English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We have combined Hubble Space Telescope/Faint Object Spectrograph,ground-based, and Infrared Space Observatory spectra of the nucleus of NGC4395, the least luminous and nearest known type 1 Seyfert galaxy. The spectrashow emission lines from a wide range of ionization states and criticaldensities. We have generated multicomponent photoionization models of both thebroad and narrow emission-line regions (BLR and NLR) to investigate thephysical conditions in the emission-line gas and test the proposition that thesource of ionization is the non-thermal continuum radiation emitted by thecentral source. We show that, with a minimum of free parameters, the modelpredictions match the observed emission-line ratios quite well. The elementalabundances appear to be subsolar, with even greater underabundance ofnitrogen.From the size of the BLR predicted by the models, we estimate acentral mass of a few x 10^5 solar masses, in reasonable agreement withestimates from the stellar kinematics. Finally, our results suggest that thecovering factor of the emission-line gas is close to unity, and that theobserved UV to X-ray continuum is absorbed by intervening NLR gas. We arguethat high covering factor is responsible for the apparent flattening of theBaldwin relation in low luminosity AGN.Comment: 44 pages, Latex, includes 4 figures, Fig. 1 has 2 parts, all figures  are encapsulated postscript except Fig. 3, which is just postscript, to  appear in the Astrophysical Journa

Physical Conditions in the Emission‐Line Gas in the Extremely Low Luminosity Seyfert Nucleus of NGC 4395