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Anglani R.,CNR Institute of Intelligent Systems for Automation | Casalbuoni R.,University of Florence | Ciminale M.,dellUniversita e della Ricerca | Ippolito N.,National Institute of Nuclear Physics, Italy | And 3 more authors.
Reviews of Modern Physics | Year: 2014

Inhomogeneous superconductors and inhomogeneous superfluids appear in a variety of contexts including quark matter at extreme densities, fermionic systems of cold atoms, type-II cuprates, and organic superconductors. In the present review the focus is on properties of quark matter at high baryonic density, which may exist in the interior of compact stars. The conditions realized in these stellar objects tend to disfavor standard symmetric BCS pairing and may favor an inhomogeneous color superconducting phase. The properties of inhomogeneous color superconductors are discussed in detail and in particular of crystalline color superconductors. The possible astrophysical signatures associated with the presence of crystalline color superconducting phases within the core of compact stars are also reviewed. © 2014 American Physical Society. Source

Iorio L.,dellUniversita e della Ricerca
Monthly Notices of the Royal Astronomical Society: Letters | Year: 2014

The recent discovery of the Sedna-like dwarf planet 2012 VP113 by Trujillo and Sheppard has revamped the old-fashioned hypothesis that a still unseen trans-Plutonian object of planetary size, variously dubbed over the years as Planet X, Tyche and Telisto, might lurk in the distant peripheries of the Solar system. This time, the presence of a super-Earth with mass mX = 2-15m at a distance dX ≈ 200-300 astronomical units (au) has been proposed to explain the observed clustering of the arguments of perihelion ω near ω ≈ 0° but not ω ≈ 180° for Sedna, 2012 VP113 and other minor bodies of the Solar system with perihelion distances q > 30 au and semimajor axes a > 150 au. Actually, such a scenario is strongly disfavoured by the latest constraintsΔ π{variant} on the anomalous perihelion precessions of some Solar system planets obtained with the INPOP and EPM ephemerides. Indeed, they yield dX ≃ 496-570 au (mX = 2m) and dX ≃ 970-1111 au (mX = 15m). Much tighter constraints could be obtained in the near future from the New Horizons mission to Pluto. © 2014 The Author. Source

Iorio L.,dellUniversita e della Ricerca | Saridakis E.N.,National Technical University of Athens | Saridakis E.N.,Baylor University
Monthly Notices of the Royal Astronomical Society | Year: 2012

We use recent observations of Solar system orbital motions in order to constrain f(T) gravity. In particular, imposing a quadratic f(T) correction to the linear-in-T form, which is a good approximation for every realistic case, we extract the spherical solutions of the theory. Using these spherical solutions to describe the Sun's gravitational field, we use recently determined supplementary advances of planetary perihelia, to infer upper bounds on the allowed f(T) corrections. We find that the maximal allowed divergence of the gravitational potential in f(T) gravity from that in the teleparallel equivalent of General Relativity is of the order of 6.2 × 10 -10, in the applicability region of our analysis. This is much smaller than the corresponding (significantly small too) divergence that is predicted from cosmological observations, as expected. Such a tiny allowed divergence from the linear form should be taken into account in f(T) model building. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS. Source

Iorio L.,dellUniversita e della Ricerca
Monthly Notices of the Royal Astronomical Society | Year: 2013

Atwo-body system hypothetically affected by an additional radial acceleration Hvr,where vr is the radial velocity of the binary's proper orbital motion, would experience long-term temporal changes of both its semimajor axis a and the eccentricity e qualitatively different from any other standard competing effect for them. Contrary to what one might reasonably expect, the analytical expressions of such rates do not vanish in the limit M←0, where M is the mass of the primary, being independent of it. This is a general requirement that any potentially viable physical mechanism able to provide such a putative acceleration should meet. Nonetheless, if H had the same value H0 of the Hubble parameter at present epoch, such rates of change would have magnitude close to the present-day level of accuracy in determining planetary orbital motions in our Solar system. However, general relativity, applied to a localized gravitationally bound binary system immersed in an expanding Friedmann-Lemaître-Robertson-Walker, does not predict the existence of such a putative radial acceleration at Newtonian level. Instead, it was recently shown in the literature that an acceleration of the order of H and directed along the velocity v of the test particle occurs at post-Newtonian level. We worked out its orbital effects finding well-behaved secular rates of change for both a and e proportional to the Schwarzschild radius rs of the primary. Theirmagnitude is quite small: the rate of change of a amounts to just 20 μm per century in our Solar system. Finally, we discussed certain basic criteria of viability that modified models of gravity should generally meet when their observable effects are calculated. ©2012 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society. Source

Iorio L.,dellUniversita e della Ricerca
Classical and Quantum Gravity | Year: 2013

The dynamics of non-spherical systems described by modified Newtonian dynamics (MOND) theories arising from generalizations of the Poisson equation is affected by an extra MONDian quadrupolar potential φQ even if they are isolated (no external field effect) and if they are in the deep Newtonian regime. In general MOND theories quickly approaching Newtonian dynamics for accelerations beyond A0, φQ is proportional to a coefficient α ∼ 1, while in MOND models becoming Newtonian beyond κA0, κ ≫ 1, it is enhanced by κ2. We analytically work out some orbital effects due to φQ in the framework of QUMOND and compare them with the latest observational determinations of Solar System's planetary dynamics, exoplanets, double lined spectroscopic binary stars and binary radio pulsars. The current admissible range for the anomalous perihelion precession of Saturn -0.5 mas cty-1 mas cty-1 yields |κ| 3.5 × 10 3, while the radial velocity of α Cen AB allows us to infer |κ| 6.2 × 104 (A) and |κ| 4.2 × 10 4 (B). © 2013 IOP Publishing Ltd. Source

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