Composition dependence of the torsional ordering

Investigate whether the ordering found for cold carbon white dwarfs in quadratic f(T)=T+Xi T^2 gravity—negative couplings producing larger masses and smaller radii, while positive couplings produce smaller masses and larger radii—persists for white dwarfs with other nuclear compositions.

Background

The paper computes static equilibrium sequences for cold carbon white dwarfs in covariant quadratic f(T)=T+Xi T^2 gravity, using a fixed equation of state that includes relativistic electron degeneracy, Coulomb lattice corrections, and the electron-capture density as the upper density limit. At fixed central density, negative values of Xi yield larger masses and smaller radii than general relativity, whereas positive values yield smaller masses and larger radii. The deviations grow toward higher density and are more pronounced in mass than in radius.

The authors explicitly identify testing other white-dwarf compositions as the first future research step. Such a comparison is needed to determine whether the reported structural ordering is a robust consequence of the torsional sector or instead depends on the carbon-specific microphysics, including composition-dependent mass density, equation-of-state behavior, and electron-capture thresholds.