Author: Kayleigh Meneghini | Email: kayleighmeneghini@gmail.com
This package is available on PyPi.
For more details, please check this tutorial, using S-PLUS data.
# Installing
pip install galaxy-environment
# import
from galaxy_environment import environment
Any doubts about this package, please write to kayleighmeneghini@gmail.com
The environment has a decisive role in how galaxies evolve. We observed a strong correlation between galaxy properties such as color, morphology and their environment. However, the definition of environment makes this type of study non-trivial, after all, we can consider the local environment, as the association of a central galaxy and its satellites, or on larger scales, groups and clusters of galaxies.
There are two wide methods used to define the galactic environment, these are: Nearest Neighbors and Fixed Apertures.
In this package I have implemented the calculation of environmental estimators by these two methods, using the Python routines developed by Wright (2006) for calculating distances in cosmology.
The principle of Nearest Neighbors is that galaxies with closest neighbors are in denser environments and, therefore, have higher density fields. This method defines the galactic environment using a variable scale, depending on the number of neighbors of each galaxy. For each galaxy in the sample, values for k are chosen, this being the number of neighbors and calculate the distance to each of them around an interval of z.
This method, unlike the previous one, defines a scale for the environment around a fixed area or volume for each galaxy. So, the more galaxies within that area or volume, the denser the environment.
An alternative method proposed by Ivezic et. al (2005), considering distances to all K neighbors instead of only the distance to the K-th nearest neighbor