Program Listing for File Redshift.cpp

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#include "crpropa/module/Redshift.h"
#include "crpropa/Units.h"
#include "crpropa/Cosmology.h"

#include <limits>

namespace crpropa {

void Redshift::process(Candidate *c) const {
        double z = c->getRedshift();

        // check if z = 0
        if (z <= std::numeric_limits<double>::min())
                return;

        // use small step approximation:  dz = H(z) / c * ds
        double dz = hubbleRate(z) / c_light * c->getCurrentStep();

        // prevent dz > z
        dz = std::min(dz, z);

        // update redshift
        c->setRedshift(z - dz);

        // adiabatic energy loss: dE / dz = E / (1 + z)
        double E = c->current.getEnergy();
        c->current.setEnergy(E * (1 - dz / (1 + z)));
}

std::string Redshift::getDescription() const {
        std::stringstream s;
        s << "Redshift: h0 = " << hubbleRate() / 1e5 * Mpc << ", omegaL = "
                        << omegaL() << ", omegaM = " << omegaM();
        return s.str();
}

void FutureRedshift::process(Candidate *c) const {
        double z = c->getRedshift();

        // check if z = -1
        if (z <= -1)
                return;

        // use small step approximation:  dz = H(z) / c * ds
        double dz = hubbleRate(z) / c_light * c->getCurrentStep();

        // update redshift
        c->setRedshift(z - dz);

        // adiabatic energy loss: dE / dz = E / (1 + z)
        double E = c->current.getEnergy();
        c->current.setEnergy(E * (1 - dz / (1 + z)));
}

std::string FutureRedshift::getDescription() const {
        std::stringstream s;
        s << "FutureRedshift: h0 = " << hubbleRate() / 1e5 * Mpc << ", omegaL = "
                        << omegaL() << ", omegaM = " << omegaM();
        return s.str();
}

} // namespace crpropa