Merge pull request #195 from lincc-frameworks/jax_salt2_fixes

Fix the units for the JAX SALT2 model

src/tdastro/sources/salt2_jax.py

@@ -1,6 +1,9 @@
 from pathlib import Path
 
+from astropy import units as u
+
 from tdastro.astro_utils.salt2_color_law import SALT2ColorLaw
+from tdastro.astro_utils.unit_utils import flam_to_fnu
 from tdastro.sources.physical_model import PhysicalModel
 from tdastro.utils.bicubic_interp import BicubicInterpolator
 
@@ -58,6 +61,9 @@ class SALT2JaxModel(PhysicalModel):
         Any additional keyword arguments.
     """
 
+    # A class variable for the units so we are not computing them each time.
+    _FLAM_UNIT = u.erg / u.second / u.cm**2 / u.AA
+
     def __init__(
         self,
         x0=None,
@@ -101,6 +107,7 @@ def compute_flux(self, phase, wavelengths, graph_state, **kwargs):
             A length N array of wavelengths (in angstroms).
         graph_state : `GraphState`
             An object mapping graph parameters to their values.
+
         **kwargs : `dict`, optional
            Any additional keyword arguments.
 
@@ -118,4 +125,13 @@ def compute_flux(self, phase, wavelengths, graph_state, **kwargs):
             * (m0_vals + params["x1"] * m1_vals)
             * 10.0 ** (-0.4 * self._colorlaw.apply(wavelengths) * params["c"])
         )
+
+        # Convert to the correct units.
+        flux_density = flam_to_fnu(
+            flux_density,
+            wavelengths,
+            wave_unit=u.AA,
+            flam_unit=self._FLAM_UNIT,
+            fnu_unit=u.nJy,
+        )
         return flux_density

tests/tdastro/sources/test_salt2.py

@@ -2,33 +2,7 @@
 import pytest
 from sncosmo.models import SALT2Source
 from tdastro.sources.salt2_jax import SALT2JaxModel
-
-
-def test_salt2_model(test_data_dir):
-    """Test loading a SALT2 object from a file and querying it."""
-    dir_name = test_data_dir / "truncated-salt2-h17"
-    model = SALT2JaxModel(x0=0.5, x1=0.2, c=1.0, model_dir=dir_name)
-
-    assert model._colorlaw is not None
-    assert model._m0_model is not None
-    assert model._m1_model is not None
-
-    # Test compared to values computed via sncosmo's implementation that
-    # fall within the range of the truncated grid. We multiple by 1e12
-    # for comparison precision purposes.
-    times = np.array([1.0, 2.1, 3.9, 4.0])
-    waves = np.array([4000.0, 4102.0, 4200.0])
-    expected_times_1e12 = np.array(
-        [
-            [0.12842110, 0.17791164, 0.17462753],
-            [0.12287933, 0.17060205, 0.17152248],
-            [0.11121435, 0.15392100, 0.16234423],
-            [0.11051545, 0.15288580, 0.16170497],
-        ]
-    )
-
-    flux = model.evaluate(times, waves)
-    assert np.allclose(flux * 1e12, expected_times_1e12)
+from tdastro.sources.sncomso_models import SncosmoWrapperModel
 
 
 def test_salt2_model_parity(test_data_dir):
@@ -37,18 +11,22 @@ def test_salt2_model_parity(test_data_dir):
     """
     dir_name = test_data_dir / "truncated-salt2-h17"
     td_model = SALT2JaxModel(x0=0.4, x1=0.3, c=1.1, model_dir=dir_name)
-    sn_model = SALT2Source(modeldir=dir_name)
-    sn_model.set(x0=0.4, x1=0.3, c=1.1)
+
+    # We need to overwrite the source parameter to correspond to
+    # the truncated directory data.
+    sn_model = SncosmoWrapperModel("SALT2", x0=0.4, x1=0.3, c=1.1)
+    sn_model.source = SALT2Source(modeldir=dir_name)
 
     # Test compared to values computed via sncosmo's implementation that
     # fall within the range of the truncated grid. We multiple by 1e12
     # for comparison precision purposes.
     times = np.arange(-1.0, 15.0, 0.01)
     waves = np.arange(3800.0, 4200.0, 0.5)
 
+    # Allow TDAstro to return both sets of results in f_nu.
     flux_td = td_model.evaluate(times, waves)
-    flux_sn = sn_model._flux(times, waves)
-    assert np.allclose(flux_td * 1e12, flux_sn * 1e12)
+    flux_sn = sn_model.evaluate(times, waves)
+    assert np.allclose(flux_td, flux_sn)
 
 
 def test_salt2_no_model(test_data_dir):