mirror of
https://github.com/cosmo-sims/MUSIC.git
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218 lines
7.8 KiB
C++
218 lines
7.8 KiB
C++
/*
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transfer_eisenstein.cc - This file is part of MUSIC -
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a code to generate multi-scale initial conditions
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for cosmological simulations
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Copyright (C) 2010 Oliver Hahn
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "transfer_function.hh"
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//! Implementation of abstract base class TransferFunction for the Eisenstein & Hu transfer function
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/*!
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This class implements the analytical fit to the matter transfer
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function by Eisenstein & Hu (1999). In fact it is their code.
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*/
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class transfer_eisenstein_plugin : public transfer_function_plugin
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{
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protected:
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using transfer_function_plugin::cosmo_;
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//Cosmology m_Cosmology;
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double m_h0;
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double omhh, /* Omega_matter*h^2 */
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obhh, /* Omega_baryon*h^2 */
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theta_cmb, /* Tcmb in units of 2.7 K */
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z_equality, /* Redshift of matter-radiation equality, really 1+z */
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k_equality, /* Scale of equality, in Mpc^-1 */
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z_drag, /* Redshift of drag epoch */
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R_drag, /* Photon-baryon ratio at drag epoch */
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R_equality, /* Photon-baryon ratio at equality epoch */
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sound_horizon, /* Sound horizon at drag epoch, in Mpc */
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k_silk, /* Silk damping scale, in Mpc^-1 */
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alpha_c, /* CDM suppression */
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beta_c, /* CDM log shift */
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alpha_b, /* Baryon suppression */
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beta_b, /* Baryon envelope shift */
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beta_node, /* Sound horizon shift */
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k_peak, /* Fit to wavenumber of first peak, in Mpc^-1 */
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sound_horizon_fit, /* Fit to sound horizon, in Mpc */
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alpha_gamma; /* Gamma suppression in approximate TF */
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//! private member function: sets internal quantities for Eisenstein & Hu fitting
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void TFset_parameters(double omega0hh, double f_baryon, double Tcmb)
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/* Set all the scalars quantities for Eisenstein & Hu 1997 fitting formula */
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/* Input: omega0hh -- The density of CDM and baryons, in units of critical dens,
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multiplied by the square of the Hubble constant, in units
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of 100 km/s/Mpc */
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/* f_baryon -- The fraction of baryons to CDM */
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/* Tcmb -- The temperature of the CMB in Kelvin. Tcmb<=0 forces use
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of the COBE value of 2.728 K. */
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/* Output: Nothing, but set many global variables used in TFfit_onek().
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You can access them yourself, if you want. */
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/* Note: Units are always Mpc, never h^-1 Mpc. */
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{
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double z_drag_b1, z_drag_b2;
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double alpha_c_a1, alpha_c_a2, beta_c_b1, beta_c_b2, alpha_b_G, y;
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if (f_baryon<=0.0 || omega0hh<=0.0) {
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fprintf(stderr, "TFset_parameters(): Illegal input.\n");
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exit(1);
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}
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omhh = omega0hh;
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obhh = omhh*f_baryon;
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if (Tcmb<=0.0) Tcmb=2.728; /* COBE FIRAS */
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theta_cmb = Tcmb/2.7;
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z_equality = 2.50e4*omhh/POW4(theta_cmb); /* Really 1+z */
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k_equality = 0.0746*omhh/SQR(theta_cmb);
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z_drag_b1 = 0.313*pow((double)omhh,-0.419)*(1+0.607*pow((double)omhh,0.674));
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z_drag_b2 = 0.238*pow((double)omhh,0.223);
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z_drag = 1291*pow(omhh,0.251)/(1+0.659*pow((double)omhh,0.828))*
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(1+z_drag_b1*pow((double)obhh,(double)z_drag_b2));
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R_drag = 31.5*obhh/POW4(theta_cmb)*(1000/(1+z_drag));
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R_equality = 31.5*obhh/POW4(theta_cmb)*(1000/z_equality);
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sound_horizon = 2./3./k_equality*sqrt(6./R_equality)*
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log((sqrt(1+R_drag)+sqrt(R_drag+R_equality))/(1+sqrt(R_equality)));
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k_silk = 1.6*pow((double)obhh,0.52)*pow((double)omhh,0.73)*(1+pow((double)10.4*omhh,-0.95));
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alpha_c_a1 = pow((double)46.9*omhh,0.670)*(1+pow(32.1*omhh,-0.532));
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alpha_c_a2 = pow((double)12.0*omhh,0.424)*(1+pow(45.0*omhh,-0.582));
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alpha_c = pow(alpha_c_a1,-f_baryon)*
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pow(alpha_c_a2,-CUBE(f_baryon));
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beta_c_b1 = 0.944/(1+pow(458*omhh,-0.708));
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beta_c_b2 = pow(0.395*omhh, -0.0266);
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beta_c = 1.0/(1+beta_c_b1*(pow(1-f_baryon, beta_c_b2)-1));
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y = z_equality/(1+z_drag);
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alpha_b_G = y*(-6.*sqrt(1+y)+(2.+3.*y)*log((sqrt(1+y)+1)/(sqrt(1+y)-1)));
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alpha_b = 2.07*k_equality*sound_horizon*pow(1+R_drag,-0.75)*alpha_b_G;
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beta_node = 8.41*pow(omhh, 0.435);
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beta_b = 0.5+f_baryon+(3.-2.*f_baryon)*sqrt(pow(17.2*omhh,2.0)+1);
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k_peak = 2.5*3.14159*(1+0.217*omhh)/sound_horizon;
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sound_horizon_fit = 44.5*log(9.83/omhh)/sqrt(1+10.0*pow(obhh,0.75));
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alpha_gamma = 1-0.328*log(431.0*omhh)*f_baryon + 0.38*log(22.3*omhh)*
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SQR(f_baryon);
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return;
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}
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//! private member function: computes transfer function for mode k (k in Mpc)
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inline double TFfit_onek(double k, double *tf_baryon, double *tf_cdm)
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/* Input: k -- Wavenumber at which to calculate transfer function, in Mpc^-1.
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*tf_baryon, *tf_cdm -- Input value not used; replaced on output if
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the input was not NULL. */
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/* Output: Returns the value of the full transfer function fitting formula.
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This is the form given in Section 3 of Eisenstein & Hu (1997).
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*tf_baryon -- The baryonic contribution to the full fit.
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*tf_cdm -- The CDM contribution to the full fit. */
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/* Notes: Units are Mpc, not h^-1 Mpc. */
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{
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double T_c_ln_beta, T_c_ln_nobeta, T_c_C_alpha, T_c_C_noalpha;
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double q, xx, xx_tilde;//, q_eff;
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double T_c_f, T_c, s_tilde, T_b_T0, T_b, f_baryon, T_full;
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//double T_0_L0, T_0_C0, T_0, gamma_eff;
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//double T_nowiggles_L0, T_nowiggles_C0, T_nowiggles;
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k = fabs(k); /* Just define negative k as positive */
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if (k==0.0) {
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if (tf_baryon!=NULL) *tf_baryon = 1.0;
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if (tf_cdm!=NULL) *tf_cdm = 1.0;
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return 1.0;
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}
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q = k/13.41/k_equality;
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xx = k*sound_horizon;
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T_c_ln_beta = log(2.718282+1.8*beta_c*q);
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T_c_ln_nobeta = log(2.718282+1.8*q);
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T_c_C_alpha = 14.2/alpha_c + 386.0/(1+69.9*pow(q,1.08));
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T_c_C_noalpha = 14.2 + 386.0/(1+69.9*pow(q,1.08));
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T_c_f = 1.0/(1.0+POW4(xx/5.4));
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T_c = T_c_f*T_c_ln_beta/(T_c_ln_beta+T_c_C_noalpha*SQR(q)) +
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(1-T_c_f)*T_c_ln_beta/(T_c_ln_beta+T_c_C_alpha*SQR(q));
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s_tilde = sound_horizon*pow(1+CUBE(beta_node/xx),-1./3.);
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xx_tilde = k*s_tilde;
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T_b_T0 = T_c_ln_nobeta/(T_c_ln_nobeta+T_c_C_noalpha*SQR(q));
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T_b = sin(xx_tilde)/(xx_tilde)*(T_b_T0/(1+SQR(xx/5.2))+
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alpha_b/(1+CUBE(beta_b/xx))*exp(-pow(k/k_silk,1.4)));
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f_baryon = obhh/omhh;
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T_full = f_baryon*T_b + (1-f_baryon)*T_c;
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/* Now to store these transfer functions */
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if (tf_baryon!=NULL) *tf_baryon = T_b;
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if (tf_cdm!=NULL) *tf_cdm = T_c;
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return T_full;
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}
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public:
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//! Constructor for Eisenstein & Hu fitting for transfer function
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/*!
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\param aCosm structure of type Cosmology carrying the cosmological parameters
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\param Tcmb mean temperature of the CMB fluctuations (defaults to
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Tcmb = 2.726 if not specified)
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*/
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transfer_eisenstein_plugin( config_file &cf )//Cosmology aCosm, double Tcmb = 2.726 )
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: transfer_function_plugin(cf), m_h0( cosmo_.H0*0.01 )
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{
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double Tcmb = pcf_->getValueSafe("cosmology","Tcmb",2.726);
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TFset_parameters( (cosmo_.Omega_m)*cosmo_.H0*cosmo_.H0*(0.01*0.01),
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cosmo_.Omega_b/(cosmo_.Omega_m-cosmo_.Omega_b),//-aCosm.Omega_b),
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Tcmb);
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tf_distinct_ = false;
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}
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//! Computes the transfer function for k in Mpc/h by calling TFfit_onek
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inline double compute( double k, tf_type type ){
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double tfb, tfcdm, fb, fc; //, tfull
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TFfit_onek( k*m_h0, &tfb, &tfcdm );
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fb = cosmo_.Omega_b/(cosmo_.Omega_m);
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fc = (cosmo_.Omega_m-cosmo_.Omega_b)/(cosmo_.Omega_m) ;
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return fb*tfb+fc*tfcdm;
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//return 1.0;
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}
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inline double get_kmin( void ){
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return 1e-4;
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}
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inline double get_kmax( void ){
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return 1.e4;
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}
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};
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namespace{
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transfer_function_plugin_creator_concrete< transfer_eisenstein_plugin > creator("eisenstein");
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}
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