NEW CONSTRAINTS ON THE QUASAR BROAD EMISSION LINE REGION
| Autor: | Andrea J. Ruff, Rachel L. Webster, David J. E. Floyd, Kirk T. Korista, Hermine Landt |
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| Rok vydání: | 2012 |
| Předmět: |
Physics
Luminous infrared galaxy Cosmology and Nongalactic Astrophysics (astro-ph.CO) Active galactic nucleus Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences Astronomy and Astrophysics Quasar Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Photoionization Astrophysics - Astrophysics of Galaxies Galaxy Spectral line Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Ionization Emission spectrum Astrophysics::Galaxy Astrophysics Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | The Astrophysical Journal. 754:18 |
| ISSN: | 1538-4357 0004-637X |
| DOI: | 10.1088/0004-637x/754/1/18 |
| Popis: | We demonstrate a new technique for determining the physical conditions of the broad line emitting gas in quasars, using near-infrared hydrogen emission lines. Unlike higher ionisation species, hydrogen is an efficient line emitter for a very wide range of photoionisation conditions, and the observed line ratios depend strongly on the density and photoionisation state of the gas present. A locally optimally emitting cloud model of the broad emission line region was compared to measured emission lines of four nearby ($z\approx0.2$) quasars that have optical and NIR spectra of sufficient signal-to-noise to measure their Paschen lines. The model provides a good fit to three of the objects, and a fair fit to the fourth object, a ULIRG. We find that low incident ionising fluxes ($\phih10^{12}$\cmcu) are required to reproduce the observed hydrogen emission line ratios. This analysis demonstrates that the use of composite spectra in photoionisation modelling is inappropriate; models must be fitted to the individual spectra of quasars. 12 pages, accepted for publication by ApJ |
| Databáze: | OpenAIRE |
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