Constraining Quadratic $f(R)$ Gravity from Astrophysical Observations of the Pulsar J0704+6620

Abstract

We apply quadratic $f(R)=R+\epsilon R^2$ field equations, where $\epsilon$ has a dimension [L${}^2$], to static spherical stellar model. We assume the interior configuration is determined by Krori-Barua ansatz and additionally the fluid is anisotropic. Using the astrophysical measurements of the pulsar PSR J0740+6620 as inferred by NICER and XMM observations, we determine $\epsilon \approx \pm 3$ km${}^2$. We show that the model can provide a stable configuration of the pulsar PSR J0740+6620 in both geometrical and physical sectors. We show that the Krori-Barua ansatz within $f(R)$ quadratic gravity provides semi-analytical relations between radial, $p_r$, and tangential, $p_t$, pressures and density $\rho$ which can be expressed as $p_r\approx v_r^2(\rho -{\rho }_1)$ and $p_r\approx v_t^2(\rho -{\rho }_2)$, where $v_r$ ($v_t$) is the sound speed in radial (tangential) direction, ${\rho }_1={\rho }_s$ (surface density) and ${\rho }_2$ are completely determined in terms of the model parameters. These relations are in agreement with the best-fit equations of state as obtained in the present study. We further put the upper limit on the compactness, which satisfies the $f(R)$ modified Buchdahl limit. Interestingly, the quadratic $f(R)$ gravity with negative $\epsilon$ naturally restricts the maximum compactness to values lower than Buchdahl limit, unlike the GR or $f(R)$ gravity with positive $\epsilon$ where the compactness can arbitrarily approach the black hole limit $C\to 1$. The model predicts a core density a few times the saturation nuclear density ${\rho }_{\text{nuc}}=2.7\times 10^{14}$ g/cm${}^3$, and a surface density ${\rho }_s>{\rho }_{\text{nuc}}$. We provide the mass-radius diagram corresponding to the obtained boundary density which has been shown to be in agreement with other observations.

18 pages, 9 figures and one table

References in corpus (71)

• Observation of Gravitational Waves from a Binary Black Hole Merger
• Unified cosmic history in modified gravity: from F(R) theory to Lorentz non-invariant models
• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• f(R) theories
• Modified Gravity Theories on a Nutshell: Inflation, Bounce and Late-time Evolution
• GW170817: Measurements of Neutron Star Radii and Equation of State
• GW190814: Gravitational Waves from the Coalescence of a 23 M${}_{\odot }$ Black Hole with a 2.6 M${}_{\odot }$ Compact Object
• 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 $\sim 3.4M_{\odot }$
• Relativistic Shapiro delay measurements of an extremely massive millisecond pulsar
• Masses, Radii, and Equation of State of Neutron Stars
• 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
• Testing the nature of dark compact objects: a status report
• Binary Black Hole Population Properties Inferred from the First and Second Observing Runs of Advanced LIGO and Advanced Virgo
• Evidence for quark-matter cores in massive neutron stars
• The NANOGrav Nine-year Data Set: Mass and Geometric Measurements of Binary Millisecond Pulsars
• PSR J0952-0607: The Fastest and Heaviest Known Galactic Neutron Star
• Maximum bounds on the surface redshift of anisotropic stars
• Testing General Relativity with Pulsar Timing
• The NANOGrav 11-year Data Set: Pulsar-timing Constraints On The Stochastic Gravitational-wave Background
• Further stable neutron star models from f(R) gravity
• Bounds on the basic physical parameters for anisotropic compact general relativistic objects
• Nonparametric constraints on neutron star matter with existing and upcoming gravitational wave and pulsar observations
• Sound velocity bound and neutron stars
• Hydrostatic equilibrium and stellar structure in f(R)-gravity
• Stellar equilibrium configurations of compact stars in $f(R,T)$ gravity
• Extreme neutron stars from Extended Theories of Gravity
• A NICER view of PSR J0030+0451: Implications for the dense matter equation of state
• Electrically charged compact stars and formation of charged black holes
• Maximal neutron star mass and the resolution of hyperon puzzle in modified gravity
• Constraints on Perturbative f(R) Gravity via Neutron Stars
• Impact of the PSR J0740+6620 radius constraint on the properties of high-density matter
• Relativistic stars in f(R) gravity, and absence thereof
• The realistic models of relativistic stars in f(R) = R + alpha R^2 gravity
• Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. I. The Millisecond Pulsar X-ray Data Set
• Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. II. Emission from Hot Spots on a Rapidly Rotating Neutron Star
• Slowly rotating neutron and strange stars in $R^2$ gravity
• Non-perturbative and self-consistent models of neutron stars in R-squared gravity
• Anisotropic stars as ultracompact objects in General Relativity
• On neutron stars in f(R) theories: small radii, large masses and large energy emitted in a merger
• Neutron stars in Starobinsky model
• Polarizations of gravitational waves in $f(R)$ gravity
• The existence of relativistic stars in f(R) gravity
• Anisotropic Neutron Stars Modelling: Constraints in Krori-Barua Spacetime
• Magnetic Neutron Stars in f(R) gravity
• Rapidly rotating neutron stars in $R$-squared gravity
• Stable and self-consistent compact star models in teleparallel gravity
• Non-trivial class of anisotropic compact stellar model in Rastall gravity
• Relativistic Stars in dRGT Massive Gravity
• Black Hole Formation in the Lower Mass Gap through Mergers and Accretion in AGN Disks
• A new f(R) Gravity Model and properties of Gravitational Waves in it
• Neutron star radius measurement from the ultraviolet and soft X-ray thermal emission of PSR J0437-4715
• Fast spinning strange stars: possible ways to constrain interacting quark matter parameters
• The effect of $f(R,T)$ modified gravity on mass and radius of pulsar HerX1
• Buchdahl-Bondi limit in modified gravity: Packing extra effective mass in relativistic compact stars
• The Polarizations of Gravitational Waves
• On the maximum mass limit of neutron stars in scalar-tensor gravity
• Impact of Rastall gravity on mass, radius and sound speed of the pulsar PSR J0740+6620
• Tolman-Oppenheimer-Volkoff equations in non-local $f(R)$ gravity
• Compactness bounds in General Relativity
• Equilibrium and stability of relativistic stars in extended theories of gravity
• Dilatonic Equation of Hydrostatic Equilibrium and Neutron Star Structure
• Implications of the Conformal Constraint on Sound Speed on the Radius of PSR J0952-0607 within Rastall Gravity
• Structure of Compact Stars in R-squared Palatini Gravity
• Equation of State of Neutron Stars with Junction Conditions in the Starobinsky Model
• Relativistic stars in Starobinsky gravity with the matched asymptotic expansions method
• Scalar polarization window in gravitational-wave signals
• Tests of gravitational scalar polarization and constraints of chameleon $f(R)$ gravity from comprehensive analysis of binary pulsars
• A realistic model of a neutron star in minimal dilatonic gravity

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