Newtonian I-Love-Q relations: An enthalpy-based approach

@misc{kunjipurayil2026newtonian,
  title = {{Newtonian I-Love-Q relations: An enthalpy-based approach}},
  author = {Athul Kunjipurayil and J. Piekarewicz},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.31730},
  eprint = {2610.31730},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.31730},
}

TY  - UNPB
TI  - Newtonian I-Love-Q relations: An enthalpy-based approach
AU  - Athul Kunjipurayil
AU  - J. Piekarewicz
PY  - 2026
DA  - 2026/10/22
PB  - arXiv
DO  - 10.48550/arxiv.2610.31730
UR  - https://arxiv.org/abs/2610.31730
AB  - We present a pedagogical introduction to the I-Love-Q relations within Newtonian gravity using an enthalpy-based formulation of stellar structure. Introducing the specific enthalpy converts Euler's equation into a first integral of hydrostatic equilibrium and recasts the equation of state as a relation between the mass density and the enthalpy. Together with Poisson's equation, these relations provide a unified description of spherical equilibrium and deformations induced by rotation and tides. We illustrate the formalism with polytropic equations of state and a relativistic free Fermi gas. In Newtonian gravity, slow uniform rotation and a weak tidal field excite the same linear quadrupolar response, yielding the exact identity I̅^ 2Q̅/λ̅≡1 for the dimensionless (``bar'') observables---independently of the equation of state. This exact identity is distinguished from the approximate universality of the pairwise I-Love-Q relations, whose residual dependence on stellar structure is illustrated by the models considered in this work.
ER  -