Non-LTE Effects on the Strength of the Lyman Edge in Quasar Accretion Disks
Abstract
We have calculated UV/EUV (300 A <= λ <= 1500 A) continuous energy distributions of accretions disks in the centers of active galactic nuclei (AGNs) for disk luminosities in the range 0.1L_Edd <= L_acc_ < 1.0L_Edd_ and central masses ranging from 10^8^ M_sun_ to 10^9^ M_sun_. The vertical gas pressure structure of the disk and the disk height are obtained analytically; the temperature stratification and the resulting continuum radiation fields are calculated numerically. We have included non-LTE effects of both the ionization equilibrium and the level populations of hydrogen and helium. We show that these non-LTE effects reduce the strength of the Lyman edge when compared to the LTE case. In non-LTE we find that the edge can be weakly in emission or absorption for disks seen face-on, depending on the disk parameters.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1994
- DOI:
- 10.1086/187690
- Bibcode:
- 1994ApJ...437L..91S
- Keywords:
-
- Accretion Disks;
- Active Galactic Nuclei;
- Galactic Structure;
- Local Thermodynamic Equilibrium;
- Numerical Analysis;
- Quasars;
- Ultraviolet Astronomy;
- Abundance;
- Lyman Spectra;
- Radiative Transfer;
- Astrophysics;
- ACCRETION;
- ACCRETION DISKS;
- GALAXIES: ACTIVE;
- METHODS: NUMERICAL;
- RADIATIVE TRANSFER