Distribution of the dark matter inner slope in massive ellipticals

Determine the statistical distribution of the inner slope parameter gamma_in of the generalized Navarro–Frenk–White dark matter density profile in massive elliptical galaxies that act as strong gravitational lenses, in order to reduce modeling systematics in time-delay cosmography.

Background

Time-delay cosmography is sensitive to the mass profile of lens galaxies, particularly to deviations from a pure power-law profile captured via the mass-sheet transform and parameters like the inner slope of the dark matter halo. The paper explores a generalized NFW (gNFW) parameterization and notes that different studies and simulations infer a wide range of inner slopes for massive ellipticals.

The authors emphasize that uncertainty in the distribution of the inner slope contributes to systematic uncertainties in strong-lensing analyses. Clarifying this distribution would help calibrate selection biases and improve the robustness of H0 inferences.