Create sampled SED

this example generates a sample of star particles from a 2D SFZH. In this case it is generated from a parametric star formation history with constant star formation.

+-------------------------------------------------------------------------------------------------------+
|                                                 STARS                                                 |
+--------------------------+----------------------------------------------------------------------------+
| Attribute                | Value                                                                      |
+--------------------------+----------------------------------------------------------------------------+
| component_type           | 'Stars'                                                                    |
+--------------------------+----------------------------------------------------------------------------+
| sf_hist_func             | <synthesizer.parametric.sf_hist.Constant object at 0x7f500e15c850>         |
+--------------------------+----------------------------------------------------------------------------+
| metal_dist_func          | <synthesizer.parametric.metal_dist.DeltaConstant object at 0x7f500e15cf10> |
+--------------------------+----------------------------------------------------------------------------+
| metallicity_grid_type    | 'log10Z'                                                                   |
+--------------------------+----------------------------------------------------------------------------+
| log10ages_lims           | [6.0,  10.399999999999984, ]                                               |
+--------------------------+----------------------------------------------------------------------------+
| metallicities_lims       | [1e-05,  0.025118864315095104, ]                                           |
+--------------------------+----------------------------------------------------------------------------+
| log10metallicities_lims  | [-5.0,  -1.600000000000012, ]                                              |
+--------------------------+----------------------------------------------------------------------------+
| ages (45,)               | 1.00e+06 yr -> 2.51e+10 yr (Mean: 2.71e+09 yr)                             |
+--------------------------+----------------------------------------------------------------------------+
| metallicities (35,)      | 1.00e-05 -> 2.51e-02 (Mean: 3.49e-03)                                      |
+--------------------------+----------------------------------------------------------------------------+
| sf_hist (45,)            | 0.00e+00 -> 1.85e-01 (Mean: 2.22e-02)                                      |
+--------------------------+----------------------------------------------------------------------------+
| metal_dist (35,)         | 0.00e+00 -> 1.00e+00 (Mean: 2.86e-02)                                      |
+--------------------------+----------------------------------------------------------------------------+
| initial_mass             | 0.9999999999999999 Msun                                                    |
+--------------------------+----------------------------------------------------------------------------+
| sfzh (45, 35)            | 0.00e+00 -> 1.85e-01 (Mean: 6.35e-04)                                      |
+--------------------------+----------------------------------------------------------------------------+
| log10ages (45,)          | 6.00e+00 -> 1.04e+01 (Mean: 8.20e+00)                                      |
+--------------------------+----------------------------------------------------------------------------+
| log10metallicities (35,) | -5.00e+00 -> -1.60e+00 (Mean: -3.30e+00)                                   |
+--------------------------+----------------------------------------------------------------------------+

import matplotlib.pyplot as plt
import numpy as np
from unyt import Myr

from synthesizer.emission_models import IncidentEmission
from synthesizer.grid import Grid
from synthesizer.parametric import SFH, ZDist
from synthesizer.parametric import Stars as ParametricStars
from synthesizer.particle.galaxy import Galaxy
from synthesizer.particle.stars import sample_sfzh

# Define the grid
grid_name = "test_grid"
grid_dir = "../../tests/test_grid/"
grid = Grid(grid_name, grid_dir=grid_dir)

# Define the emission model
model = IncidentEmission(grid)

# define the grid (normally this would be defined by an SPS grid)
log10ages = np.arange(6.0, 10.5, 0.1)
metallicities = 10 ** np.arange(-5.0, -1.5, 0.1)

# define the parameters of the star formation and metal enrichment histories

Z_p = {"metallicity": 0.01}
metal_dist = ZDist.DeltaConstant(**Z_p)

sfh_p = {"duration": 100 * Myr}
sfh = SFH.Constant(**sfh_p)  # constant star formation
sfzh = ParametricStars(
    log10ages, metallicities, sf_hist=sfh, metal_dist=metal_dist
)
print(sfzh)
# sfzh.plot()


# --- create stars object

N = 100  # number of particles for sampling
stars = sample_sfzh(sfzh.sfzh, sfzh.log10ages, sfzh.log10metallicities, N)

# --- create galaxy object

galaxy = Galaxy(stars=stars)

""" this generates stellar and intrinsic spectra
galaxy.generate_intrinsic_spectra(grid, fesc=0.0)
calculate only integrated SEDs """
galaxy.stars.get_spectra(model)

# --- generate dust screen
# galaxy.get_screen(0.5) # tau_v

# --- generate CF00 variable dust screen
# galaxy.get_CF00(grid, 0.5, 0.5) # grid, tau_v_BC, tau_v_ISM

# --- generate for los model
# TODO: to be implemented
# tau_vs = np.ones(N) * 0.5
# galaxy.get_los(tau_vs)  # grid, tau_v_BC, tau_v_ISM

for sed_type, sed in galaxy.stars.spectra.items():
    plt.plot(np.log10(sed.lam), np.log10(sed.lnu), label=sed_type)

plt.legend()
plt.xlim([2, 5])
plt.ylim([10, 24])
plt.show()