Realistic neutron star models in f(T) gravity

Abstract

We investigate the nonrotating neutron stars in f(T) gravity with $$f(T)=T+\alpha {T}^2$$ f ( T ) = T + α T 2 , where T is the torsion scalar in the teleparallel formalism of gravity. In particular, we utilize the SLy and BSk family of equations of state for perfect fluid to describe the neutron stellar matter and search for the effects of the f(T) modification on the models of neutron stars. For positive $$\alpha $$ α , the modification results in a smaller stellar mass in comparison to general relativity, while the neutron stars will contain larger amount of matter for negative $$\alpha $$ α . Moreover, there seems to be an upper limit for the central density of the neutron stars with $$\alpha >0$$ α > 0 , beyond which the effective f(T) fluid would have a steplike phase transition in density and pressure profiles, collapsing the numerical system. We obtain the mass–radius relations of the realistic models of neutron stars and subject them to the joint constraints from the observed massive pulsars PSR J0030+0451, PSR J0740+6620, and PSR J2215+5135, and gravitational wave events GW170817 and GW190814. For the neutron star model in f(T) gravity to be able to accommodate all the mentioned data, the model parameter $$\alpha $$ α needs to be smaller than $$-\,4.295$$ - 4.295 , $$-\,6.476$$ - 6.476 , $$-\,4.4$$ - 4.4 , and $$-\,2.12$$ - 2.12 (in the unit of $${G}^2M_\odot ^2/c^4$$ G 2 M ⊙ 2 / c 4 ) for SLy, BSk19, BSk20, and BSk21 equations of state, respectively. If one considers the unknown compact object in the event GW190814 not to be a neutron star and hence excludes this dataset, the constraints can be loosened to $$\alpha <-\,0.594$$ α < - 0.594 , $$-\,3.5$$ - 3.5 , 0.4 and 1.9 (in the unit of $${G}^2M_\odot ^2/c^4$$ G 2 M ⊙ 2 / c 4 ), respectively.

Tailoring Pressure Sensitive Adhesives with H6XDI‐PEG Diacrylate for Strong Adhesive Strength and Rapid Strain Recovery

“…More importantly, the hard segment of HPD is cyclohexane, which is relatively flexible compared to the aromatic benzene of XPD. Using a Fourier‐transform infrared spectroscopy (FT‐IR), it is previously reported that the steric hindrance of the cyclohexane ring in H 6 XDI interrupts the formation of hydrogen bonds between the urethane group and polymer chains, [ 37 ] while the aromatic benzene ring structure of XDI allowed the formation of additional hydrogen bonds. This is manifested by ≈8 times longer recovery time of 0.15 XPD (142 s) compared to that of 0.15 HPD (18 s).…”

Neutron Stars on Modified Teleparallel Gravity

“…(7) Our intention is to construct a model of static compact objects, hence, considering a static and spherically symmetric line element ds 2 = γ 2 00 dt 2 − γ 2 11 dr 2 − r 2 dθ 2 − r 2 sin 2 θdϕ 2 . Thus, the vierbein or tetrad in the Schwarzschild coordinate systems is given by [29] (8) The tetrad in Eq. ( 8) is non-diagonal, but it is considered a "good tetrad" (see Ref.…”

“…Sometimes these theories may fail in solar system scales, but in several cases, they are still useful in the context of effective theories. Applications of modified theories of gravity have been discussed on several areas like compact objects, early universe, gravitational waves and so on [8,23,24,[26][27][28][29][30][31][32][33][34].…”

A novel definition of complexity in torsion based theory

“…The study of the neutron star is also a hot topic in literature. In f (T ) gravity, the contribution about the inspection of neutron star with the aid of model f (T ) = T (1 + αT ) is carried out by Lin et al [21]. They found that in the case of a negative value of α, the large size of the matter is held by the neutron star.…”