# models from Blondin et al. (2023), accepted for publication in A&A:
# "Nebular spectra from Type Ia supernova explosion models compared to
# JWST observations of SN 2021aefx" (arXiv:2306.07116)

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#		PLEASE REFERENCE BLONDIN ET AL. (2023)   	       #
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#	      IF YOU USE THESE RESULTS IN A PUBLICATION		       #
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# EXPLOSION MODELS
###################

The explosion models were obtained from the Heidelberg Supernova
Model Archive (HESMA; https://hesma.h-its.org), and correspond to
spherically-averaged versions of a 3D simulation. For the
ddt_2013_N100 model we also obtained non-spherically-averaged
radial profiles along the three orthogonal axes of the original 3D
Cartesian grid, in both positive ({x,y,z}pos) and negative
({x,y,z}neg) directions (Ivo Seitenzahl, priv. comm.)

Starting with the spherically-averaged density and abundance profiles
at t ~ 100 s post explosion available on HESMA, we generated initial
conditions at 270 d post explosion taking into account changes in
composition induced by the decay of radioactive isotopes (mainly 56Co
decay at this time) and the decrease in density due to homologous
expansion (density ~ 1/time^3). We applied a small radial mixing to
the HESMA inputs with a characteristic velocity width of ~300 or 400
km/s to smooth sharp variations in composition. The initial
temperature was set to 5000 K throughout the ejecta. These initial
conditions are reported in the files:

<model>_hydro_270d_initial.dat

We then solve the 1D non-LTE radiative transfer with CMFGEN assuming
steady state. Non-local energy deposition from radioactive decay (>
99.9% of which results from 56Co decay) was treated using a
Monte-Carlo approach for gamma-ray transport. Non-thermal processes
are accounted for through a solution of the Spencer-Fano equation. A
new temperature solution is produced by CMFGEN as part of the full
non-LTE solution. The converged model is given in the files: 

<model>_hydro_270d_converged.dat

NOTES:

- the initial conditions are at exactly 270.00 days post explosion,
  but the converged models are at 270.01 days post explosion (+0.01d
  later). This is a technicality to ensure CMFGEN takes into account
  radioactive decay energy deposition. Note also the reduced spatial
  grid in the converged model compared to the initial conditions,
  where high-velocity layers have been trimmed to improve convergence;

- the file formats are the same as those used for the supernova
  radiative-transfer code-comparison initiative (StaNdaRT) of the
  SNRadTrans collaboration (Blondin et al. 2022b, A&A 668, A163; see
  https://github.com/sn-rad-trans/data1/tree/master/input_models).


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# SYNTHETIC SPECTRA
####################

Synthetic nebular spectra correspond to 270 days post explosion (in
reality 270.01 days, see above). They were binned on on a 5-Angstrom
scale between 3500 and 280000 Angstroms (i.e., 0.35-28 microns) based
on the original observer-frame calculation.

Each spectrum follows the naming convention:

<model>_spec_3500_280000_bin5_270d.dat

The first column gives the (air) wavelength in Angstroms, the second
column gives the corresponding flux at 10 pc in erg/s/cm^2/A (such
that direct integration of the spectra using a given filter bandpass +
corresponding zero point will yield the absolute magnitude in that
filter), and the third column gives the continuum flux at 10 pc in
erg/s/cm^2/A .


For further information, please contact:

Stéphane Blondin (stephane.blondin@lam.fr)
