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A. Errehymy

Publications and source records attributed to A. Errehymy.

20 records · Page 2Linked to original sources

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

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 $β$ 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 $β= 0$, the maximum mass is $M_{max} = 2.48 \, M_\odot$ with a radius of 10.69 km. Similarly, it has been exhibited that as $β$ 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.

astro-ph.HE↗

Exploring accelerated expansion in the universe: A study of $f(Q,T)$ gravity with parameterized EoS and cosmological constraints

The study conducted in this research paper utilizes the $f(Q,T)$ gravity, where $Q$ represents non-metricity and $T$ represents the trace of the energy-momentum tensor, to investigate the accelerated expansion of the universe. To complete the study, an effective EoS with one parameter $α$, is parameterized as $ω_{eff}=-\frac{3}{α(1+z)^{3}+3}$. The linear version of $f(Q,T)=-Q+σT$ is also considered, where $σ$ is a constant. By constraining the model with six BAO points, 57 Hubble points, and 1048 Pantheon sample datasets, the parameters $α$ and $σ$ are determined to best match the data. The cosmological parameters and energy conditions for the model are derived and examined. The results show that the model is in good agreement with observations, and can serve as a valuable starting point for analyzing FLRW models in the $f(Q,T)$ theory of gravity.

astro-ph.CO↗