Feature Request: Implement Yang et al. 2024 SIDM Profile as Default for Subhalos and LOS Halos

[mwiet]

Description

Implementation of a single closed-form parametric profile from Yang, Nadler, Yu & Zhong (2024) that spans the entire gravothermal sequence. This should become the default SIDM cored/core-collapsed path for lens-plane subhalos and line-of-sight (LOS) halos, moving the existing Kaplinghat profile to a legacy status.

Proposed Implementation Details

1. Profile Hierarchy & Default Status:

   • Default: Make the Yang+ 2024 profile the primary, default SIDM path for modeling.
   • Legacy: Retain the Kaplinghat framework strictly as a legacy option for backward compatibility.

2. Physical Collapse-Time Solve (τ formulation):

   • Implement the per-halo dimensionless evolution time τ = t / t_c.
   • Calculate the collapse time t_c from the physical parameters at the halo's CDM baseline (ρ_s, r_s):
     t_c = (150 / C) / [ (σ_eff / m) * ρ_s * r_s * √(4πG * ρ_s) ]
     (where C = 0.75).
   • Use a per-plane t_age to compute t (so τ updates properly dynamically depending on the redshift plane of the halo/subhalo).

3. Velocity Dependence (Outmezguine+ 2023):

   • Velocity dependence is explicitly in scope.
   • σ_eff must be computed dynamically using a velocity-dependent cross-section: σ ∝ v^{-a}, parameterized by a (following Outmezguine+ 2023).

References

To assist with the implementation and physical constants, refer to the following literature:

• Yang+ 2024 (arXiv:2305.16176): The primary profile parameterization, including τ and t_c formulations.
• Rocha+ 2013 (arXiv:1208.3025): Core baseline SIDM scaling properties.
• Outmezguine+ 2023 (arXiv:2204.06568): Universal gravothermal sequence and the formulation for σ_eff / velocity dependence.
• Phoroutan-Mehr & Yu 2025 (arXiv:2411.18751): Advanced implementation of σ ∝ v^{-a} (includes an optional spike feature, which should be off by default).
• Yang+ 2025 (arXiv:2406.10753): Validation of the gravothermal profile.
• Raut+ 2026 (arXiv:2604.22013): Extended τ-model (should be integrated as an optional plug-in).
• Ando+ 2024 (arXiv:2403.16633): Population τ mapping used for the diagnostic f_cc cross-check.
• Minor+ 2021 / SHARP IX 2025 (arXiv:2011.10627 / arXiv:2505.07944): The J0946 collapse target data for integration tests and empirical validation.