Solar system tests in Rastall gravity

Manna, Tuhina; Rahaman, Farook; Mondal, Monimala

doi:10.1142/s0217732320500340

Cited by 17 publications

(6 citation statements)

References 49 publications

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“…OCL, as one of the cornerstones of GR [34], is not respected in all modified gravity theories, for example, it is broken in the non-minimal curvature matter coupling theories [35][36][37][38][39][40][41][42][43][44]. Rastall gravity is a pioneering theory in this area [42] in accordance with various observations [45][46][47][48][49][50][51][52][53][54][55][56][57] and its corresponding cosmology avoids the age and entropy problems arisen in the framework of the standard cosmology [58]. In fact, this theory can even provide a better platform for describing the matter dominated era compared to the Einstein theory [47].…”

Section: Introductionmentioning

confidence: 82%

Non-minimal coupling inspires the Dirac cosmological model

Moradpour,

Shabani,

Ziaie

et al. 2021

Preprint

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In the framework of the generalized Rastall theory (GRT), we study the ability of a non-minimal coupling between geometry and matter fields in order to provide a setting which allows for a variable G during the cosmic evolution. In this regard, the compatibility of this theory with Dirac hypothesis on the variations of G is investigated, and additionally, the possibility of obtaining the current accelerated universe is also addressed. In summary, our study indicates that, in GRT, having in hand the G profile, one may find the corresponding non-minimal coupling between the energy source and geometry and vise versa, in a compatible way with the current accelerated universe.

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Section: Introductionmentioning

confidence: 82%

Non-minimal coupling inspires the Dirac cosmological model

Moradpour,

Shabani,

Ziaie

et al. 2021

Preprint

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“…These models can show ghost-like behavior, instabilities, while on the other side, it has to match with experiments and observations in the low energy limit. Also in the framework of f (R, T ) gravity some interesting results have been found at solar system [6], galactic and cosmological scales.…”

Section: Introductionmentioning

confidence: 91%

Tolman VI fluid sphere in f(R,T) gravity

Mondal¹,

Rahaman²

2023

Preprint

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We analyze the behavior of relativistic spherical objects within the context of modified $f(R,T)$ gravity considering Tolman VI spacetime, where gravitational lagrangian is a function of Ricci scalar(R) and trace of energy momentum tensor(T) i.e,$ f(R,T)= R+ 2\beta T$, for some arbitrary constant $\beta$. For developing our model, we have chosen $\pounds_{m} = -p$, where $ \pounds_{m}$ represents matter lagrangian. For this investigation, we have chosen three compact stars namely PSR J1614-2230 [Mass=(1.97$\pm$ 0.4)M$_\odot$; Radius= 9.69$_{-0.02} ^{+0.02}$ Km] ,Vela X-1 [Mass=(1.77$\pm$ 0.08)M$_\odot$; Radius= 9.560$_{-0.08} ^{+0.08}$ Km] and 4U 1538-52 [Mass=(9.69)M$_\odot$; Radius= 1.97 Km]. In this theory the equation of pressure isotropy is identical to standard Einstein's theory. So all known metric potential solving Einstein's equations are also valid here. In this paper, we have investigated the effort of coupling parameter ($\beta$) on the local matter distribution. Sound of speed and adiabatic index are higher with grater values of $\beta$ while on contrary mass function and gravitational redshift are lower with higher values of $\beta$ . For supporting the theoretical results, graphical representation are also employed to analyze the physical viability of the compact stars.

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“…There exist many stable and unstable circular orbits. Another type of orbit also exist which lie between dynamically unstable and stable orbits known as "homoclinic orbits" [6][7][8]. These orbits started asymptotically closed to unstable circular orbits and ends with spiraling in and out about the central BH.…”

Section: Introductionmentioning

confidence: 99%

Lyapunov exponent, ISCO and Kolmogorov–Senai entropy for Kerr–Kiselev black hole

2021

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Geodesic motion has significant characteristics of space-time. We calculate the principle Lyapunov exponent (LE), which is the inverse of the instability timescale associated with this geodesics and Kolmogorov–Senai (KS) entropy for our rotating Kerr–Kiselev (KK) black hole. We have investigate the existence of stable/unstable equatorial circular orbits via LE and KS entropy for time-like and null circular geodesics. We have shown that both LE and KS entropy can be written in terms of the radial equation of innermost stable circular orbit (ISCO) for time-like circular orbit. Also, we computed the equation marginally bound circular orbit, which gives the radius (smallest real root) of marginally bound circular orbit (MBCO). We found that the null circular geodesics has larger angular frequency than time-like circular geodesics ($$Q_o > Q_{\sigma }$$ Q o > Q σ ). Thus, null-circular geodesics provides the fastest way to circulate KK black holes. Further, it is also to be noted that null circular geodesics has shortest orbital period $$(T_{photon}< T_{ISCO})$$ ( T photon < T ISCO ) among the all possible circular geodesics. Even null circular geodesics traverses fastest than any stable time-like circular geodesics other than the ISCO.

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Solar system tests in Rastall gravity

Cited by 17 publications

References 49 publications

Non-minimal coupling inspires the Dirac cosmological model

Non-minimal coupling inspires the Dirac cosmological model

Tolman VI fluid sphere in f(R,T) gravity

Lyapunov exponent, ISCO and Kolmogorov–Senai entropy for Kerr–Kiselev black hole

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