Optimized Spectral Energy Distribution for Seyfert Galaxies

Abstract

The temperature predicted by photoionization models for the narrow line region of Seyfert 2 galaxies is lower than the value inferred from the observed [OIII] λ4363Å/λ5007Å line ratio. We explore the possibility of considering a harder ionizing continuum than typically assumed. The spectral ionizing energy distribution, which can generate the observed λ4363Å/λ5007Å ratio, is characterized by a secondary continuum peak at 200 eV.

Spatially Resolved Temperature and Density Structures of Nearby H ii Regions

“…The measurement of electron densities across the θ 1 Ori C area shows that the density variation is not a monotonic function of distance to the ionizing star (Rubin et al 2011). In large nearby H II regions, the density gradients are observed to be flat (García-Benito et al 2010;Ramos-Larios et al 2010), while the density gradients appear to be negative in compact H II regions (Binette et al 2002;McLeod et al 2016).…”

“…The density distributions in most H II regions show filamentary or shell-like structures (Kennicutt 1984). The density measurements within these structures have diverse radial gradients (Binette et al 2002;Herrera-Camus et al 2016;Rubin et al 2016), although relatively uniform density distributions are seen in some cases (Garnett & Dinerstein 2001;Krabbe & Copetti 2002;García-Benito et al 2010). Surveys of both galactic and extragalactic H II regions indicate that approximately half the H II regions have internal variations in electron density (Copetti et al 2000;Malmann et al 2002).…”