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 0x7f42983632e0> |
+---------------+---------------------------------------------------------------+
| name          | 'parametric galaxy'                                           |
+---------------+---------------------------------------------------------------+
| sfzh (51, 13) | 0.00e+00 -> 5.84e+07 (Mean: 4.77e+05)                         |
+---------------+---------------------------------------------------------------+
+-----------------------------------------------------------------------------------------------+
|                                        LINECOLLECTION                                         |
+-------------------------+---------------------------------------------------------------------+
| Attribute               | Value                                                               |
+-------------------------+---------------------------------------------------------------------+
| nlines                  | 5                                                                   |
+-------------------------+---------------------------------------------------------------------+
| ndim                    | 1                                                                   |
+-------------------------+---------------------------------------------------------------------+
| nlam                    | 5                                                                   |
+-------------------------+---------------------------------------------------------------------+
| shape                   | (5,)                                                                |
+-------------------------+---------------------------------------------------------------------+
| available_ratios        | [R3, ]                                                              |
+-------------------------+---------------------------------------------------------------------+
| elements                | [H, O, O, O, O]                                                     |
+-------------------------+---------------------------------------------------------------------+
| line_ids (5,)           | [H 1 4861.32A, O 3 4958.91A, O 3 5006.84A, ...]                     |
+-------------------------+---------------------------------------------------------------------+
| lam (5,)                | 4.86e+03 Å -> 5.01e+03 Å (Mean: 4.96e+03 Å)                         |
+-------------------------+---------------------------------------------------------------------+
| luminosity (5,)         | 3.61e+41 erg/s -> 1.47e+42 erg/s (Mean: 8.58e+41 erg/s)             |
+-------------------------+---------------------------------------------------------------------+
| continuum (5,)          | 2.04e+27 erg/(Hz*s) -> 2.10e+27 erg/(Hz*s) (Mean: 2.09e+27 erg)     |
+-------------------------+---------------------------------------------------------------------+
| cont (5,)               | 2.04e+27 erg/(Hz*s) -> 2.10e+27 erg/(Hz*s) (Mean: 2.09e+27 erg)     |
+-------------------------+---------------------------------------------------------------------+
| continuum_llam (5,)     | 2.51e+38 erg/(s*Å) -> 2.59e+38 erg/(s*Å) (Mean: 2.54e+38 erg/(s*Å)) |
+-------------------------+---------------------------------------------------------------------+
| energy (5,)             | 2.48e+00 eV -> 2.55e+00 eV (Mean: 2.50e+00 eV)                      |
+-------------------------+---------------------------------------------------------------------+
| equivalent_width (5,)   | 1.39e+03 Å -> 5.86e+03 Å (Mean: 3.40e+03 Å)                         |
+-------------------------+---------------------------------------------------------------------+
| lum (5,)                | 3.61e+41 erg/s -> 1.47e+42 erg/s (Mean: 8.58e+41 erg/s)             |
+-------------------------+---------------------------------------------------------------------+
| nu (5,)                 | 5.99e+14 Hz -> 6.17e+14 Hz (Mean: 6.05e+14 Hz)                      |
+-------------------------+---------------------------------------------------------------------+
| vacuum_wavelengths (5,) | 4.86e+03 Å -> 5.01e+03 Å (Mean: 4.96e+03 Å)                         |
+-------------------------+---------------------------------------------------------------------+
+-------------------------------------------------------------------------------+
|                                    GALAXY                                     |
+---------------+---------------------------------------------------------------+
| Attribute     | Value                                                         |
+---------------+---------------------------------------------------------------+
| galaxy_type   | 'Parametric'                                                  |
+---------------+---------------------------------------------------------------+
| stars         | <synthesizer.parametric.stars.Stars object at 0x7f42983632e0> |
+---------------+---------------------------------------------------------------+
| name          | 'parametric galaxy'                                           |
+---------------+---------------------------------------------------------------+
| sfzh (51, 13) | 0.00e+00 -> 5.84e+07 (Mean: 4.77e+05)                         |
+---------------+---------------------------------------------------------------+
+-----------------------------------------------------------------------------------------------+
|                                        LINECOLLECTION                                         |
+-------------------------+---------------------------------------------------------------------+
| Attribute               | Value                                                               |
+-------------------------+---------------------------------------------------------------------+
| nlines                  | 5                                                                   |
+-------------------------+---------------------------------------------------------------------+
| ndim                    | 1                                                                   |
+-------------------------+---------------------------------------------------------------------+
| nlam                    | 5                                                                   |
+-------------------------+---------------------------------------------------------------------+
| shape                   | (5,)                                                                |
+-------------------------+---------------------------------------------------------------------+
| available_ratios        | [R3, ]                                                              |
+-------------------------+---------------------------------------------------------------------+
| elements                | [H, O, O, O, O]                                                     |
+-------------------------+---------------------------------------------------------------------+
| line_ids (5,)           | [H 1 4861.32A, O 3 4958.91A, O 3 5006.84A, ...]                     |
+-------------------------+---------------------------------------------------------------------+
| lam (5,)                | 4.86e+03 Å -> 5.01e+03 Å (Mean: 4.96e+03 Å)                         |
+-------------------------+---------------------------------------------------------------------+
| luminosity (5,)         | 1.17e+41 erg/s -> 4.91e+41 erg/s (Mean: 2.85e+41 erg/s)             |
+-------------------------+---------------------------------------------------------------------+
| continuum (5,)          | 6.59e+26 erg/(Hz*s) -> 7.00e+26 erg/(Hz*s) (Mean: 6.88e+26 erg)     |
+-------------------------+---------------------------------------------------------------------+
| cont (5,)               | 6.59e+26 erg/(Hz*s) -> 7.00e+26 erg/(Hz*s) (Mean: 6.88e+26 erg)     |
+-------------------------+---------------------------------------------------------------------+
| continuum_llam (5,)     | 8.37e+37 erg/(s*Å) -> 8.41e+37 erg/(s*Å) (Mean: 8.39e+37 erg/(s*Å)) |
+-------------------------+---------------------------------------------------------------------+
| energy (5,)             | 2.48e+00 eV -> 2.55e+00 eV (Mean: 2.50e+00 eV)                      |
+-------------------------+---------------------------------------------------------------------+
| equivalent_width (5,)   | 1.39e+03 Å -> 5.86e+03 Å (Mean: 3.40e+03 Å)                         |
+-------------------------+---------------------------------------------------------------------+
| lum (5,)                | 1.17e+41 erg/s -> 4.91e+41 erg/s (Mean: 2.85e+41 erg/s)             |
+-------------------------+---------------------------------------------------------------------+
| nu (5,)                 | 5.99e+14 Hz -> 6.17e+14 Hz (Mean: 6.05e+14 Hz)                      |
+-------------------------+---------------------------------------------------------------------+
| vacuum_wavelengths (5,) | 4.86e+03 Å -> 5.01e+03 Å (Mean: 4.96e+03 Å)                         |
+-------------------------+---------------------------------------------------------------------+

from unyt import Msun, Myr

from synthesizer.emission_models import AttenuatedEmission, NebularEmission
from synthesizer.emission_models.attenuation import PowerLaw
from synthesizer.emissions import O3, Hb, O3b, O3r
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
    nebular = NebularEmission(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. To do this we'll
    # first extract some line ratios from the `line_ratios` module, and then
    # Extract the individual lines from each ratio
    line_ids = [
        Hb,  # "H 1 4861.32A"
        O3b,  # "O 3 4958.91A"
        O3r,  # "O 3 5006.84A"
        O3,  # ["O 3 4958.91A", "O 3 5006.84A"]
    ]
    line_ids = [lid.strip() for lids in line_ids for lid in lids.split(",")]

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

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

    # 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_to=nebular,
    )

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