Techniques for profile binning and analysis of eigenvector composite spectra: Comparing Hβ and Mgiiλ2800 as virial estimators
We review the basic techniques for extracting information about quasar structure and kinematics from the broad emission lines in quasars. We consider which lines can most effectively serve as virial estimators of black hole mass. At low redshift the Balmer lines, particularly broad Hβ, are the lines...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2014 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/400794 |
| Acceso en línea: | http://hdl.handle.net/10261/400794 |
| Access Level: | acceso abierto |
| Palabra clave: | Line:formation Line: profile Quasars: emission lines Quasars: general |
| Sumario: | We review the basic techniques for extracting information about quasar structure and kinematics from the broad emission lines in quasars. We consider which lines can most effectively serve as virial estimators of black hole mass. At low redshift the Balmer lines, particularly broad Hβ, are the lines of choice. For redshifts greater than 0.7 - 0.8 one can follow Hβ into the IR windows or find an Hβ surrogate. We explain why UV CIVλ1549 is not a safe virial estimator and how MgIIλ2800 serves as the best virial surrogate for Hβ up to the highest redshift quasar known at z≈7. We show how spectral binning in a parameter space context (4DE1) makes possible a more effective comparison of Hβ and MgII. It also helps to derive more accurate mass estimates from appropriately binned spectra and, finally, to map the dispersion in MBH and Eddington ratio across the quasar population. FWHM MgII is about 20% smaller than FWHM Hβ in the majority of type 1 AGN requiring correction when comparing MBH estimates from these two lines. The 20% of sources showing narrowest FWHM Hβ (<4000 km s-1) and strongest FeII (RFe≳1.0) emission (we call them bin A3-4 sources) do not show this FWHM difference and a blueshift detected in MgII for these sources suggests that FWHM Hβ is the safer virial estimator for these extreme Eddington emitters. © 2013 COSPAR. Published by Elsevier Ltd |
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