GalSpec package

This package is intended to quickly and easily generate a galaxy spectrum with a blackbody continuum emission and emission lines. The lines in this package are:

• CO lines
• SIII
• SiII
• OIII, OI
• NIII, NII
• CII, CI

Code by Tom Bakx, packaging and addition of molecular lines and rescaling by Stefanie Brackenhoff

Functionalities & Usage

• A spectrum can be generated using the spectrum() function.

It takes the following inputs:

• luminosity in units of log(L_fir [L_sol])
• redshift z
• fLow, fHigh minimum and maximum frequency that will be in the spectrum in units of GHz
• numFreqBins amount of linearly spaced frequency bins at which the spectrum should be evaluated
• linewidth width of spectral lines in units of km/s
• COlines 'Kamenetzky' 1 or 'Rosenberg' 2 determines the amplitude of the CO lines, default is Kamenetzky.
• lines 'Bonato' 3 or 'Spinoglio' 4 determines the amplitude of the remaining spectral lines, default is Bonato
• mollines 'True' or 'False'. Toggles whether molecularlines are shown. Values estimated using 5. Defaults as 'True'
• variance adds uncertainty to the amplitude of the atomic lines. Defaults to 0. Variation in molecular lines not implemented in the current version.
• manualrescale sets whether the lines should be default ratios by Kamenetzky/Rosenberg and Bonato/Spinoglio, or set by user. Options:
  • 'False' default line amplitudes used
  • 'Absolute' numpy array of 37 line amplitudes in Jy additive to blackbody emission can be set in rescaleArray. Additional entries ignored if mollines is set to 'False'.
  • 'Relative' numpy array of 37 scalars can be set in rescaleArray. The default ratios from Kamenetzky/Rosenberg are multiplied by these scalars prior to addition to the blackbody spectrum. Additional entries ignored if mollines is set to 'False'.
• rescaleArray rescales the emission lines according to setting in 'manualrescale'. Order of the lines can be found using linenames()

And creates as output:

• freqArray array frequencies in units of GHz
• spectrum array of the flux densities in the spectrum in units of Jy

• The spectrum can quickly be plotted using the plotspectrum() function

This function takes the outputs of spectrum() as an input and creates a plot with axis labels

• The names of the spectral lines and their order for the rescaleArray in spectrum() are outputted in a numpy array. Whether the names of molecular lines are shown can be toggled by setting the keyword mollines to 'False'.

Examples

• Simple example

import galspec

luminosity = 13.7
z = 4.43
fLow = 90 #GHz
fHigh = 910 #GHz
numFreqBins = 1500
linewidth = 600
gal_freq, gal_flux = galspec.spectrum(luminosity, z, fLow, fHigh, numFreqBins, linewidth, mollines = 'False')

galspec.plotspectrum(gal_freq, gal_flux)

• Using the ratios by Rosenberg and Spinoglio

import galspec

luminosity = 13.7
z = 4.43
fLow = 90 #GHz
fHigh = 910 #GHz
numFreqBins = 1500
linewidth = 600
gal_freq, gal_flux = galspec.spectrum(luminosity, z, fLow, fHigh, numFreqBins, linewidth, 'Rosenberg', 'Spinoglio', mollines = 'False')

galspec.plotspectrum(gal_freq, gal_flux)

• Using manual ratios to only show CO lines

import galspec
import numpy as np

luminosity = 13.7
z = 4.43
fLow = 90 #GHz
fHigh = 910 #GHz
numFreqBins = 1500
linewidth = 600

names = galspec.linenames()
lines = np.zeros(len(names))
for i in range(len(names)):
    if names[i].startswith('CO'): lines[i]=1

gal_freq, gal_flux = galspec.spectrum(luminosity, z, fLow, fHigh, numFreqBins, linewidth, manualrescale = 'Relative', rescaleArray = lines, mollines = 'False')

galspec.plotspectrum(gal_freq, gal_flux)

• Including molecular lines

import galspec
import numpy as np

luminosity = 13.7
z = 4.43
fLow = 90 #GHz
fHigh = 910 #GHz
numFreqBins = 1500
linewidth = 600


gal_freq, gal_flux = galspec.spectrum(luminosity, z, fLow, fHigh, numFreqBins, linewidth)

galspec.plotspectrum(gal_freq, gal_flux)

Installation

pip install galspec

Required packages

• Numpy
• astropy
• matplotlib
• scipy