SALSA

SALSA (Synthetic Absorption Line Surveyor Application) is a Python tool that constructs synthetic absorber catalogs from hydrodynamic galaxy simulations. SALSA heavily utilizes yt to access simulation data and Trident to create light rays/sight lines and generate synthetic spectra.

Observational studies generate large absorber catalogs by studying the absorption line spectra of distant quasars, as their light passes through intervening galaxies. SALSA can generate similar catalogs from cosmological and galactic simulations, allowing research to study these simulations from an observers perspective. This can give new insights into the data as well as help facilitate comparisons and collaboration between simulations and observations.

SALSA allows us to dip into galactic simulations and start to chip away at the many unknowns of the universe

A JOSS paper was published for SALSA and we recommend reading it for an overview of the package and its possible uses. If you do use SALSA in a project we ask that you cite this paper.

For detailed information on how to install and run SALSA, Read the Docs here

Install

We recommending checking the documentation for advice on installing the core dependencies.

Once you have the trickier dependencies installed, you can use pip and run these commands to install the most stable version:

  $ pip install astro-salsa
  $ python
  >>> import salsa

If you want to install the latest development version, you can clone the repository and run these commands to install the additional dependencies necessary for testing and building the documentation:

  $ git clone https://github.com/biboyd/SALSA.git
  $ cd SALSA
  $ pip install -e .[dev]
  $ python
  >>> import salsa

Now you should be all set to code!

Installing dependencies

The requirements.txt file contains the minimum dependencies needed to run SALSA.

Note that you need gcc compiler installed (which it often already is on most machines). For a more detailed description see the installation guide which also includes tips if you want to install dependencies on your own.

To install the basic dependencies with pip, run

pip install -r requirements.txt

If you prefer to use conda, you cannot use the requirements.txt file directly as Trident is not available via conda. You'll also still need to install SALSA with pip as above. Make sure pip is installed in your conda environment!

Getting Started

For an annotated example go here. Or launch an interactive jupyter hosted on Binder here (note that the notebook may take some time to load as it generally has to build the repository).

If you want to explore on your own, the easiest way to get started is use salsa.generate_catalog(). This takes:

• The simulation dataset (either as a path or an object loaded by yt)
• Number of light rays/sightlines to make
• Directory to save those light rays
• A list of ions
• Some other optional parameters.
  This creates a number light rays and then extracts absorbers for each ion. An Astropy QTable is returned with information about all the absorbers which can then be further analyzed.

Building the Documentation

If you installed SALSA with pip install astro-salsa[dev] or pip install -e .[dev], you'll be able to build the documentation locally:

  $ cd docs
  $ make html  # or latexpdf if you prefer

This will create a docs/build/ folder that contains the documentation.

Contributing Guidelines

All contributions are welcome! This is an open-source project, built on many other open-source projects. Contributing can take many forms including: contributing code, testing and experimenting, or offering ideas for different features.

If you are interested in contributing you can contact us directly at kopenhaf@msu.edu or add an issue on this Github page.