A model for the scattered light contribution and polarization of the diffuse h alpha galactic background

May, 1999
9 pages
Published in:
  • Astrophys.J. 525 (1999) 799-807
e-Print:

Citations per year

1999200520112017202202468
Abstract: (arXiv)
We present Monte Carlo simulations of the Diffuse Hα\alpha Galactic Background. Our models comprise direct and multiply scattered Hα\alpha radiation from the kpc scaleheight Warm Ionized Medium and midplane H II regions. The scattering is off dust that is assumed to be well mixed with the gas, with an axisymmetric density distribution taken from the literature. The results of our simulations are all-sky Hα\alpha images that enable us to separate out the contributions of direct and scattered radiation. We also determine how far the model Hα\alpha photons have traveled, i.e., how far we see into the Galaxy at Hα\alpha. Our models reproduce the overall characteristics of the observed Hα\alpha background and predict the scattered Hα\alpha intensity at high latitudes is in the range 5% to 20% of the total intensity, in agreement with estimations based on [S II]/Hα\alpha and [O III]/Hα\alpha line ratio measurements. The polarization arising from dust scattering of Hα\alpha from midplane H II regions is predicted to be less than 1% at high latitude.