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This work analyses the hydrostatic equilibrium configurations of strange stars in a non-minimal geometry-matter coupling (GMC) theory of gravity. Those stars are made of strange quark matter, whose distribution is governed by the MIT equation of state. The non-minimal GMC theory is described by the following gravitational action: f (R , L) = R / 2 + L + σ R L , where R represents the curvature scalar, L is the matter Lagrangian density, and σ is the coupling parameter. When considering this theory, the strange stars become larger and more massive. In particular, when σ = 50 km 2 , the theory can achieve the 2.6 M ⊙ , which is suitable for describing the pulsars PSR J2215+5135 and PSR J1614-2230, and the mass of the secondary object in the GW190814 event. The 2.6 M ⊙ is a value hardly achievable in General Relativity, even considering fast rotation effects, and is also compatible with the mass of PSR J0952-0607 ( M = 2.35 ± 0.17 M ⊙ ), the heaviest and fastest pulsar in the disk of the Milky Way, recently measured, supporting the possible existence of strange quark matter in its composition. The non-minimal GMC theory can also give feasible results to describe the macroscopical features of strange star candidates. [ABSTRACT FROM AUTHOR]

An approach to estimate the spatial curvature Ω k from data independently of dynamical models is suggested, through kinematic parametrizations of the comoving distance [ D C(z)] with third-degree polynomial, of the Hubble parameter [ H (z)] with a second-degree polynomial and of the deceleration parameter [ q (z)] with first-order polynomial. All these parametrizations were done as function of redshift z. We used SNe Ia data set from Pantheon compilation with 1048 distance moduli estimated in the range 0.01 < z < 2.3 with systematic and statistical errors and a compilation of 31 H (z) data estimated from cosmic chronometers. The spatial curvature found for D C(z) parametrization was |$\Omega _{k}=-0.03^{+0.24+0.56}_{-0.30-0.53}$|⁠. The parametrization for deceleration parameter q (z) resulted in |$\Omega _{k}=-0.08^{+0.21+0.54}_{-0.27-0.45}$|⁠. The H (z) parametrization has shown incompatibilities between H (z) and SNe Ia data constraints, so these analyses were not combined. The D C(z) and q (z) parametrizations are compatible with the spatially flat universe as predicted by many inflation models and data from cosmic microwave background. This type of analysis is very appealing as it avoids any bias because it does not depend on assumptions about the matter content of the Universe for estimating Ω k . [ABSTRACT FROM AUTHOR]

We study a specific model of anisotropic strange stars in the modified |$f\left(R,\mathcal {T}\right)$| -type gravity by deriving solutions to the modified Einstein field equations representing a spherically symmetric anisotropic stellar object. We take a standard assumption that |$f(R,\mathcal {T})=R+2\chi \mathcal {T}$|⁠, where R is Ricci scalar, |$\mathcal {T}$| is the trace of the energy–momentum tensor of matter, and χ is a coupling constant. To obtain our solution to the modified Einstein equations, we successfully apply the 'embedding class one' techniques. We also consider the case when the strange quark matter (SQM) distribution is governed by the simplified MIT bag model equation of state given by |$p_r=\frac{1}{3}\left(\rho -4B\right)$|⁠, where B is bag constant. We calculate the radius of the strange star candidates by directly solving the modified TOV equation with the observed values of the mass and some parametric values of B and χ. The physical acceptability of our solutions is verified by performing several physical tests. Interestingly, besides the SQM, another type of matter distribution originates due to the effect of coupling between the matter and curvature terms in the |$f\left(R,\mathcal {T}\right)$| gravity theory. Our study shows that with decreasing the value of χ, the stellar systems under investigations become gradually massive and larger in size, turning them into less dense compact objects. It also reveals that for χ < 0 the |$f\left(R,\mathcal {T}\right)$| gravity emerges as a suitable theory for explaining the observed massive stellar objects like massive pulsars, super-Chandrasekhar stars, and magnetars, etc. which remain obscure in the standard framework of General Relativity. [ABSTRACT FROM AUTHOR]