Semi-Analytic Stellar Structure in Scalar-Tensor Gravity

C.P. Burgess; M.W. Horbatsch

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Semi-Analytic Stellar Structure in Scalar-Tensor Gravity

M.W. Horbatsch, C.P. Burgess

General Relativity and Quantum Cosmology · Submitted 23 Jun 2010

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim The four observable parameters that characterize the fields external to a spherically symmetric star (the stellar radius, R, mass, M, scalar `charge', Q, and the scalar's asymptotic value, phi_infty) are subject to two relations because of the matching to the interior solution, generalizing the usual mass-radius, M(R), relation of General Relativity.

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What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.22 · human participants 0.01 · controlled comparison 0.14 · randomized assignment 0.01 · states quantitative result 0.07 · compares with prior results 0.92 · mentions code or data availability 0.02.

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Precision tests of gravity can be used to constrain the properties of hypothetical very light scalar fields, but these tests depend crucially on how macroscopic astrophysical objects couple to the new scalar field. We develop quasi-analytic methods for solving the equations of stellar structure using scalar-tensor gravity, with the goal of seeing how stellar properties depend on assumptions made about the scalar coupling at a microscopic level. We illustrate these methods by applying them to Brans-Dicke scalars, and their generalization in which the scalar-matter coupling is a weak function of the scalar field. The four observable parameters that characterize the fields external to a spherically symmetric star (the stellar radius, R, mass, M, scalar `charge', Q, and the scalar's asymptotic value, phi_infty) are subject to two relations because of the matching to the interior solution, generalizing the usual mass-radius, M(R), relation of General Relativity. We identify how these relations depend on the microscopic scalar couplings, agreeing with earlier workers when comparisons are possible. Explicit analytical solutions are obtained for the instructive toy model of constant-density stars, whose properties we compare to more realistic equations of state for neutron star models.

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What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	Precision tests of gravity can be used to constrain the properties of hypothetical very light scalar fields, but these tests depend crucially on how macroscopic astrophysical objects couple to the new scalar field.	background 1.00	0.06	0.05	asserted 0.97
s1	We develop quasi-analytic methods for solving the equations of stellar structure using scalar-tensor gravity, with the goal of seeing how stellar properties depend on assumptions made about the scalar coupling at a microscopic level.	contribution 0.83	0.95	0.09	asserted 0.97
s2	We illustrate these methods by applying them to Brans-Dicke scalars, and their generalization in which the scalar-matter coupling is a weak function of the scalar field.	method 0.56	0.87	0.05	asserted 0.99
s3	The four observable parameters that characterize the fields external to a spherically symmetric star (the stellar radius, R, mass, M, scalar `charge', Q, and the scalar's asymptotic value, phi_infty) are subject to two relations because of the matching to the interior solution, generalizing the usual mass-radius, M(R), relation of General Relativity.	result 0.90	0.69	0.31	asserted 1.00
s4	We identify how these relations depend on the microscopic scalar couplings, agreeing with earlier workers when comparisons are possible.	result 0.76	0.89	0.20	asserted 1.00
s5	Explicit analytical solutions are obtained for the instructive toy model of constant-density stars, whose properties we compare to more realistic equations of state for neutron star models.	contribution 0.44	0.95	0.14	asserted 1.00

What kind of paper the classifier reports this is: method or tool 0.66 · evidence from proof or derivation 1.00.

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Original abstract

Precision tests of gravity can be used to constrain the properties of hypothetical very light scalar fields, but these tests depend crucially on how macroscopic astrophysical objects couple to the new scalar field. We develop quasi-analytic methods for solving the equations of stellar structure using scalar-tensor gravity, with the goal of seeing how stellar properties depend on assumptions made about the scalar coupling at a microscopic level. We illustrate these methods by applying them to Brans-Dicke scalars, and their generalization in which the scalar-matter coupling is a weak function of the scalar field. The four observable parameters that characterize the fields external to a spherically symmetric star (the stellar radius, R, mass, M, scalar `charge', Q, and the scalar's asymptotic value, phi_infty) are subject to two relations because of the matching to the interior solution, generalizing the usual mass-radius, M(R), relation of General Relativity. We identify how these relations depend on the microscopic scalar couplings, agreeing with earlier workers when comparisons are possible. Explicit analytical solutions are obtained for the instructive toy model of constant-density stars, whose properties we compare to more realistic equations of state for neutron star models.

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References

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Cited by 9 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

Exact Solution of the Non-minimally Coupled Klein-Gordon Equation in the Schwarzschild Star
gr-qc 2026-06 unverdicted novelty 6.0 of 10

Exact solution of non-minimally coupled massive Klein-Gordon equation in Schwarzschild star metric expressed via general Heun function after geometry-induced coordinate transformation.
Slowly Rotating Anisotropic Neutron Stars in General Relativity and Scalar-Tensor Theory
gr-qc 2014-11 accept novelty 6.0 of 10

Anisotropic pressure in neutron-star cores changes the moment of inertia and lowers the critical scalar-tensor coupling needed for spontaneous scalarization, so binary pulsar data could in principle constrain core anisotropy.
Cosmic Black-Hole Hair Growth and Quasar OJ287
gr-qc 2011-11 conditional novelty 6.0 of 10

The absence of extra dipole radiation in the OJ287 black hole binary bounds the instantaneous time variation of any light scalar field at redshift 0.306 to |mu| < (16 days)^-1, independent of how the scalar couples to matter.
Compact stars in alternative theories of gravity. Einstein-Dilaton-Gauss-Bonnet gravity
gr-qc 2011-09 conditional novelty 6.0 of 10

Neutron stars in Einstein-Dilaton-Gauss-Bonnet gravity cease to exist above a critical coupling, and observed high-mass neutron stars bound that coupling more tightly than stellar-mass black holes do.
Parameterized Post-Einsteinian Gravitational Waveforms in Various Modified Theories of Gravity
gr-qc 2018-09 accept novelty 5.0 of 10

The authors derive parameterized corrections to gravitational-wave amplitude and phase in six modified gravity theories and in varying-G theories, extending prior work that focused on phase corrections only.

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The alternative scalar field dark sector of the Universe: Cosmological inflation, quintessence and ekpyrotic model in the framework of scalar-tensor cosmology
gr-qc 2026-09 conditional novelty 2.0 of 10

A doctoral dissertation synthesizing scalar-tensor, inflationary EFT, quintessence, and ekpyrotic and cyclic cosmology into a single scalar-field framing of the dark sector, built largely from prior published work.
Stellar structure models in modified theories of gravity: lessons and challenges
gr-qc 2019-12 accept novelty 2.0 of 10

The review maps how modified gravity changes stellar structure equations and summarizes the resulting constraints from neutron stars and dwarf stars.
Universal Relations and Alternative Gravity Theories
gr-qc 2017-09 conditional novelty 2.0 of 10

Universal relations among neutron star observables (I-Love-Q, higher multipole moments, oscillation frequencies) survive in most alternative theories of gravity, which limits their power to discriminate between theories.
Gravitational Wave Tests of General Relativity with Ground-Based Detectors and Pulsar Timing Arrays
gr-qc 2013-04 conditional novelty 2.0 of 10

Gravitational wave observations of compact binary mergers and pulsar timing can constrain alternatives to general relativity in the strong-field, dynamical regime, and the review catalogues the projected bound for eac...

How the literature uses it

20 arXiv papers cite this in 37 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 26 sentences without a confident label

Uses its method or tool 1 paper

Using the aforementioned algebraic coordinate transformation as in Ref. [ref] ,

Exact Solution of the Non-minimally Coupled Klein-Gordon Equation in the Schwarzschild Star · General Heun mapping · 1.00

Compares with it 1 paper

We see that scalarized stellar configurations in our model are energetically favorable, as happens in the case of purely conformal coupling theory [ref] .

Relativistic stars in scalar-tensor theories with disformal coupling · Stability of the solutions · 0.82

Cites it as background 9 papers

How to break this degeneracy is a longstanding problem to which many recent studies have been devoted: see, e.g., [ref] .

Impact of the equation-of-state -- gravity degeneracy on constraining the nuclear symmetry energy from astrophysical observables · Introduction · 0.94
One way to define the (ADM) mass [ref] , $M$, and the `scalar charge' [ref] , $Q$, is through the large-$r$ asymptotic form of the metric and the scalar field[Notice our conventions here for $Q$ follow those of ref.

Cosmic Black-Hole Hair Growth and Quasar OJ287 · Masses and scalar hair · 0.85
Structure of neutron stars in the presence of scalar-tensor fields had been investigated in Refs. [ref] , including the rotating case [ref] .

Neutron Star Structure in the Presence of Nonminimally Coupled Scalar Fields · INTRODUCTION · 0.99

What it cites · 22 sentences without a confident label

Uses the method or tool of 1 paper

We here instead follow [ref] and perform a simplified analysis.

Stability Analysis of Spherically Symmetric Star in Scalar-Tensor Theories of Gravity · Stability · 0.98

Uses data or values from 1 paper

Constraints on these PPN parameters from solar system observations provide the best bounds on the model, with $|γ̃-1|< 2.3 ×10^-5$ inferred from Cassini tracking, and $|β̃-1| < 2.3 ×10^-4$ from lunar laser ranging [ref] .

The Confrontation between General Relativity and Experiment · Observational constraints · 0.98

Cites as background 16 papers

See Appendix B of [ref] for a related discussion.

Testing gravity to second post-Newtonian order: a field-theory approach · Exterior solutions · 0.98
The equations of hydrostatic equilibrium in scalar-tensor gravity were first studied in [ref] , and subsequently in [ref] .

Interior perfect fluid scalar-tensor solution · Equations of hydrostatic equilibrium · 0.99
The equations of hydrostatic equilibrium in scalar-tensor gravity were first studied in [ref] , and subsequently in [ref] .

Spontaneous Scalarization and Boson Stars · Equations of hydrostatic equilibrium · 0.99

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