pith. sign in

Structure of Stationary Photodissociation Fronts

5 Pith papers cite this work. Polarity classification is still indexing.

5 Pith papers citing it
abstract

The structure of stationary photodissociation fronts is revisited. H_2 self- shielding is discussed, including the effects of line overlap. We find that line overlap is important for N(H_2) > 10^{20} cm^{-2}. We compute multiline UV pumping models, and compare these with simple analytic approximations for the effects of self-shielding. The overall fluorescent efficiency of the photodissociation front is obtained for different ratios of chi/n_H (where chi characterizes the intensity of the incident UV) and different dust extinction laws. The dust optical depth tau_{pdr} to the point where 50% of the H is molecular is found to be a simple function of a dimensionless quantity phi_0 depending on chi/n_H, the rate coefficient for H_2 formation on grains, and the UV dust opacity. The fluorescent efficiency of the PDR also depends primarily on phi_0 for chi<3000 and n_H<10^4 cm^{-3}; for stronger radiation fields and higher densities radiative and collisional depopulation of vibrationally-excited levels interferes with the radiative cascade. The emission spectrum from the PDR is essentially independent of the color temperature $T_{color}$ of the incident UV for T_{color}>10^4K, but shows some sensitivity to the v-J distribution of newly-formed H_2. The 1-0S(1)/2-1S(1) and 2-1S(1)/6-4Q(1) intensity ratios, the ortho/para ratio, and the rotational temperature in the $v$=1 and $v$=2 levels are computed as functions of the temperature and density, for different values of chi and n_H. We apply our models to the reflection nebula NGC 2023. We are best able to reproduce the observations with models having chi=5000, n_H=10^5 cm^{-3}.

citation-role summary

method 2

citation-polarity summary

years

2026 4 2025 1

verdicts

UNVERDICTED 5

roles

method 2

polarities

use method 2

clear filters

representative citing papers

21cmEMUv3: a hybrid diffusion-LSTM emulator of 21cmFAST summary observables

astro-ph.CO · 2026-05-29 · unverdicted · novelty 6.0

21cmEMUv3 emulates the cylindrical 21cm power spectrum via score-based diffusion and six other 21cmFAST observables via LSTM networks at sub-percent accuracy, then uses the emulator to infer a lower limit on soft-band X-ray luminosity from HERA data.

citing papers explorer

Showing 2 of 2 citing papers after filters.

  • 21cmEMUv3: a hybrid diffusion-LSTM emulator of 21cmFAST summary observables astro-ph.CO · 2026-05-29 · unverdicted · none · ref 9 · internal anchor

    21cmEMUv3 emulates the cylindrical 21cm power spectrum via score-based diffusion and six other 21cmFAST observables via LSTM networks at sub-percent accuracy, then uses the emulator to infer a lower limit on soft-band X-ray luminosity from HERA data.

  • Direct Collapse Black Hole Candidates from Decaying Dark Matter hep-ph · 2025-09-29 · unverdicted · none · ref 143 · internal anchor

    Axion dark matter decay injects 1-13.6 eV photons that suppress H2, enabling atomic cooling halos and direct collapse black hole seeds for axion masses 24.5-26.5 eV and couplings down to 4e-12/GeV.