Emission lines from post-AGB UV radiation

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
python
Domain
data

Research direction

Start by running the supplied Python script and inspect the get_spectrum call together with the pAGB, nebemlineinspec, and add_neb_emission parameters. Compare the resulting spectra for the three pAGB values; the issue is complete when the cause of the zero emission-line fluxes is identified and the expected behavior or required configuration is documented.

Written by the indexing model from the issue text.

Description

Hi,

I am running some models to test the UV contribution from the post-AGB stars to the emission lines of a galaxy. To test this, I use SSPs at the age of 3Gyrs (also tried for 0.1Gyrs and 5Gyrs). Models have no attenuation. The SSPs have solar metallicity. I test 3 separate instances which all have the same parameter values, except that each time I change the pAGB fraction to be 0, 0.5 and 1. I can see that I get ionizing radiation by turning on post-AGB stars.

The problem is that I get emission line fluxes that are all 0. Shouldn't this UV give emission lines for pAGB = 0.5 and pAGB = 1 ? Am I missing something obvious here?

From this tests I get the following plot:
3Gyr_SSP_no_att_add_neb_pAGB
0p1Gyr_SSP_no_att_add_neb_pAGB

The srcipt I run is the following:

import fsps
import matplotlib.pyplot as plt
import numpy as np

sp = fsps.StellarPopulation(zcontinuous=1)

sp.params['sfh'] = 0
sp.params['dust1'] = 0.0
sp.params['dust2'] = 0.0
sp.params['add_neb_emission'] = True
sp.params['add_dust_emission'] = True
sp.params['nebemlineinspec'] = True
sp.params['logzsol'] = 0.0
sp.params['gas_logz'] = sp.params['logzsol']

t = 3.0
for p in [0.0,0.5,1.0]:
	sp.params['pagb'] = p
	wave, flux = sp.get_spectrum(tage=t,peraa = True)
	plt.loglog(wave, flux,label='pAGB = ' + str(p))
	plt.xlabel('Wavelength (Angstroms)')
	plt.ylim([1e-7, 1e-2])
	plt.xlim([1e2, 1e5])
	plt.ylabel('Flux')
	plt.title('tage = ' + str(t)+'Gyr')
	plt.legend(fontsize=14)
plt.show()

Best,
Babis

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