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Analysing Spectrum

Every simulation run requires atomic data and a configuration file.

Atomic Data

We recommend using the kurucz_cd23_chianti_H_He.h5 dataset.

from tardis.io.atom_data import download_atom_data

# We download the atomic data needed to run the simulation
download_atom_data("kurucz_cd23_chianti_H_He")

Atomic Data kurucz_cd23_chianti_H_He already exists in /home/abhinav/Downloads/tardis-data/kurucz_cd23_chianti_H_He.h5. Will not download - override with force_download=True.

You can also obtain a copy of the atomic data from the tardis-regression-data repository.

Example Configuration File

The configuration file tardis_example.yml is used throughout this Quickstart.

!wget -q -nc https://raw.githubusercontent.com/tardis-sn/tardis/master/docs/tardis_example.yml

!cat tardis_example.yml

# Example YAML configuration for TARDIS
tardis_config_version: v1.0

supernova:
  luminosity_requested: 9.44 log_lsun
  time_explosion: 13 day

atom_data: kurucz_cd23_chianti_H_He.h5

model:
  structure:
    type: specific
    velocity:
      start: 1.1e4 km/s
      stop: 20000 km/s
      num: 20
    density:
      type: branch85_w7

  abundances:
    type: uniform
    O: 0.19
    Mg: 0.03
    Si: 0.52
    S: 0.19
    Ar: 0.04
    Ca: 0.03

plasma:
  disable_electron_scattering: no
  ionization: lte
  excitation: lte
  radiative_rates_type: dilute-blackbody
  line_interaction_type: macroatom

montecarlo:
  seed: 23111963
  no_of_packets: 4.0e+4
  iterations: 20
  nthreads: 1

  last_no_of_packets: 1.e+5
  no_of_virtual_packets: 10

  convergence_strategy:
    type: damped
    damping_constant: 1.0
    threshold: 0.05
    fraction: 0.8
    hold_iterations: 3
    t_inner:
      damping_constant: 0.5

spectrum:
  start: 500 angstrom
  stop: 20000 angstrom
  num: 10000

Running the Simulation

To run the simulation, import the run_tardis function and create the sim object.

Note:

Get more information about the progress bars, logging configuration, and convergence plots.

from tardis import run_tardis

sim = run_tardis(
    "tardis_example.yml",
    log_level="ERROR"
)

[py.warnings         ][WARNING]
        /home/abhinav/workspace/code/tardis-main/tardis-code/tardis/tardis/transport/montecarlo/montecarlo_main_loop.py:123: NumbaTypeSafetyWarning:

unsafe cast from uint64 to int64. Precision may be lost.

 (warnings.py:112)

HDF

TARDIS can save simulation data to HDF files for later analysis. The code below shows how to load a simulation from an HDF file. This is useful when you want to analyze simulation results without re-running the simulation.

# import astropy.units as u
# import pandas as pd

# hdf_fpath = "add_file_path_here"
# with pd.HDFStore(hdf_fpath, "r") as hdf:
#     sim = u.Quantity(hdf["/simulation"])

Calculate integrated spectrum

Note:

It takes about a minute to calculate. Please be patient while it runs.

spectrum_integrated = sim.spectrum_solver.spectrum_integrated

[py.warnings         ][WARNING]
        /home/abhinav/workspace/code/tardis-main/tardis-code/tardis/tardis/spectrum/formal_integral.py:398: UserWarning:

The number of interpolate_shells was not specified. The value was set to 80.

 (warnings.py:112)

Plotting the Spectrum

Now we will plot the spectrum using matplotlib and plotly. The plots show the luminosity density as a function of wavelength.

• Wavelength [:math:`AA`]: The x-axis represents the wavelength in Angstroms.

• Luminosity density [:math:`ergs^{-1}AA^{-1}`]: The y-axis represents the luminosity density in erg per second per Angstrom.

Matplotlib

We use Matplotlib to create a static plot of the formal integral spectrum that was calculated in the previous step.

import matplotlib.pyplot as plt

# Create a new figure with specified dimensions
plt.figure(figsize=(10, 6.5))

spectrum_integrated.plot(label="Formal integral")  # Plot spectrum from formal integral solution

# Set title, labels, and template
plt.xlim(500, 9000)
plt.title("TARDIS example model spectrum")
plt.xlabel(r"Wavelength [$\AA$]")
plt.ylabel(r"Luminosity density [$ergs^{-1}\AA^{-1}$]")
plt.legend()
plt.show()

Plotly

Here, we use Plotly to create an interactive plot of the virtual packet spectrum generated by the TARDIS simulation.

import plotly.graph_objects as go

# Create a new figure for plotting the spectrum
fig = go.Figure()

# Plot the wavelength spectrum
fig.add_trace(
    go.Scatter(
        x=sim.spectrum_solver.spectrum_virtual_packets.wavelength,
        y=sim.spectrum_solver.spectrum_virtual_packets.luminosity_density_lambda,
        mode="lines",
        name="Spectrum"
    )
)

# Set title, labels, and template
fig.update_layout(
    title="TARDIS example model spectrum",
    xaxis_title=r"Wavelength [$\overset{\circ}{A}$]",
    yaxis_title=r"Luminosity density [$ergs^{-1}\overset{\circ}{A^{-1}}$]", # Plotly doesnot support the Angstrom symbol so we are using a close approximation of it
    xaxis_range=[500, 9000],
    showlegend=True,
    template="plotly_white"
)

# Display the plot
fig.show()