Basics
Overview
- Name:
Extragalactic Point Sources
- Author:
- Homepage:
- Paper:
Why do you need this code?
Use this code to generate the foregrounds due to extragalactic point radio sources.
A cosmological global 21-cm signal hides under foregrounds due to galactic and extragalactic emissions. These foregrounds can easily be 4 to 5 orders of magnitude higher than the signal of interest. For a reliable inference, it is important to accurately model these foregrounds. While we have a reasonable understanding of galactic emission (typically fit as a log-log polynomial), we do not understand the extragalactic contributions. This package models the foregrounds due to extragalactic point radio sources.
Read more about it in the paper Mittal et al (2024).
Installation and requirements
This package can be installed as
pip install epspy
We recommend working on a Python version > 3.8. Packages required are
Quick start
The code is run in two main steps:
Assign the point sources flux densities (at a chosen reference frequency) and spectral indices.
Then generate the sky maps at desired frequencies of observation.
The following code captures the main functionalities of this package.
from epspy import meps
#Step-1 initialise the object with default settings
obj = meps.eps()
#Step-2 generate the data at the reference frequency
obj.ref_freq()
#Step-3 generate the sky maps at multiple frequencies as well as their sky average
obj.gen_freq()
#Step-4 finally, generate a sky-averaged spectrum vs frequency figure
obj.visual()
Save the above code as (say) eg_script.py and run it as
python eg_script.py
Running the above will generate several files. The terminal messages will guide you to these output files. The most important of all files of your interest will be Tb_nu_map.npy. To visualise your outputs use the function visual(). See API Reference for the available features for visual(). To learn more about the output files and code working see Detailed explanation. To learn about the physics of this package see our paper.
In this package we have set the default values such that the users can run their scripts on a PC. Since modern PCs have at least 4 cores, for better performance, one could also run script eg_script.py parallelly as
mpirun -np 4 python eg_script.py
However, in general, and for more realistic flux density ranges and high-resolution maps, we recommend using the package on HPCs.
License and citation
The software is free to use on the MIT open-source license. If you use the software then please cite Mittal et al (2024).
If the code is used in a project where the author has provided significant scientific input, guidance on methodology, or assistance with interpretation of results, then co-authorship on resulting publications is expected, following standard academic practice.
Users are encouraged to contact the author when using the code for new scientific applications or major projects.
Acknowledgement
I thank Girish Kulkarni, Dominic Anstey, and Eloy de Lera Acedo for helpful comments and feedback during the development of this code.