Role of gravitational decoupling on theoretical insights of relativistic massive compact stars in the mass gap

TL;DR

This paper investigates how gravitational decoupling influences the properties of relativistic massive compact stars in the mass gap, using a strange star model to predict their radii and moments of inertia, aligning with recent gravitational wave observations.

Contribution

It introduces a novel application of gravitational decoupling within general relativity to model mass gap compact stars, providing new constraints on their parameters and observable properties.

Findings

Maximum mass predictions exceed observed values.

Model aligns with gravitational wave event data.

Parameter variations significantly affect star properties.

Abstract

Advancements in theoretical simulations of mass gap objects, particularly those resulting from neutron star mergers and massive pulsars, play a crucial role in addressing the challenges of measuring neutron star radii. In the light of this, we have conducted a comprehensive investigation of compact objects (CSs), revealing that while the distribution of black hole masses varies based on formation mechanisms, they frequently cluster around specific values. For instance, the masses observed in GW190814 $(23.2^{+1.1}_{-1.0} \, M_{\odot})$ and GW200210 $(24.1^{+7.5}_{-4.6} M_{\odot})$ exemplify this clustering. We employed the gravitational decoupling approach within the framework of standard general relativity and thus focusing on the strange star model. This model highlights the effects of deformation adjusted by the decoupling constant and the bag function. By analyzing the mass-radius limits of mass gap objects from neutron star mergers and massive pulsars, we can effectively constrain the free parameters in our model, allowing us to predict the radii and moments of inertia for these objects. The mass-radius ($M-R$) and mass-inertia ($M-I$) profiles demonstrate the robustness of our models. It is shown that as the decoupling constant $\beta$ increases from 0 to 0.1 and the bag constant $\mathcal{B}_g$ decreases from 70 $MeV/fm^3$ to 55 $MeV/fm^3$, the maximum mass reaches $M_{max} = 2.87 \, M_\odot$ with a radius of 11.20 km. In contrast, for $\beta = 0$, the maximum mass is $M_{max} = 2.48 \, M_\odot$ with a radius of 10.69 km. Similarly, it has been exhibited that as $\beta$ decreases to 0, the maximum mass peaks at $M_{max} = 2.95 M_\odot$ for $\mathcal{B}_g = 55 MeV/fm^3$ with a radius of 11.32 km. These results not only exceed the observed masses of CSs but also correlate with recent findings from gravitational wave events like GW190814 and GW200210.