International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei

Prato, Italy

International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei

Prato, Italy
SEARCH FILTERS
Time filter
Source Type

Iorio L.,R.A.U.M. | Iorio L.,International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei
Earth, Moon and Planets | Year: 2012

We analytically work out the long-term orbital perturbations induced by a homogeneous circular ring of radius Rr and mass mr on the motion of a test particle in the cases (I): r ≥ Rr and (II): r < Rr. In order to extend the validity of our analysis to the orbital configurations of, e. g., some proposed spacecraft-based mission for fundamental physics like LISA and ASTROD, of possible annuli around the supermassive black hole in Sgr A* coming from tidal disruptions of incoming gas clouds, and to the effect of artificial space debris belts around the Earth, we do not restrict ourselves to the case in which the ring and the orbit of the perturbed particle lie just in the same plane. From the corrections δ π{variant}̇(meas) to the standard secular perihelion precessions, recently determined by a team of astronomers for some planets of the Solar System, we infer upper bounds on mr for various putative and known annular matter distributions of natural origin (close circumsolar ring with Rr = 0.02 - 0.13 au, dust ring with Rr = 1 au, minor asteroids, Trans-Neptunian Objects). We find mr < 1.4 × 10-4 m⊕(circumsolar ring with Rr = 0.02 au), mr < 2.6 × 10-6 m⊕ (circumsolar ring with Rr = 0.13 au), mr < 8.8 × 10-7 m⊕ (ring with Rr = 1 au), mr < 7.3 × 10-12 m⊙ (asteroidal ring with Rr = 2.80 au), mr < 1.1 × 10-11 m⊙ (asteroidal ring with Rr = 3.14 au), mr < 2.0 × 10-8 m⊙ (TNOs ring with Rr = 43 au). In principle, our analysis is valid both for baryonic and non-baryonic Dark Matter distributions. © 2012 Springer Science+Business Media B.V.


Iorio L.,R.A.U.M. | Iorio L.,International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei | Luca Ruggiero M.,Polytechnic University of Turin | Luca Ruggiero M.,National Institute of Nuclear Physics, Italy | Corda C.,International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei
Acta Astronautica | Year: 2013

A realistic assessment of the uncertainties in the even zonals of a given geopotential model must be made by directly comparing its coefficients with those of a wholly independent solution of superior formal accuracy. Otherwise, a favorable selective bias is introduced in the evaluation of the total error budget of the LAGEOS-based Lense-Thirring tests yielding likely too optimistic figures for it. By applying a novel approach which recently appeared in the literature, the second (ℓ=4) and the third (ℓ=6) even zonals turn out to be uncertain at a 2-3×10-11(ℓ=4) and 3-4×10 -11(ℓ=6) level, respectively, yielding a total gravitational error of about 27-28%, with an upper bound of 37-39%. The results by Ries et al. themselves yield an upper bound for it of about 33%. The low-degree even zonals are not exclusively determined from the GRACE Satellite-to-Satellite Tracking (SST) range since they affect it with long-period, secular-like signatures over orbital arcs longer than one orbital period: GRACE SST is not accurately sensitive to such signals. Conversely, general relativity affects it with short-period effects as well. Thus, the issue of the a priori "imprinting" of general relativity itself in the GRACE-based models used so far remains open. © 2013 Elsevier Ltd. All rights reserved.


Iorio L.,International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei | Iorio L.,R.A.U.M.
General Relativity and Gravitation | Year: 2012

We put independent model dynamical constraints on the net electric charge Q of some astronomical and astrophysical objects by assuming that their exterior spacetimes are described by the Reissner-Nordström, metric, which induces an additional potential U RN ∝ Q 2r -2. From the current bounds Δ π{variant}̇ on any anomalies in the secular perihelion rate π{variant}̇ of Mercury and the Earth-mercury ranging Δρ, we have {pipe}Q ⊙{pipe} ≲ 1-0.4 × 10 18 C. Such constraints are ~60-200 times tighter than those recently inferred in literature. For the Earth, the perigee precession of the Moon, determined with the Lunar Laser Ranging technique, and the intersatellite ranging Δρ for the GRACE mission yield {pipe}Q ⊕{pipe} ≲ 5-0.4 × 10 14 C. The periastron rate of the double pulsar PSR J0737-3039A/B system allows to infer {pipe}Q NS{pipe} ≲ 5 × 10 19 C. According to the perinigricon precession of the main sequence S2 star in Sgr A*, the electric charge carried by the compact object hosted in the Galactic Center may be as large as {pipe}Q •{pipe} ≲ 4 × 10 27 C. Our results extend to other hypothetical power-law interactions inducing extra-potentials U pert = Ψr -2 as well. It turns out that the terrestrial GRACE mission yields the tightest constraint on the parameter Ψ, assumed as a universal constant, amounting to {pipe}Ψ{pipe} ≲ 5 × 10 9 m 4 s -2. © 2012 Springer Science+Business Media, LLC.


Iorio L.,R.A.U.M. | Iorio L.,International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei | Iorio L.,Viale Unita Of Italia 68
General Relativity and Gravitation | Year: 2012

We analytically compute the orbital effects induced on the motion of a spinning particle geodesically traveling around a central rotating body by the general relativistic two-body spin-spin and spin-orbit leading-order interactions. Concerning the spin-orbit term, we compute the long-term variations due to the particle's spin by finding secular precessions for the inclination I of the particle's orbit, its longitude of the ascending node Ω and the longitude of pericenter π. Moreover, we generalize the well-known Lense-Thirring precessions to a generic orientation of the source's angular momentum by obtaining an entirely new effect represented by a secular precession of I, and additional secular precessions of Ω and π as well. The spin-spin interaction is responsible of gravitational effects à la Stern-Gerlach consisting of secular precessions of I,Ω,π and the mean anomaly M. Such results are obtained without resorting to any approximations either in the particle's eccentricity e or in its inclination I; moreover, no preferred orientations of both the system's angular momenta are adopted. Their generality allows them to be applied to a variety of astronomical and astrophysical scenarios like, e.g., the Sun and its planets and the double pulsar PSR J0737-3039A/B. It turns out that the orbital precessions caused by the spin-spin and the spin-orbit perturbations due to the less massive body are below the current measurability level, especially for the solar system and the Stern-Gerlach effects. Concerning the solar Lense-Thirring precessions, the slight misalignment of the solar equator with respect to the ecliptic reduces the gravitomagnetic node precession of Mercury down to a 0.08 mas per century level with respect to the standard value of 1 mas per century obtained by aligning the z axis with the Sun's angular momentum. The new inclination precession is as large as 0.06 mas per century, while the perihelion's rate remains substantially unchanged, amounting to -2 mas per century. Further studies may be devoted to the extrasolar planets which exhibit a rich variety of orbital and rotational configurations. © 2011 Springer Science+Business Media, LLC.


Iorio L.,R.A.U.M. | Iorio L.,International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei | Iorio L.,Viale Unita Of Italia
Solar Physics | Year: 2012

The angular momentum of a star is an important astrophysical quantity related to its internal structure, formation, and evolution. Helioseismology yields S ⊙= 1.92 × 10 41 kg m 2 s -1 for the angular momentum of the Sun. We show how it should be possible to constrain it in a near future by using the gravitomagnetic Lense-Thirring effect predicted by General Relativity for the orbit of a test particle moving around a central rotating body. We also discuss the present-day situation in view of the latest determinations of the supplementary perihelion precession, of Mercury. A fit by Fienga et al. (Celestial Mech. Dynamical Astron. 111, 363, 2011) of the dynamical models of several standard forces acting on the planets of the solar system to a long data record yielded, milliarcseconds per century. The modeled forces did not include the Lense-Thirring effect itself, which is expected to be as large as, from helioseismology-based values of S ⊙. By assuming the validity of General Relativity, from its theoretical prediction for the gravitomagnetic perihelion precession of Mercury, one can straightforwardly infer S ⊙ ≤ 0.95 × 10 41kg, m 2, s -1. It disagrees with the currently available values from helioseismology. Possible sources for the present discrepancy are examined. Given the current level of accuracy in the Mercury ephemerides, the gravitomagnetic force of the Sun should be included in their force models. MESSENGER, in orbit around Mercury since March 2011, will collect science data until 2013, while BepiColombo, to be launched in 2015, should reach Mercury in 2022 for a year-long science phase: the analysis of their data will be important in effectively constraining S ⊙ in about a decade or, perhaps, even less. © 2012 Springer Science+Business Media B.V.


Corda C.,International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei | Mosquera Cuesta H.J.,International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei | Mosquera Cuesta H.J.,Acaraú Valley State University | Mosquera Cuesta H.J.,Institute Cosmologia | Lorduy Gomez R.,EAFIT University
Astroparticle Physics | Year: 2012

We show that in the framework of R 2 gravity and in the linearized approach it is possible to obtain spherically symmetric stationary states that can be used as a model for galaxies. Such approach could represent a solution to the Dark Matter Problem. In fact, in the model, the Ricci curvature generates a high energy term that can in principle be identified as the dark matter field making up the galaxy. The model can also help to have a better understanding on the theoretical basis of Einstein-Vlasov systems. Specifically, we discuss, in the linearized R 2 gravity, the solutions of a Klein-Gordon equation for the spacetime curvature. Such solutions describe high energy scalarons, a field that in the context of galactic dynamics can be interpreted like the no-light-emitting galactic component. That is, these particles can be figured out like wave-packets showing stationary solutions in the Einstein-Vlasov system. In such approximation, the energy of the particles can be thought of as the galactic dark matter component that guarantees the galaxy equilibrium. Thus, because of the high energy of such particles the coupling constant of the R 2-term in the gravitational action comes to be very small with respect to the linear term R. In this way, the deviation from standard General Relativity is very weak, and in principle the theory could pass the Solar System tests. As pertinent to the issue under analysis in this paper, we present an analysis on the gravitational lensing phenomena within this framework. Although the main goal of this paper is to give a potential solution to the Dark Matter Problem within galaxies, we add a section where we show that an important property of the Bullet Cluster can in principle be explained in the scenario introduced in this work. To the end, we discuss the generic prospective to give rise to the Dark Matter component of most galaxies within extended gravity. © 2011 Elsevier B.V. All rights reserved.


Iorio L.,University e della Ricerca Istruzione | Iorio L.,Viale Unita Of Italia 68 | Iorio L.,International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei
Classical and Quantum Gravity | Year: 2012

We analytically work out the long-term rates of the change of the six osculating Keplerian orbital elements of a test particle acted upon by the Lorentzviolating gravitomagnetic acceleration due to a static body, as predicted by the standard model extension. We neither restrict to any specific spatial orientation for the symmetry-violating vector s = {-s -01,-s -02,-s -03} nor make a priori simplifying assumptions concerning the orbital configuration of the perturbed test particle. Thus, our results are quite general, and can be applied for sensitivity analyses to a variety of specific astronomical and astrophysical scenarios. We find that, apart from the semimajor axis a, all the other orbital elements undergo non-vanishing secular variations. By comparing our results to the latest determinations of the supplementary advances of the perihelia of some planets of the solar system, we preliminarily obtain sx = (0.9 ± 1.5) x 10 -8, sy = (-4 ± 6) x 10 -9 and sz = (0.3 ± 1) x 10 -9. Bounds from the terrestrial LAGEOS and LAGEOS II satellites are of the order of s ∼ 10 -3-10 -4. © 2012 IOP Publishing Ltd.

Loading International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei collaborators
Loading International Institute for Theoretical Physics and Advanced Mathematics Einstein Galilei collaborators