Author: Jesse A. Rogerson, jesserogerson.com, rogerson@yorku.ca
The code implementation was written by the above, but with helpful (and crucial) contributions from: Catherine J. Grier, Patrick B. Hall, Daniel E. Vandenberk
This code calculates the 'BALnicity Index' of a quasar given some user-supplied spectrum.
In the literature, the definition of the BALnicity Index has gone through many iterations. Here we use BALnicity Index as a catch-all term for any measurement in the same spirit as the original BI (see below). This code is meant to be a one-stop-shop for all definitons. It allows the user to either:
a. choose from a set of predefined indexes
b. manually decide values of some or all of the parameters to define their own BALnicity Index
$> ./BALparams.py -h
This will output the various REQUIRED or 'positional arguments' as well as the various 'optional arguments.'
The only required inputs (or positional arguments) from the user are:
file: An ASCII spectrum of a quasar. It should be normalized to avoid bad pixels. It should be in the observed frame (it will be deredshifted in-program) The first three columns must be: #wavelength flux flux_err
zem: The Redshift of the quasar
With these, the user can execute:
$> ./BALparams.py file zem
Upon executing without any other parameters specified, BALparams.py will default to the original BI from Weymann et al. 1991, ApJ, 373, 23
There are a few pre-set BALnicity indexes that are available in this script: BI, BI_0, AI450, DI
If the user specifies one of these via the '-index' parameter on the commandline, it will automatically set the code to calculate that index.
$> ./BALparams.py file zem -index AI450
In the above example, all values of velocity ranges, minimum velocity, and more will be set to those used in the paper where AI450 was defined.
The user may choose to define any (or all) of the 'optional arguments' in the 'help' section. However, in order to make this work, the user MUST specify '-index man,' (see below)
e.g.,
$> ./BALparams.py file zem -index man -vlo 0 -vhi 35000
$> ./BALparams.py file zem -index man -vhi 35000 -zerr 0.056 -v 1000 -inc y
And any 'optional parameters' you do not set will remain the default BI values from Weymann et al. 1991
a. If you set '-index' to be one of the available pre-set indexes, it will override any additional optional parameters you set.
b. The code does not validate your optional parameters. So if you define a '-vlo' that is higher than the defined '-vhi,' the code will NOT yell at you.
c. The code will print out the configuration of the variables each time it runs, so you will know what you set.
Along with the script itself, an example output plot is provided named 'BALplot.eps' and included here. The plot was created using the following command:
$> BALparams.py spectrum.dat 2.5 -index man -vlo 0 -vhi 60000 -v 450 -inc y -out BALplot.png
 The shaded in blue regions are the portions of the spectrum that meet the BALnicity criteria as stipulated on the command line.
No Installation needed, just download and execute script.
see LICENSE.txt