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We explore the structural properties of quark stars (QSs) in a modified gravity theory known as f(R,T)gravity, which introduces a coupling between matter and spacetime geometry, through a basic linear functional form f(R,T)=R+2βT. Our study focuses on QSs made of interacting quark matter (IQM) as an equation of state. We first derive the modified Tolman-Oppenheimer-Volkoff (TOV) equations for anisotropic matter in a spherically symmetric context and solve them numerically to obtain the structural properties of QSs. Stability is analyzed through static stability analysis, critical adiabatic indices, and sound speed profiles. Using astrophysical constraints from the “black widow” pulsar PSR J0952-0607 and the GW190814 event, we calibrate our model parameters. Our results indicate that with higher λ¯, both the maximum mass and radius of QSs increase, achieving a maximum mass of over 2M⊙, peaking at 3.15M⊙for a radius of 14.90kmat λ¯=0.9. The maximum compactness also rises to M/R=0.313while adhering to the Buchdahl limit. Additionally, varying βin the range [−0.2,0.2]with fixed parameters shows that lower βvalues enhance the maximum mass of QSs, reaching 2.65M⊙at β=−0.2, with the compactness remaining around M/R≈0.3. Furthermore, changes in μfrom [−1.0,1.0]significantly affect maximum mass; at μ=1.0, the mass peaks at 3.15M⊙and decrease to 2.68M⊙at μ=0. The compactness increases with μ, indicating that anisotropic pressure influences the M−Rrelations. In summary, our findings reveal that the parameters λ¯, β, and μplay crucial roles in shaping the physical properties of QSs in the f(R,T)gravity framework, consistent with astrophysical observations from pulsars and gravitational wave events.

In this paper, we investigate the effects of electric field gradients on the secondary component of GW190814 and other binary compact objects. Using general relativistic equations, we derive a model with three conditions and analyze its metric potentials, electric charge, energy density, stresses, and anisotropy parameter. The metric potentials in our analysis match the Schwarzschild exterior at the stellar surface, exhibiting smooth behavior without any central singularity. The electric charge increases from zero at the core to a maximum at the surface, indicating an outward electric force. The energy density, radial and tangential pressures, and anisotropy all demonstrate well-behaved trends. The model is found stable based on the Harrison-Zeldovich-Novikov criteria, adiabatic index, and causality. Investigating the electric charge influence, we find increased charge leads to decreasing pressures and lower central adiabatic index, suggesting the need to optimize charge for long-term stability. The analysis of mass-radius ratio and moment of inertia-mass demonstrates the model's ability to capture the equation of state (EOS) stiffness. Finally, from the M−Rand I−Mcurves we have shown that the mass obtained for the slowly rotating star is higher than the non-rotating case due to the contribution from rotational energy 12IΩ2for all values of E0. It is very surprising to find that the electric field per radial distance i.e. E/r=E0is maximum at a particular mass for a chosen radius, specifically for r(km), MNR(M⊙), and E0max×10−4(/km4). The electric field per unit radius also influences the EOS significantly with overall form Pr=aρ−bρ2−cfor all a,b,c>0. This means that the EOS contains quark matter, dark energy, and exotic matters.

In this paper, we studied anisotropic models to describe compact stellar objects with a spherically symmetric matter distribution using modified f(R)gravity. To accomplish this goal, we examined two distinct models within the f(R)theory of gravity. We investigated the use of the Durgapal and Fuloria analog metric potentials to construct a stellar model by solving the Einstein Field equations. Our analysis includes a discussion of the generalized Darmois-Israel junction condition, crucial for smoothly linking the interior region to the Schwarzschild exterior metric at the star’s boundary hypersurface within the framework of f(R)gravity. This junction condition requires a non-zero pressure at the boundary, which is directly related to the non-linear terms present in f(R)gravity. These conditions are often overlooked by many researchers in their exploration of compact stellar models. In our study, we utilized generalized boundary conditions to determine model parameters. Furthermore, we obtained these parameters using observational data from several compact stars, including 4U1538-52, SAX J 1808.4-3658, EXO 1785-248, Cen X-3, 4U1820-30, PSR J1903+327, 4U1608-52, and PSR J1614-2230. This innovative approach allowed us to conduct a comprehensive analysis of models and their physical validity. We performed various physical tests such as anisotropy, equilibrium conditions, stability, energy-density constraints, mass function, compactness, redshift, and adiabatic index to evaluate the feasibility of our models.

In this work, we construct three different models of static wormhole (WH) geometries within the realm of f(R,Lm)gravity theory. We start by deriving the corresponding field equations for the Morris–Thorne WH geometry in the context of anisotropic matter distribution under the generic form of f(R,Lm)gravity. By adequately specifying the key features of three different shape function models generated with different assumptions about their matter content, and assuming that WHs exert no tidal force by setting the gravitational redshift function to be a constant or φ′(r)=0, we disclose a variety of exact WH solutions in the theory. Our exact solutions for f(R,Lm)show that for all three classes of WHs found, the energy density is consistently positive in all spacetime, while the radial pressure is negative. This signifies that exotic matter is mandatory for the existence of WHs in f(R,Lm)gravity. We have also applied the energy conditions (ECs) for the WHs’ physical content and found that exact WH models are filled with exotic matter that violates the necessary ECs throughout spacetime and makes them compatible and traversable.

At super-saturation densities, quarks in the core of neutron stars (NSs) have been a subject of intense investigation for last few decades. In particular, an intriguing conjecture has emerged suggesting that the true ground state of hadronic matter may be strange quark matter (SQM). In the present manuscript, we study internal structure and the physical properties of quark stars (QSs) in energy-momentum squared gravity (EMSG) with MIT bag model equations of state (EoS). An important feature of this theory is the addition of the term f(TμνTμν)to the Einstein-Hilbert action. This modification in the action lead to changes in the right-hand side of Einstein's field equations (EFE). We obtain mass-radius relations for a spherically symmetric configuration supported by the anisotropic fluid matter distribution and solved the hydrostatic equilibrium equations numerically in the framework of EMSG. In addition, we present and discuss the stability of stellar structure depending on the model parameters.

In this paper, we are focused on studying the possibility of providing a new well-behaved class of exact solutions for viable anisotropic stellar systems with dust and phantom regimes in the framework of Rastall gravity theory. This gravity theory modifies the matter sector only, incorporating new ingredients to the physical parameters that describe the model like charge density, electric field, density, and pressure components. Furthermore, other significant amounts are influenced, such as subliminal speeds of the pressure waves in radial and transversal directions, observational parameters such as the surface redshift associated with the total mass Mand the radius Rof the compact stellar configurations. Likewise, a transcendent mechanism such as equilibrium via generalized Tolman–Oppenheimer–Volkoff equation and stability of the stellar system is upset. The unidentified constraints are evaluated via the boundary conditions along with the dust and phantom models to describe as exterior space–times considering experimental statistics of five different stars i.e., EXO 1785 - 248, SMC X - 1, SAX J 1808.4 - 3658, 4U 1538 - 52, and HER X - 1. Various physical aspects have been analyzed with the help of modified dynamical equations. Exclusively, all the stellar configurations under observations are realistic, stable, and are free from all singularities. After witnessing the minor differences between our proposed models in both cases, Andréasson’s limit M≤R/3+R/9+Q2/3Rhas been fulfilled as required by the charged stellar structures. In such an astrophysical scenario, our new results provide circumstantial evidence in favor of super-massive pulsars.

This manuscript explores the physical aspects of compact stars in f(τ,T)gravity, where τand Texpress the torsion and trace of the energy–momentum tensor. To achieve this goal, we consider a spherically symmetric spacetime with an anisotropic source of fluid. In particular, the Karori–Barua spacetime is considered to explore the solution of compact stars. In addition, we select three specific types of compact stars models, namely PSRJ1416−2230, 4U1608−52, and CenX−3. We develop the field equations using the Karori–Barua spacetime with some specific form of f(τ,T)gravity. In addition, we consider the Schwarzschild geometry for the matching conditions at the boundary. Then, we calculate the values of all the relevant parameters by imposing matching conditions. We provide detailed graphical analyses for the physical acceptability of different parameters, namely energy density, pressure, anisotropy, and gradient. We also examine the stability of compact stars by exploring energy conditions, equations of state, conditions of causality, redshift functions, mass functions, and compactness functions. Finally, we find that the solutions we obtained are physically viable in modified physical acceptability and also it has good properties for the compact star models.

We have provided a new exact solution for anisotropic compact stars to the field equations of f(R,T)-gravity via a decoupling technique, with the assumption of a linear f(T)function and the modified Durgapal-Fuloria metric ansatz. By deforming the radial component of the metric and introducing Pseudo-Isothermal (PI) dark matter (DM) as a new source to the anisotropic seed solution in the process of minimally gravitational decoupling, we have obtained a non-singular solution that meets all physical criteria related to effective density, effective pressure, effective anisotropy, and energy conditions. The present system satisfies the modified Tolman-Oppenheimer-Volkoff equation and achieves stable equilibrium, fulfilling stability criteria such as the adiabatic condition, Herrera cracking concept, and Harrison-Zeldovich-Novikov condition. The influence of minimally gravitational decoupling on the characteristics of the system has been illustrated graphically by varying the decoupling constant (γ). The mass-radius relations are linked to observational constraints and examined for anisotropic stellar systems with and without the effect of minimally gravitational decoupling in both general relativity (GR) and f(R,T)-gravity. We found that increasing values of the f(R,T)-gravity parameter (χ) and γreduce the maximum allowable mass of the star. Therefore, increasing the effects of minimally gravitational decoupling and the PI-DM content, subject to the Durgapal-Fuloria metric potential ansatz, cannot support highly compact and supermassive astrophysical objects.

This study delves into the distinctive characteristics of wormhole models in the context of de Rham-Gabadadze-Tolley (dRGT) massive gravity, providing insights into their theoretical behavior and stability. We use a null zero complexity factor to find the wormhole shape function for Model I. Additionally, we solve analytically the modified field equations describing wormhole for a given choice of logarithmic redshift function, exploiting the Karmarkar condition for embedding class one metrics for Model II. To achieve this, we analyze the wormhole geometry in a static spherical spacetime with an anisotropic matter configuration. The study investigates a number of parameters, including density, energy conditions, equation of state parameter, adiabatic sound velocity, and equilibrium condition. The solution shows a traversable wormhole that violates the null energy criterion and equilibrium state for certain ranges of free parameters. We employ adiabatic sound velocity analysis to concentrate on the stability of the wormhole. Furthermore, by using the equation of state parameter (ω), we conclude that both models end up in the phantom dark energy region. Finally, our findings highlight distinct photon deflection behaviors in dRTG massive gravity, with Model II showing negative angles indicative of repulsive gravity, while Model I exhibits positive angles, underscoring significant differences in gravitational dynamics.

In the current analysis, we investigate the possible existence of generalized Wormhole models within the galactic halo region by analyzing specific dark matter models. The observational data is checked in the framework of torsion within minimal matter coupling gravity. By using the variational approach modified versions of the field equations under the anisotropic source of matter are calculated. To discuss the specific necessary characteristics of the embedded wormhole geometry, we have analyzed the energy conditions under the effect of dark matter halos. We consider two embedded wormhole-specific shape functions in terms of the tortoise coordinate for the current study. Further, we compare different wormhole solutions for the different regional ranges depending on the involved parametric values. To check the effect of the dark matter halos, we use the observational data within the signature of the M87 galaxy and the Milky Way galaxy.

In the present paper, we have explored the existence of compact structures describing anisotropic matter distributions within the framework of f(R,T)theory, where Ris Ricci scalar and Tis a trace of energy–momentum tensor. We have chosen f(R,T)as a linear function of Rand T, i.e., f(R,T)=R+2χTwith χas matter-geometry coupling constant. We employed the embedding class one technique in order to obtain a full space–time description inside the stellar configuration. After specifying space–time geometry, we determined the complete solution of modified field equations by using the MIT-Bag model equation of state, i.e., pr=13(ρ−4Bg)that describes the strange quark matter distribution inside the stellar system, where Bgrepresents a bag constant. We checked the physical viability of the solution through different physical tests. Moreover, using observed mass values for the various strange star candidates, we have predicted the exact radii by taking distinct values for χand Bg. Accordingly, we thoroughly show that with decreasing the value of χ, the stellar systems under examinations become progressively massive and larger in size, transforming them into less dense compact objects. It additionally uncovers that for χ<0the fR,Tgravity arises as an adequate theory for explaining the magnetars, super-Chandrasekhar stars and massive pulsars, which are assumed to be the reason behind the overluminous SNeIa e.g. SN 2003fg, SN 2006gz, SN 2007if, SN 2009dc and remain mostly unexplained in the background of general relativity.