Generating Lines from a Parametric Galaxy

In this example we’re going to generate emission line predictions for a parametric galaxy.

+-------------------------------------------------------------------------------+
|                                    GALAXY                                     |
+---------------+---------------------------------------------------------------+
| Attribute     | Value                                                         |
+---------------+---------------------------------------------------------------+
| galaxy_type   | 'Parametric'                                                  |
+---------------+---------------------------------------------------------------+
| stars         | <synthesizer.parametric.stars.Stars object at 0x7fe804386110> |
+---------------+---------------------------------------------------------------+
| name          | 'parametric galaxy'                                           |
+---------------+---------------------------------------------------------------+
| sfzh (51, 13) | 0.00e+00 -> 5.84e+07 (Mean: 4.77e+05)                         |
+---------------+---------------------------------------------------------------+
----------
LINE COLLECTION
number of lines: 5
lines: ['H 1 4861.32A' 'O 3 4958.91A,O 3 5006.84A,H 1 4861.32A' 'O 3 4958.91A'
 'O 3 4958.91A,O 3 5006.84A' 'O 3 5006.84A']
available ratios: ['R3']
available diagrams: []
----------
----------
SUMMARY OF H 1 4861.32A
wavelength: 4861.3 Å
Npart: 1
<log10(luminosity/erg/s)>: -inf
<equivalent width>: 0 Å
----------
----------
SUMMARY OF O 3 4958.91A, O 3 5006.84A, H 1 4861.32A
wavelength: 4942.4 Å
Npart: 1
<log10(luminosity/erg/s)>: -inf
<equivalent width>: 0 Å
----------
----------
SUMMARY OF O 3 4958.91A
wavelength: 4958.9 Å
Npart: 1
<log10(luminosity/erg/s)>: -inf
<equivalent width>: 0 Å
----------
----------
SUMMARY OF O 3 4958.91A, O 3 5006.84A
wavelength: 4982.9 Å
Npart: 1
<log10(luminosity/erg/s)>: -inf
<equivalent width>: 0 Å
----------
----------
SUMMARY OF O 3 5006.84A
wavelength: 5006.8 Å
Npart: 1
<log10(luminosity/erg/s)>: -inf
<equivalent width>: 0 Å
----------
+-------------------------------------------------------------------------------+
|                                    GALAXY                                     |
+---------------+---------------------------------------------------------------+
| Attribute     | Value                                                         |
+---------------+---------------------------------------------------------------+
| galaxy_type   | 'Parametric'                                                  |
+---------------+---------------------------------------------------------------+
| stars         | <synthesizer.parametric.stars.Stars object at 0x7fe804386110> |
+---------------+---------------------------------------------------------------+
| name          | 'parametric galaxy'                                           |
+---------------+---------------------------------------------------------------+
| sfzh (51, 13) | 0.00e+00 -> 5.84e+07 (Mean: 4.77e+05)                         |
+---------------+---------------------------------------------------------------+
----------
LINE COLLECTION
number of lines: 5
lines: ['H 1 4861.32A' 'O 3 4958.91A,O 3 5006.84A,H 1 4861.32A' 'O 3 4958.91A'
 'O 3 4958.91A,O 3 5006.84A' 'O 3 5006.84A']
available ratios: ['R3']
available diagrams: []
----------

from unyt import Msun, Myr

import synthesizer.line_ratios as line_ratios
from synthesizer.emission_models import AttenuatedEmission, IncidentEmission
from synthesizer.emission_models.attenuation import PowerLaw
from synthesizer.grid import Grid
from synthesizer.parametric import SFH, Stars, ZDist
from synthesizer.parametric.galaxy import Galaxy

if __name__ == "__main__":
    # Begin by defining and initialising the grid.
    grid_name = "test_grid"
    grid_dir = "../../tests/test_grid/"
    grid = Grid(grid_name, grid_dir=grid_dir)

    # Define the emission model
    incident = IncidentEmission(grid)

    # Let's now build a galaxy following the other tutorials:
    # Define the functional form of the star formation and metal
    # enrichment histories

    # Constant star formation
    sfh = SFH.Constant(max_age=100 * Myr)

    # Constant metallicity
    metal_dist = ZDist.DeltaConstant(log10metallicity=-2.0)

    # Get the 2D star formation and metal enrichment history
    # for the given SPS grid. This is (age, Z).
    stars = Stars(
        grid.log10age,
        grid.metallicity,
        sf_hist=sfh,
        metal_dist=metal_dist,
        initial_mass=10**8.5 * Msun,
    )

    # Create the Galaxy object
    galaxy = Galaxy(stars)

    # Print a summary of the Galaxy object
    print(galaxy)

    # Let's define a list of lines that we're interested in. Note that we can
    # provide multiples which are automatically summed as if they were blended.
    line_ids = [
        line_ratios.Hb,  # "H 1 4861.32A"
        line_ratios.O3b,  # "O 3 4958.91A"
        line_ratios.O3r,  # "O 3 5006.84A"
        line_ratios.O3,  # ["O 3 4958.91A", "O 3 5006.84A"]
        line_ratios.O3
        + ","
        + line_ratios.Hb,  # ["O 3 4958.91A", "O 3 5006.84A", "H 1 4861.32A"]
    ]

    # Next, let's get the intrinsic line properties:
    lines = galaxy.stars.get_lines(line_ids, incident)

    # This produces a LineCollection object which has some useful methods and
    # information.
    print(lines)

    # Let's now examine individual lines (or doublets):
    for line in lines:
        print(line)

    # Those lines are now associated with the `Galaxy` object, revealed by
    # using the print function:
    print(galaxy)

    # Next, lets get the attenuated line properties:
    model = AttenuatedEmission(
        emitter="stellar",
        tau_v=1.0,
        dust_curve=PowerLaw(slope=-1),
        apply_dust_to=incident,
    )

    lines_att = galaxy.stars.get_lines(
        line_ids,
        model,
    )
    print(lines_att)