Quadratic Rastall Gravity: from low-mass HESS J1731-347 to high-mass PSR J0952-0607 pulsars

Abstract

Similar to Rastall gravity we introduce matter-geometry nonminimal coupling which is proportional to the gradient of quadratic curvature invariants. Those are mimicking the conformal trace anomaly when backreaction of the quantum fields to a curved spacetime geometry is considered. We consider a static spherically symmetric stellar structure with anisotropic fluid and Krori-Barua metric potentials model to examine the theory. Confronting the model with NICER+XMM-Newton observational constraints on the pulsar PSR J0740$+$6620 quantifies the amount of the nonminimal coupling via a dimensionless parameter $\epsilon \simeq -0.01$. We verify that the conformal symmetry is broken everywhere inside the pulsar as the trace anomaly $\Delta >0$, or equivalently the trace of the stress-energy tensor $\mathfrak{T}<0$, whereas the adiabatic sound speed does not violate the conjecture conformal upper limit $v_r^2/c^2=1/3$. The maximum compactness accordingly is $C_{\text{max}}=0.752$ which is $4\%$ higher than GR. Notably, if the conformal sound speed constraint is hold, observational data excludes $\epsilon \ge 0$ up to $\ge 1.6\sigma$. The stellar model is consistent with the self-bound structure with soft linear equation of state. Investigating possible connection with MIT bag model of strange quarks sets physical bounds from microscopic physics which confirm the negative value of the parameter $\epsilon$. We estimate a radius $R=13.21\pm 0.96$ km of the most massive observed compact star PSR J0952$-$0607 with $M=2.35\pm 0.17M_{\odot }$. Finally, we show that the corresponding mass-radius diagram fits well lowest-mass pulsar HESS J1731$-$347 and highest-mass pulsar PSR J0952$-$0607 ever observed as well as the intermediate mass range as obtained by NICER and LIGO/Virgo observations.

pdfLaTeX, 26 pages, 6 figures, 4 tables

References in corpus (31)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter
• GW190425: Observation of a Compact Binary Coalescence with Total Mass $\sim 3.4M_{\odot }$
• A NICER View of the Massive Pulsar PSR J0740+6620 Informed by Radio Timing and XMM-Newton Spectroscopy
• Refined Mass and Geometric Measurements of the High-Mass PSR J0740+6620
• PSR J0952-0607: The Fastest and Heaviest Known Galactic Neutron Star
• All static spherically symmetric anisotropic solutions of Einstein's equations
• Nonparametric constraints on neutron star matter with existing and upcoming gravitational wave and pulsar observations
• A NICER view of PSR J0030+0451: Implications for the dense matter equation of state
• Einstein and Rastall Theories of Gravitation in Comparison
• An updated mass-radius analysis of the 2017-2018 NICER data set of PSR J0030+0451
• Impact of the PSR J0740+6620 radius constraint on the properties of high-density matter
• On the Sound Speed in Neutron Stars
• Pulsars as Astrophysical Laboratories for Nuclear and Particle Physics
• Shearing Expansion-free Spherical Anisotropic Fluid Evolution
• Trace anomaly as signature of conformality in neutron stars
• Accelerated cosmos in a non-extensive setup
• Anisotropic Neutron Stars Modelling: Constraints in Krori-Barua Spacetime
• Constraining the equation of state of supra-nuclear dense matter from XMM-Newton observations of neutron stars in globular clusters
• Non-trivial class of anisotropic compact stellar model in Rastall gravity
• A light strange star in the remnant HESS J1731-347: minimal consistency checks
• Constraining the Rastall parameters in static spacetimes with galaxy-scale strong gravitational lensing
• Impact of large-mass constraints on the properties of neutron stars
• Impact of Rastall gravity on mass, radius and sound speed of the pulsar PSR J0740+6620
• Cosmic evolution of dark energy in a generalized Rastall gravity
• Structure Formation in Generalized Rastall Gravity
• Implications of the Conformal Constraint on Sound Speed on the Radius of PSR J0952-0607 within Rastall Gravity
• Rapidly rotating compact stars in Rastall's gravity
• Shadow, absorption and Hawking radiation of a Schwarzschild black hole surrounded by a cloud of strings in Rastall gravity

Cited by in corpus (3)

• Properties of the Object HESS J1731-347 as a Twin Compact Star
• Buchdahl limit of compact stars in presence of Weyl anomaly
• Modeling Gravastar Structure admitting Kuchowicz Spacetime in Rastall Gravity Theory