. Ellis,Michael G. Irwin,Richard G. McMahon,P. Ruiz-Lapuente,Nicholas A. Walton,Bradley E. Schaefer,B. J. Boyle,Alexei V. Filippenko,Thomas Matheson,A. S. Fruchter,Nino Panagia,Heidi Jo Newberg,W. J. Couch +31 more
TL;DR: In this paper, the mass density, Omega_M, and cosmological-constant energy density of the universe were measured by the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology Project.
Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant To Appear in the Astronomical Journal
Adam G. Riess,Alexei V. Filippenko,Peter Challis,A. Clocchiatti,Alan H. Diercks,R. L. Gilliland,Craig J. Hogan,Saurabh Jha,Robert P. Kirshner,Bruno Leibundgut,David J Reiss,Brian P. Schmidt,Robert A. Schommer,R. Chris Smith,Jason Spyromilio,Christopher W. Stubbs,Nicholas B. Suntzeff,John L. Tonry +17 more
TL;DR: The spectral and photometric observations of 10 type Ia supernovae (SNe Ia) in the redshift range 0.16 � z � 0.62 were presented in this paper.
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