TauREx-petitRADTRANS plugin

Current version: 0.3.0-alpha

TauREx-petitRADTRANS is a plugin that allows for the use of petitRADTRANS opacities and forward models in TauREx

Installing

Installing the plugin from PyPI requires only a single command:

pip install taurex_petitrad

You can also install from source by doing:

git clone https://github.com/ucl-exoplanets/taurex-petitrad
cd taurex-petitrad
pip install .

Using opacities

Once installed you have access to both petitRADTRANS line-by-line cross-sections and k-tables. You can either set the xsec_path or ktable_path to the input_data folder in petitRADTRANS:

[Global]
xsec_path = /path/to/petitRADTRANS/petitRADTRANS/input_data/
ktable_path = /path/to/petitRADTRANS/petitRADTRANS/input_data/

Or by setting petitrad_path to the root petitRADTRANS folder

[Global]
petitrad_path = /path/to/petitRADTRANS/petitRADTRANS/

You can include both if you desire, petitrad_path will be prioritized.

Using forward models

To use the forward models, the petitrad_path must be set to the root petitRADTRANS folder. TauREx 3 will automatically include the package into Python so there is no need to modify system paths.

Once done, you will have access to three new forward models:

Transmission

Transmission spectra can be accessed through the model_type keyword by setting it as either transmission-petitrad or transit-petitrad

[Model]
model_type = transmission-petitrad
continuum_opacities = H2-H2, H2-He
wlen_bords_micron = 0.3,15.0

The available arguments are:

Argument	Description	Type	Default	Required
rayleigh_species	Rayleigh species to include	list of molecules	None
continuum_species	CIA species	list of molecule pairs	None
wlen_bords_micron	Wavelength range in um	array	0.3, 15
Pcloud	Grey cloud deck pressure in Pa	float	None
gamma_scat	Powerlaw index	integer	None
kappa_zero	Powerlaw cloud opacity term in cm2/g	float	None
haze_factor	Rayleigh opacity scale term	float	None

For the more through explaination of cloud terms please refer to this documentation.

The available retrieval parameters are:

|Fitting Parameter| Description| Pcloud | Grey cloud deck pressure in Pa | gamma_scat | Powerlaw index | kappa_zero | Powerlaw cloud opacity term in cm2/g | haze_factor | Rayleigh opacity scale term |

Eclipse and Direct imaging

The eclipse spectra can be generated using the emission-petitrad or eclipse-petitrad keyword

[Model]
model_type = eclipse-petitrad
continuum_opacities = H2-H2, H2-He
wlen_bords_micron = 0.3,15.0

And direct imaging as through by directimage-petitrad or direct-petitrad:

[Model]
model_type = directimage-petitrad
continuum_opacities = H2-H2, H2-He
wlen_bords_micron = 0.3,15.0

Both have the same arguments available:

Argument	Description	Type	Default	Required
rayleigh_species	Rayleigh species to include	list of molecules	None
continuum_species	CIA species	list of molecule pairs	None
wlen_bords_micron	Wavelength range in um	array	0.3, 15

There are no extra retrieval parameters provided by these forward models

Limitations

Currently no condensate opacities are supported as the current release of TauREx does not have a comprehensive enough scattering framework to prevent incompatibility with other models. Future releases will allow for their inclusion.

The majority of TauREx and its plugins can be used with the petitRADTRANS models such as chemistries, temeperature profiles, samplers, non-uniform priors etc. The only exception are the contributions. This is because the integral is being performed by petitRADTRANS itself, therefore some plugins (such as TauREx-CUDA) cannot be used. Attempting to add any TauREx contribution object such as:

[Model]
model_type = transmission-petitrad
continuum_opacities = H2-H2, H2-He
wlen_bords_micron = 0.3,15.0
    [[Absorption]]

    [[HydrogenIon]]

    [[Rayleigh]]

Will result in the error:

ValueError: TauREx 3 contributions are not supported with the petitRADTRANS forward models