This repository contains code to fit fast radio burst (FRB) or pulsar profiles to measure scattering and other parameters. The code is mainly developed for Python 3 from version 3.8 onwards.
The software is primarily developed and maintained by Fabian Jankowski. For more information feel free to contact me via: fabian.jankowski at cnrs-orleans.fr.
The corresponding paper (Jankowski et al. 2023, MNRAS) is available via this NASA ADS link.
If you make use of the software, please add a link to this repository and cite our corresponding paper. See above and the CITATION and CITATION.bib files.
The code is also listed in the Astrophysics Source Code Library (ASCL).
The easiest and recommended way to install the software is via the Python command pip directly from the scatfit GitHub software repository. For instance, to install the master branch of the code, use the following command:
pip install git+https://github.com/fjankowsk/scatfit.git@master
This will automatically install all dependencies. Depending on your Python installation, you might want to replace pip with pip3 in the above command.
Please verify that your installation works as expected by downloading a pre-generated SIGPROC filterbank file with synthetic data that comes bundled with the GitHub repository:
wget https://github.com/fjankowsk/scatfit/raw/master/extra/fake_burst_500_DM.fil
Then run the main analysis on the filterbank data file like this:
scatfit-fitfrb fake_burst_500_DM.fil 500.0 --fitscatindex --fscrunch 128 --norfi --fast
You should see several diagnostic windows open. The terminal output should show an updated DM close to 500 pc cm$^{-3}$, a scattering index near -4.0, and a scattering time at 1 GHz of about 20 ms.
To test the multi-component profile fitting mode, download the following SIGPROC filterbank file with a simulated 3-component profile:
wget https://github.com/fjankowsk/scatfit/raw/master/extra/fake_burst_10_DM_3-comp_coherent.fil
Then run the fitting on the filterbank like this:
scatfit-fitfrb fake_burst_10_DM_3-comp_coherent.fil 10.0 --norfi --fitrange -400 400 -z -100 200 --fscrunch 24 --center 0.0 --center 40.0 --center 70.0 --fitscatindex -o
The terminal output should show a DM close to 10 pc cm$^{-3}$, a scattering index near -0.25, and a scattering time at 1 GHz of around 1.5 ms. The component separations should be approximately 40 and 30 ms, respectively. The component sigmas should be close to 4, 4, and 6 ms.
Further documentation of the software is available on our dedicated Read the docs website.
$ scatfit-fitfrb -h
usage: scatfit-fitfrb [-h] [--center value] [--binburst bin] [--fast] [--fitrange start end] [--fscrunch factor]
[--tscrunch factor] [--norfi]
[--smodel {unscattered,scattered_isotropic_analytic,scattered_isotropic_convolving,scattered_isotropic_bandintegrated,scattered_isotropic_afb_instrumental,scattered_isotropic_dfb_instrumental}]
[--snr snr] [--compare] [--fitscatindex] [--showmodels] [--nodmsmearing] [-o] [--publish]
[-z start end]
filename dm
Fit a scattering model to FRB data.
positional arguments:
filename The name of the input filterbank file.
dm The dispersion measure of the FRB.
options:
-h, --help show this help message and exit
--center value The center of the model component. Use several times to define multiple model components. The
center values must be in increasing order. (default: [])
--binburst bin Specify the burst location bin manually. (default: None)
--fast Enable fast processing. This reduces the number of MCMC steps drastically. (default: False)
--fitrange start end Consider only this time range of data in the fit. Increase the region for wide or highly-
scattered bursts. Ensure that most of the scattering tail is included in the fit. (default:
[-150.0, 150.0])
--fscrunch factor Integrate this many frequency channels. (default: 256)
--tscrunch factor Integrate this many time samples. (default: 1)
--norfi Disable all internal RFI excision methods and use the input data as provided (aside from
scaling). This is useful for synthetic input data or if you have cleaned the data already using
external tools. (default: False)
--smodel {unscattered,scattered_isotropic_analytic,scattered_isotropic_convolving,scattered_isotropic_bandintegrated,scattered_isotropic_afb_instrumental,scattered_isotropic_dfb_instrumental}
Use the specified scattering model. (default: scattered_isotropic_analytic)
--snr snr Only consider sub-bands above this S/N threshold. (default: 10.0)
Additional analyses:
--compare Fit an unscattered Gaussian model for comparison. (default: False)
--fitscatindex Fit the scattering times and determine the scattering index. (default: False)
--showmodels Show comparison plot of implemented scattering models. (default: False)
Output formatting:
--nodmsmearing Do not show the DM smearing in the width scaling plot. This is useful for coherently dedispersed
data. (default: False)
-o, --output Output plots to file rather than to screen. (default: False)
--publish Output plots suitable for publication. (default: False)
-z, --zoom start end Zoom into this time region. (default: [-50.0, 50.0])$ scatfit-simpulse -h
usage: scatfit-simpulse [-h]
Simulate scattered pulses.
options:
-h, --help show this help message and exitSeveral profile scattering models, i.e. pulse broadening functions and instrumental contributions, are implemented and others can easily be added. The image below shows a selection of them.
The images below show some example output from the program obtained when fitting simulated filterbank data.
