Rotation-curve residuals reveal a suppressed acceleration branch in dwarf galaxies

Rotation-curve residuals reveal a suppressed acceleration branch in dwarf galaxies
Hosik Lee
arXiv:2605.23302v2 Announce Type: replace
Abstract: Galaxy rotation curves exhibit systematic deviations from the Newtonian expectation inferred from visible matter alone. Existing phenomenological descriptions capture many aspects of these deviations, but a common residual structure across massive disks and dwarf irregular galaxies remains unclear. We investigate whether rotation-curve residuals organize into a simple empirical form across the SPARC and LITTLE THINGS samples. We analyze 175 SPARC galaxies and 22 LITTLE THINGS dwarf irregular galaxies in velocity-squared space after subtracting a leading Newtonian-like term. We fit a generalized residual family, v^2-A/r=B+Cr^{q+1}, and examine which radial scaling is selected by the data. The galaxy population systematically favors the limit (qsimeq0), corresponding to an approximately linear residual relation, (v^2-A/r=B+Cr). SPARC galaxies generally occupy a high-(B) branch, whereas LITTLE THINGS dwarf galaxies show suppressed residual intercepts, including several systems consistent with (B=0). For the SPARC sample, the high-(B) branch approximately follows (Bpropto M_{rm bar}^{0.72}). {Rotation-curve residuals are not featureless scatter beyond the leading Newtonian-like contribution, but instead show a simple population-dependent empirical organization across massive and dwarf galaxy systems.}arXiv:2605.23302v2 Announce Type: replace
Abstract: Galaxy rotation curves exhibit systematic deviations from the Newtonian expectation inferred from visible matter alone. Existing phenomenological descriptions capture many aspects of these deviations, but a common residual structure across massive disks and dwarf irregular galaxies remains unclear. We investigate whether rotation-curve residuals organize into a simple empirical form across the SPARC and LITTLE THINGS samples. We analyze 175 SPARC galaxies and 22 LITTLE THINGS dwarf irregular galaxies in velocity-squared space after subtracting a leading Newtonian-like term. We fit a generalized residual family, v^2-A/r=B+Cr^{q+1}, and examine which radial scaling is selected by the data. The galaxy population systematically favors the limit (qsimeq0), corresponding to an approximately linear residual relation, (v^2-A/r=B+Cr). SPARC galaxies generally occupy a high-(B) branch, whereas LITTLE THINGS dwarf galaxies show suppressed residual intercepts, including several systems consistent with (B=0). For the SPARC sample, the high-(B) branch approximately follows (Bpropto M_{rm bar}^{0.72}). {Rotation-curve residuals are not featureless scatter beyond the leading Newtonian-like contribution, but instead show a simple population-dependent empirical organization across massive and dwarf galaxy systems.}