Supermassive Neutron Stars in Axion $F(R)$ Gravity

Abstract

We investigated realistic neutron stars in axion $R^2$ gravity. The coupling between curvature and axion field $\varphi$ is assumed in the simple form $\sim R^2\varphi$. For the axion mass in the range $m_a\sim 10^{-11}-10^{-10}$ eV the solitonic core within neutron star and corresponding halo with size $\sim 100$ km can exist. Therefore the effective contribution of $R^2$ term grows inside the star and it leads to change of star parameters (namely, mass and radius). We obtained the increase of star mass independent from central density for wide range of masses. Therefore, maximal possible mass for given equation of state grows. At the same time, the star radius increases not so considerably in comparison with GR. {Hence, our model may predict possible existence of supermassive compact stars with masses $M\sim 2.2-2.3M_{\odot }$ and radii $R_s\sim 11$ km for realistic equation of state (we considered APR equation of state). In General Relativity one can obtain neutron stars with such characteristics only for unrealistic, extremely stiff equations of state.} Note that this increase of mass occurs due to change of solution for scalar curvature outside the star. In GR curvature drops to zero on star surface where $\rho =p=0$. In the model under consideration the scalar curvature dumps more slowly in comparison with vacuum $R^2$ gravity due to axion "galo" around the star.

arXiv commentto appear in MNRAS, 9pp., 6 figures

References in corpus (55)

• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• Unified cosmic history in modified gravity: from F(R) theory to Lorentz non-invariant models
• Type Ia Supernova Discoveries at z>1 From the Hubble Space Telescope: Evidence for Past Deceleration and Constraints on Dark Energy Evolution
• Extended Theories of Gravity
• Modified Gravity Theories on a Nutshell: Inflation, Bounce and Late-time Evolution
• A direct empirical proof of the existence of dark matter
• Is Cosmic Speed-Up Due to New Gravitational Physics?
• Modified gravity with negative and positive powers of the curvature: unification of the inflation and of the cosmic acceleration
• Axion Cosmology
• A NICER View of PSR J0030+0451: Millisecond Pulsar Parameter Estimation
• Curvature Quintessence
• Results from the Final Exposure of the CDMS II Experiment
• Palatini Approach to Modified Gravity: f(R) Theories and Beyond
• A Search for Invisible Axion Dark Matter with the Axion Dark Matter Experiment
• WIMP dark matter candidates and searches - current status and future prospects
• Direct Detection of WIMP Dark Matter: Concepts and Status
• Where new gravitational physics comes from: M-theory?
• Further stable neutron star models from f(R) gravity
• Black holes, cosmological solutions, future singularities, and their thermodynamical properties in modified gravity theories
• Hydrostatic equilibrium and stellar structure in f(R)-gravity
• Revealing the properties of dark matter in the merging cluster MACSJ0025.4-1222
• The Mass-Radius relation for Neutron Stars in $f(R)$ gravity
• Evidence for a Massive Neutron Star from a Radial-Velocity Study of the Companion to the Black Widow Pulsar PSR B1957+20
• First Results from ABRACADABRA-10 cm: A Search for Sub-$\mu$eV Axion Dark Matter
• Maximal neutron star mass and the resolution of hyperon puzzle in modified gravity
• What does the Bullet Cluster tell us about self-interacting dark matter?
• Tunable axion plasma haloscopes
• Constraints on Perturbative f(R) Gravity via Neutron Stars
• The realistic models of relativistic stars in f(R) = R + alpha R^2 gravity
• Physical parameters of the high-mass X-ray binary 4U1700-37
• Jeans analysis of self-gravitating systems in f(R)-gravity
• Chandra Spectra of the Soft X-ray Diffuse Background
• A New Bound on Axion-Like Particles
• The large-scale modulation of the density distribution in standard axionic CDM and its cosmological and physical impact
• Detecting Axion Dark Matter with Radio Lines from Neutron Star Populations
• Unification of Inflation with Dark Energy in $f(R)$ Gravity and Axion Dark Matter
• Magnetic Neutron Stars in f(R) gravity
• Detecting the Stimulated Decay of Axions at Radio Frequencies
• Modified gravity with logarithmic curvature corrections and the structure of relativistic stars
• Looking for Axion Dark Matter in Dwarf Spheroidals
• The mass-radius relation for neutron stars in $f(R)=R+\alpha R^2$ gravity: a comparison between purely metric and torsion formulations
• Non-minimal coupling of photons and axions
• Numerical solutions of the modified Lane-Emden equation in f(R)-gravity
• Neutron stars in a perturbative $f(R)$ gravity model with strong magnetic fields
• Quantifying the evidence for Dark Matter in CoGeNT data
• The Past and Future of Light Dark Matter Direct Detection
• Efficient self-resonance instability from axions
• Geometrical Destabilisation of Ultra-Light Axions in String Inflation
• An introduction to the theory of rotating relativistic stars
• Gradient models of the axion-photon coupling
• The Classical Stability Of The Ghost Condensate
• Axion-induced oscillations of cooperative electric field in a cosmic magneto-active plasma
• Radiative Axion Inflation
• Axion Detection via Atomic Excitations

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