arXiv subjects

Muhammad Lawrence Pattersons

Publications and source records attributed to Muhammad Lawrence Pattersons.

3 recordsLinked to original sources

arXiv2025

Mass--radius relations, surface redshift, and echo time of neutron-star--wormhole system with chaotic magnetic field and anisotropic matter

In this paper, we formulate neutron-star--wormhole (NSWH) systems supported by two scalar fields, allowing for both chaotic magnetic field and pressure anisotropy of the neutron fluid. The wormhole is traversable regardless of whether anisotropy of the neutron fluid and/or magnetic fields are included. In particular, the null energy condition (NEC) remains violated in the vicinity of the wormhole throat, ensuring the traversable nature of the geometry. For magnetized configurations, the resulting NSWH systems can become extremely massive, with ADM masses exceeding $8\,M_\odot$, and can exhibit large surface redshifts exceeding $z \simeq 1.5$. The system can also reach the ultracompact regime, which allows us to calculate echo time that might be produced the systems. Our calculations of the echo time indicate that it can vary depending on the chaotic magnetic field configuration and fluid anisotropy. For non-magnetized configurations, the gravitational-wave echo time is of the order of $10^{-2}-10^{-1}$ ms. For the magnetized configurations, however, it ranges from the order of $10^{-1}$ $\mu$s $-10^{-1}$ ms, suggesting that magnetic fields broaden the range of echo time. Moreover, to investigate the direct impact of the magnetic field on the echo time, we derive an explicit expression for the echo time as a function of uniform magnetic field. The resulting relation shows that the echo time decreases as the magnetic field strength increases.

gr-qc↗

arXiv2025

Mass-radius relation, moment of inertia, and tidal love numbers of anisotropic neutron stars in f (R,T) gravity

The mass-radius relation, moment of inertia, and tidal love numbers of anisotropic neutron stars (NSs) have been investigated in $f(R,T)$ gravity by imposing two equations of state (EoS). We use the simplest form $f(R,T)=R+2\beta T$ model and adopt the anisotropy approach called Horvat model. To examine the viability of our calculations, we utilize the constraints from GW170817 and GW190814 observations. Moreover, we consider three values of $\beta$, i.e. $\beta=0$, $\beta=-0.01$, $\beta=-0.02$ and four anisotropy parameters $\alpha$, i.e. $\alpha=-0.12$, $\alpha=-0.06$, $\alpha=0.06$, $\alpha=0.12$. Our findings suggest that all physical quantities depend on both parameters $\alpha$ and $\beta$. Nevertheless, the impact of $\alpha$ is much more significant than $\beta$. The calculation of masses satisfy each used constraints for specific values of $\alpha$ and $\beta$. In the case of the moment of inertia, the results are compatible with the constraint obtained from radio observation of heavy pulsar. On the other hand, the tidal deformability of the NSs composed of one EoS satisfy the GW170817 constraint while the NSs composed of the other one EoS are too small. These small numbers can be interpreted as the property of secondary object observed in GW190814. As a result, our theoretical investigation of NSs constructed with two EoS can be NSs candidates for GW170817 and GW190814, respectively.

gr-qc↗

arXiv2024

Kepler frequency and moment of inertia of rotating neutron stars with chaotic magnetic field

Rotating neutron stars (NSs) are crucial objects of study, as our understanding of them relies significantly on observational data from these rotating stars. Observations suggest that the magnetic fields of NSs range from approximately $10^{8-15}$ G. In this work, we compute the Kepler frequency and moment of inertia for rotating NSs under the influence of a chaotic magnetic field. We utilize an equation of state (EOS) incorporating nuclei in the crust and hyperons in the core, with the Hartle-Thorne formalism applied to address the rotational aspects. A magnetic field ansatz is selected, in which the magnetic field is coupled to the energy density. To examine the impact of a chaotic magnetic field on the Kepler frequency and moment of inertia, we vary the magnetic field strength. Our results indicate that an increase in magnetic field strength enhances the Kepler frequency of rotating NSs. For the moment of inertia, the effect of magnetic field variation is minimal at lower masses but becomes more pronounced as the mass exceeds $M=0.5 M_\odot$, where moment of inertia increases with increasing magnetic field. Furthermore, our results for the moment of inertia comply with constraint derived from pulsar mass measurements, data from gravitational wave events GW170817 and GW190425, and X-ray observations of emission from hotspots on NS surfaces measured by NICER.

gr-qc↗