Observational constraints in metric-affine gravity

We derive the main classical gravitational tests for a recently found vacuum solution with spin and dilation charges in the framework of Metric-Affine gauge theory of gravity. Using the results of the perihelion precession of the star S2 by the GRAVITY collaboration and the gravitational redshift of Sirius B white dwarf we constrain the corrections provided by the torsion and nonmetricity fields for these effects.

The Physical Cause of Planetary Perihelion Precession

According to the revised gravitation formula, the gravitational force on planets in the solar system is mainly provided by the sun, and only when the planet is far enough from the sun to treat the sun as a particle, the gravitational force on the planet coincides well with Newton's gravitational formula. The closer the planet is to the sun, the more the gravitational force on the planet deviates from (greater than) the value calculated by Newton's universal gravitation formula. The precession of the planet's perihelion is due to this property of gravity.

Constraints on long range force from perihelion precession of planets in a gauged $$L_e-L_{\mu ,\tau }$$ scenario

The standard model leptons can be gauged in an anomaly free way by three possible gauge symmetries namely $${L_e-L_\mu }$$ L e - L μ , $${L_e-L_\tau }$$ L e - L τ , and $${L_\mu -L_\tau }$$ L μ - L τ . Of these, $${L_e-L_\mu }$$ L e - L μ and $${L_e-L_\tau }$$ L e - L τ forces can mediate between the Sun and the planets and change the perihelion precession of planetary orbits. It is well known that a deviation from the $$1/r^2$$ 1 / r 2 Newtonian force can give rise to a perihelion advancement in the planetary orbit, for instance, as in the well known case of Einstein’s gravity (GR) which was tested from the observation of the perihelion advancement of the Mercury. We consider the long range Yukawa potential which arises between the Sun and the planets if the mass of the gauge boson is $$M_{Z^{\prime }}\le \mathcal {O}(10^{-19})\mathrm {eV}$$ M Z ′ ≤ O ( 10 - 19 ) eV . We derive the formula of perihelion advancement for Yukawa type fifth force due to the mediation of such $$U(1)_{L_e-L_{\mu ,\tau }}$$ U ( 1 ) L e - L μ , τ gauge bosons. The perihelion advancement for Yukawa potential is proportional to the square of the semi major axis of the orbit for small $$M_{Z^{\prime }}$$ M Z ′ , unlike GR where it is largest for the nearest planet. For higher values of $$M_{Z^{\prime }}$$ M Z ′ , an exponential suppression of the perihelion advancement occurs. We take the observational limits for all planets for which the perihelion advancement is measured and we obtain the upper bound on the gauge boson coupling g for all the planets. The Mars gives the stronger bound on g for the mass range $$\le 10^{-19}\mathrm {eV}$$ ≤ 10 - 19 eV and we obtain the exclusion plot. This mass range of gauge boson can be a possible candidate of fuzzy dark matter whose effect can therefore be observed in the precession measurement of the planetary orbits.

Field Approach for General Relativity

The general theory of relativity is based on expressing gravity by means of the metric tensor and its elements instead of some fields as in electrodynamics. This work starts with by defining some vector fields for metric or metric tensor. After metric and metric tensor are expressed in terms of these fields, the geodesic equations and Einstein equations are derived for these fields. Finally, perihelion precession and light deflection are recalculated, as two different applications of the introduced fields.

Precession of timelike bound orbits in Kerr spacetime

Astrometric observations of S-stars provide a unique opportunity to probe the nature of Sagittarius-A* (Sgr-A*). In view of this, it has become important to understand the nature and behavior of timelike bound trajectories of particles around a massive central object. It is known now that whereas the Schwarzschild black hole does not allow the negative precession for the S-stars, the naked singularity spacetimes can admit the positive as well as negative precession for the bound timelike orbits. In this context, we study the perihelion precession of a test particle in the Kerr spacetime geometry. Considering some approximations, we investigate whether the timelike bound orbits of a test particle in Kerr spacetime can have negative precession. In this paper, we only consider low eccentric timelike equatorial orbits. With these considerations, we find that in Kerr spacetimes, negative precession of timelike bound orbits is not allowed.

Constraints on scalar–tensor theory of gravity by solar system tests

We study the motion of particles in the background of a scalar–tensor theory of gravity in which the scalar field is kinetically coupled to the Einstein tensor. We constrain the value of the derivative parameter z through solar system tests. By considering the perihelion precession we obtain the constraint $$\sqrt{z}/m_{\mathrm{p}} > 2.6\times 10^{12}$$ z / m p > 2.6 × 10 12 m, the gravitational redshift $$\frac{\sqrt{z}}{m_{\mathrm{p}}}>2.7\times 10^{\,10}$$ z m p > 2.7 × 10 10 m, the deflection of light $$\sqrt{z}/m_{\mathrm{p}} > 1.6 \times 10^{11}$$ z / m p > 1.6 × 10 11 m, and the gravitational time delay $$\sqrt{z}/m_{\mathrm{p}} > 7.9 \times 10^{12}$$ z / m p > 7.9 × 10 12 m; thereby, our results show that it is possible to constrain the value of the z parameter in agreement with the observational tests that have been considered.

Perspectives of perihelion precession in torsion modified gravity

Killing symmetries are revisited in [Formula: see text] bulk geometric torsion (GT) perturbation theory to investigate the perihelion precession. Computation reveals a nonperturbative (NP) modification to the precession known in General Relativity (GR). Remarkably the analysis reassures our proposed holographic correspondence between a perturbative GT in bulk and a boundary GR coupled to [Formula: see text]. In fact, the topological correction is sourced by a non-Newtonian potential in GR and we identify it with an “electro-gravito” (EG) dipole. Interestingly, the dipole correction is shown to possess its origin in a [Formula: see text]-form underlying a propagating GT and leads to a NP gravity in [Formula: see text].