Lyman-alpha radiation pressure: an analytical exploration

Mar 26, 2021
12 pages
Published in:
  • Mon.Not.Roy.Astron.Soc. 504 (2021) 1, 89-100
  • Published: May 3, 2021
e-Print:

Citations per year

202320242025041
Abstract: (Oxford University Press)
We study radiation pressure due to Ly α line photons, obtaining and exploring analytical expressions for the force-multiplier, M_F(N_H, Z) = F_α/(L_α/c), as a function of gas column density, N_H, and metallicity, Z, for both dust-free and dusty media, employing a WKB approach for the latter case. Solutions for frequency offset emission to emulate non-static media moving with a bulk velocity v have also been obtained. We find that, in static media, Ly α pressure dominates over both photoionization and dust-mediated UV radiation pressure in a very wide parameter range (16 < log N_H < 23; −4 < log [Z/Z_⊙] < 0). For example, it overwhelms the other two forces by |\lower.5ex\hbox{$\,\, \buildrel\gt \over \sim \,\,$}10| (300) times in standard (low-Z) star-forming clouds. Thus, in agreement with previous studies, we conclude that Ly α pressure plays a dominant role in the initial acceleration of the gas around luminous sources, and must be implemented in galaxy formation, evolution and outflow models and simulations.
  • radiative transfer
  • galaxies: high-redshift
  • dark ages, reionization, first stars