changing the emission line velocity width

Apologies if this information is in the documentation or in previously closed tickets, but I'd like to change (reduce) the velocity width of the emission lines without smoothing the stellar continuum. E.g., in the example below I would like to change the velocity width so the [OII] doublet is well-resolved.

According to the docs, smooth_velocity=True but smooth_lsf=False, by default, so there shouldn't be any supplemental smoothing. But clearly the lines are pretty broad (hard to tell, but I would guess >>100 km/s).

Any advice or guidance would be much-appreciated!

import fsps
import matplotlib.pyplot as plt

sp = fsps.StellarPopulation(compute_vega_mags=False, 
                            add_dust_emission=True,
                            add_neb_emission=True,
                            nebemlineinspec=True,
                            imf_type=1, # Chabrier
                            dust_type=0,
                            dust_index=-0.7,
                            sfh=0,
                            zcontinuous=1)
wave, flux = sp.get_spectrum(tage=1e-3, peraa=True)

I = (wave > 3697.) * (wave < 3757.)
fig, ax = plt.subplots()
ax.plot(wave[I], flux[I])
ax.set_xlabel('Wavelength (Angstrom)')
ax.set_ylabel('Flux')
fig.savefig('fsps-linewidth.png')

Lee primero la documentación de stellarpop_api y ejecuta el ejemplo de espectro incluido. Rastrea cómo smooth_velocity, smooth_lsf y nebemlineinspec afectan al continuo estelar y a las líneas de emisión; se considera completado identificar una forma compatible de estrechar el doblete de [OII] sin suavizar el continuo, o documentar que este comportamiento requiere un cambio independiente.