The Covering Factor of Warm Dust in Quasars: View from WISE All-Sky Data Release

• Published in: arXiv.org
• Main Authors: Ma, Xiang-Cheng, Wang, Ting-Gui
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 16.01.2013
• Subjects: Active galactic nuclei; Anisotropy; Bolometers; Computer simulation; Correlation; Deposition; Dust; Extinction; Infrared photometry; Luminosity; Photometry; Physical properties; Physics - Cosmology and Nongalactic Astrophysics; Quasars; Sky surveys (astronomy); Ultraviolet spectra; Wide-field Infrared Survey Explorer
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1212.4245

By combining the newly infrared photometric data from the All-Sky Data Release of the Wide-field Infrared Survey Explorer with the spectroscopic data from the Seventh Data Release of the Sloan Digital Sky Survey, we study the covering factor of warm dust (\(\CF\)) for a large quasar sample, as well as the relations between \(\CF\) and other physical parameters of quasars. We find a strong correlation between the flux ratio of mid-infrared to near-ultraviolet and the slope of near-ultraviolet spectra, which is interpreted as the dust extinction effect. After correcting for the dust extinction utilizing the above correlation, we examine the relations between \(\CF\) and AGN properties: bolometric luminosity (\(\Lbol\)), black hole mass (\(\MBH\)) and Eddington ratio (\(L/L_{\rm Edd}\)). We confirm the anti-correlation between \(\CF\) and \(\Lbol\). Further we find that \(\CF\) is anti-correlated with \(\MBH\), but is independent of \(L/L_{\rm Edd}\). Radio-loud quasars are found to follow the same correlations as for radio-quiet quasars. Monte Carlo simulations show that the anisotropy of UV-optical continuum of the accretion disc can significantly affect, but is less likely to dominate the \(\CF\)--\(\Lbol\) correlation.