Near infrared hydrogen emission line ratios as diagnostics of the broad emission line region

Andrea J. Ruff, David J.E. Floyd, Kirk T. Korista, Rachel L. Webster, Ryan L. Porter, Gary J. Ferland

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations


Broad emission line flux ratios are a powerful diagnostic of the physical conditions of the broad-line region gas in Active Galactic Nuclei. With recent advances in infrared spectroscopy, previously unstudied emission lines provide a new means to investigate the physical nature of the BELR gas. The hydrogen emission lines are particularly sensitive to the upper limits of both the radius from the central ionising source and the number density of the gas. Using an existing subset of near-infrared quasar spectra from the Glikman et al. (2006) sample [1] together with Cloudy photoionization simulations, we confirm the Locally Optimally emitting Cloud (LOC) model's ability to reproduce observed emission line flux ratios. The model is then used to constrain physical conditions for individual sources. The photoionization models show that high number density, low incident flux gas is required to reproduce observed near-infrared hydrogen emission line ratios. We also find that comparison to individual sources, rather than composites, is vital.

Original languageEnglish
Article number012069
JournalJournal of Physics: Conference Series
StatePublished - 2012
EventAstronomy at High Angular Resolution 2011: The Central Kiloparsec in Galactic Nuclei, AHAR 2011 - Bad Honnef, Germany
Duration: Aug 29 2011Sep 2 2011

ASJC Scopus subject areas

  • General Physics and Astronomy


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