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Casas R.,Institute Of Ciencies Of Lespai Ieec Csic | Vaquero J.M.,University of Extremadura
Solar Physics | Year: 2014

In the 19th century, several astronomers made observations of sunspots, recording their positions and sometimes their areas. These observations were published in the form of extensive tables, but have been unhelpful until now. Three of these observers were Richard C. Carrington, Christian H.F. Peters and Warren de la Rue (and their respective collaborators). They published, in various articles, the data corresponding to 26 641 sunspot positions (Carrington, Peters and de la Rue registered 4900, 14040 and 7701 sunspot positions, respectively). In this paper we present a translation of more than 400 pages of their printed numerical tables into a machine readable format, including an initial analysis targeted at detecting possible mistakes in the reading or in the original transcription. The observations carried out by these three astronomers have been made available at the Centre de Donées Astronomiques de Strasbourg (http://cdsarc.u-strasbg.fr/cgi-bin/VizieR?-source=VI/138). © 2013 Springer Science+Business Media Dordrecht.

Odintsov S.D.,Institute Of Ciencies Of Lespai Ieec Csic | Odintsov S.D.,Tomsk State Pedagogical University | Oikonomou V.K.,Aristotle University of Thessaloniki | Oikonomou V.K.,Tomsk State Pedagogical University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We investigate which Jordan frame F(R) gravity can describe a type IV singular bouncing cosmological evolution, with special emphasis given near the point at which the type IV singularity occurs. The cosmological bounce is chosen in such a way that the bouncing point coincides exactly with the type IV singularity point. The stability of the resulting F(R) gravity is examined and in addition, we study the Einstein frame scalar-tensor theory counterpart of the resulting Jordan frame F(R) gravity. Also, by assuming that the Jordan frame metric is chosen in such a way so that, when conformally transformed in the Einstein frame, it yields a quasi-de Sitter or de Sitter-Friedmann-Robertson-Walker metric, we study the observational indexes which turn out to be consistent with Planck 2015 data in the case of the Einstein frame scalar theory. Finally, we study the behavior of the effective equation of state corresponding to the type IV singular bounce and after we compare the resulting picture with other bouncing cosmologies, we critically discuss the implications of our analysis. © 2015 American Physical Society.

Kluson J.,Masaryk University | Nojiri S.,Nagoya University | Odintsov S.D.,Catalan Institution for Research and Advanced Studies | Odintsov S.D.,Institute Of Ciencies Of Lespai Ieec Csic | Odintsov S.D.,Tomsk State Pedagogical University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We propose new version of massive F(R) gravity which is natural generalization of convenient massive ghost-free gravity. Its Hamiltonian formulation in scalar-tensor frame is developed. We show that such F(R) theory is ghost-free. The cosmological evolution of such theory is investigated. Despite the strong Bianchi identity constraint the possibility of cosmic acceleration (especially, in the presence of cold dark matter) is established. Ghost-free massive F(R, T) gravity is also proposed. © 2013 Elsevier B.V.

Nojiri S.,Nagoya University | Odintsov S.D.,Institute Of Ciencies Of Lespai Ieec Csic
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We consider the diffeomorphism invariant gravity coupled with the ideal fluid in the nonstandard way. The Lorentz invariance of the graviton propagator in such a theory considered as perturbation over flat background turns out to be broken due to the nonstandard coupling with the ideal fluid. As a result the behavior of the propagator in the ultraviolet/infrared region indicates that some versions of such theory are (super-)renormalizable ones (with appearance of only physical transverse modes). The Friedmann-Robertson-Walker cosmology in some cases may be different from the one in general relativity with the possible power law inflationary stage. © 2010 The American Physical Society.

Bonvin C.,Kavli Institute for Cosmology Cambridge | Bonvin C.,University of Cambridge | Hui L.,Columbia University | Gaztanaga E.,Institute Of Ciencies Of Lespai Ieec Csic
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

We study the two-point cross-correlation function between two populations of galaxies: for instance, a bright population and a faint population. We show that this cross-correlation is asymmetric under the exchange of the line-of-sight coordinate of the galaxies, i.e. that the correlation is different if the bright galaxy is in front of, or behind, the faint galaxy. We give an intuitive, quasi-Newtonian derivation of all the effects that contribute to such an asymmetry in large-scale structure: gravitational redshift, Doppler shift, lensing, light-cone, evolution and Alcock-Paczynski effects; interestingly, the gravitational redshift term is exactly canceled by some of the others, assuming geodesic motion. Most of these effects are captured by previous calculations of general relativistic corrections to the observed galaxy density fluctuation; the asymmetry arises from terms that are suppressed by the ratio (H/k) - H is the Hubble constant and k is the wave number - which are more readily observable than the terms suppressed by (H/k)2. Some of the contributions to the asymmetry, however, arise from terms that are generally considered "Newtonian" - the lensing and evolution - and thus represent a contaminant in the search for general relativistic corrections. We propose methods to disentangle these different contributions. A simple method reduces the contamination to a level of 10% for redshifts z1. We also clarify the relation to recent work on measuring gravitational redshifts by stacking clusters. © 2014 American Physical Society.

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