ultra_relativistic.h

#pragma once
 
#include <string_view>
 
#include "base_species.h"
#include "species_build_context.h"
 
struct background;
 
class UltraRelativisticSpecies : public BaseSpecies {
 public:
  static constexpr std::string_view kTypeName = "ur";
 
  UltraRelativisticSpecies(const background& pba, double omega0_ur);
 
  double GetOmega0() const override {
    return Omega0_ur_;
  }
 
  double GetRadiationOmega0() const override {
    return Omega0_ur_;
  }
 
  // ── Background ─────────────────────────────────────────────────────────────
  void RegisterBackgroundIndices(int& index_bg) override;
  void ComputeBackground(double a, const double* pvecback_B, double* pvecback) override;
  double Rho(const double* pvecback) const override;
  double P(const double* pvecback) const override;
  double PPrime(double a,
                double H,
                const double* pvecback_B,
                const double* pvecback) const override;
 
  bool IsFreestreaming() const override {
    return true;
  }
  void WriteBackgroundColumnTitles(BackgroundColumnWriter& w) const override;
  void WriteBackgroundData(const double* pvecback, BackgroundColumnWriter& w) const override;
 
  // ── Perturbations ──────────────────────────────────────────────────────────
 
  void RegisterTransferSourceIndices(int& index_tp, const SourceRequestContext& ctx) override;
 
  struct PerturbLayout : BaseSpecies::PerturbLayout {
    int idx_delta = -1;  
    int idx_theta = -1;  
    int idx_shear = -1;  
    int idx_l3    = -1;  
    int l_max     = -1;  
  };
 
  std::unique_ptr<BaseSpecies::PerturbLayout> CreatePerturbLayout() const override {
    return std::make_unique<PerturbLayout>();
  }
 
  void RegisterPerturbationIndices(BaseSpecies::PerturbLayout& layout,
                                   perturb_vector* pv,
                                   const precision* ppr,
                                   int& index_pt,
                                   const perturb_workspace* ppw,
                                   int gauge) override;
  void PerturbDerivs(const BaseSpecies::PerturbLayout& layout,
                     double tau,
                     const double* y,
                     double* dy,
                     const perturb_parameters_and_workspace& ppaw) const override;
 
  StressEnergyContribution StressEnergy(const BaseSpecies::PerturbLayout& layout,
                                        const perturb_vector* pv,
                                        const double* y,
                                        const double* pvecback,
                                        const perturb_workspace* ppw) const override;
 
  void FillSources(const BaseSpecies::PerturbLayout& layout,
                   const double* y,
                   const double* dy,
                   PerturbSourceContext& ctx) const override;
 
  void ApplyInitialConditions(const BaseSpecies::PerturbLayout& layout,
                              double* y,
                              const PerturbIcContext& ctx) override;
 
  void PerturbSynchronousToNewtonian(const BaseSpecies::PerturbLayout& layout,
                                     double* y,
                                     const PerturbIcContext& ctx) override;
 
  void MarkUsedInSources(const BaseSpecies::PerturbLayout& layout,
                         const perturb_workspace* ppw,
                         int* used_in_sources) const override;
 
  void CopyPerturbationsAcrossSwitch(const BaseSpecies::PerturbLayout& old_layout,
                                     const BaseSpecies::PerturbLayout& new_layout,
                                     const double* old_y,
                                     double* new_y,
                                     const PerturbSwitchContext& ctx) const override;
 
  // ── Tensor mode ────────────────────────────────────────────────────────────
  //
  // The tensor "relativistic neutrino" hierarchy is NOT a UR-species concern: it
  // is a single hierarchy sourced by the gravitational waves and shared by ur and
  // massless-approximated ncdm. perturb_vector owns it (pv->tensor_ur_layout) and
  // the perturbations module registers/evolves it directly, so URSpecies has no
  // tensor index-registration or tensor-derivs overrides.
 
  static std::vector<Named> CreateAll(const SpeciesBuildContext& ctx);
 
  void WriteOutputColumns(
      PerturbColumnWriter& writer,
      const PerturbationsModule& mod,
      file_format fmt,
      TransferColumnSection section = TransferColumnSection::all) const override;
  void PrintVariables(PerturbColumnWriter& writer,
                      double tau,
                      const double* y,
                      const PerturbationsModule& mod,
                      const perturb_workspace* ppw) const override;
 
 private:
  double Omega0_ur_;
  double H0_;
 
  int index_tp_delta_ = -1;  // #309 transfer-source slot
  int index_tp_theta_ = -1;
};