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Outflow and Hot Dust Emission in High-redshift Quasars

【标题】Outflow and Hot Dust Emission in High-redshift Quasars

【Title】Outflow and Hot Dust Emission in High-redshift Quasars

【DOI】10.1088/2041-8205/776/1/L15

【作者】 Huiyuan Wang; Feijun Xing; Kai Zhang; Tinggui Wang; 周宏岩; 张少华

【Author】 Huiyuan Wang ; Feijun Xing ; Kai Zhang ; Tinggui Wang ; Zhou Hongyan ; Zhang Shaohua

【期刊】The Astrophysical Journal Letters

【Journal】The Astrophysical Journal Letters

【期刊年份】2013

【卷】776

【期】1

【关键词】 dust, extinction, galaxies: nuclei, infrared: galaxies, quasars: emission lines, quasars: general

【Keywords】 dust, extinction, galaxies: nuclei, infrared: galaxies, quasars: emission lines, quasars: general

【摘要】Correlations of hot dust emission with outflow properties are investigated, based on a large z ~ 2 non-broad absorption line quasar sample built from the Wide-field Infrared Survey and the Sloan Digital Sky Survey data releases. We use the near-infrared slope and the infrared to UV luminosity ratio to indicate the hot dust emission relative to the emission from the accretion disk. In our luminous quasars, these hot dust emission indicators are almost independent of the fundamental parameters, such as luminosity, Eddington ratio and black hole mass, but moderately dependent on the blueshift and asymmetry index (BAI) and FWHM of C IV lines. Interestingly, the latter two correlations dramatically strengthen with increasing Eddington ratio. We suggest that, in high Eddington ratio quasars, C IV regions are dominated by outflows so the BAI and FWHM (C IV) can reliably reflect the general properties and velocity of outflows, respectively. In low Eddington ratio quasars, on the other hand, C IV lines are primarily emitted by virialized gas so the BAI and FWHM (C IV) become less sensitive to outflows. Therefore, the correlations for the highest Eddington ratio quasars are more likely to represent the true dependence of hot dust emission on outflows and the correlations for the entire sample are significantly diluted by the low Eddington ratio quasars. Our results show that an outflow with a large BAI or velocity can double the hot dust emission on average. We suggest that outflows either contain hot dust in themselves or interact with the dusty interstellar medium or torus.

【Abstract】Correlations of hot dust emission with outflow properties are investigated, based on a large z ~ 2 non-broad absorption line quasar sample built from the Wide-field Infrared Survey and the Sloan Digital Sky Survey data releases. We use the near-infrared slope and the infrared to UV luminosity ratio to indicate the hot dust emission relative to the emission from the accretion disk. In our luminous quasars, these hot dust emission indicators are almost independent of the fundamental parameters, such as luminosity, Eddington ratio and black hole mass, but moderately dependent on the blueshift and asymmetry index (BAI) and FWHM of C IV lines. Interestingly, the latter two correlations dramatically strengthen with increasing Eddington ratio. We suggest that, in high Eddington ratio quasars, C IV regions are dominated by outflows so the BAI and FWHM (C IV) can reliably reflect the general properties and velocity of outflows, respectively. In low Eddington ratio quasars, on the other hand, C IV lines are primarily emitted by virialized gas so the BAI and FWHM (C IV) become less sensitive to outflows. Therefore, the correlations for the highest Eddington ratio quasars are more likely to represent the true dependence of hot dust emission on outflows and the correlations for the entire sample are significantly diluted by the low Eddington ratio quasars. Our results show that an outflow with a large BAI or velocity can double the hot dust emission on average. We suggest that outflows either contain hot dust in themselves or interact with the dusty interstellar medium or torus.

【基金/项目】 NSFC (11073017, 11033007) ; 973 program (2009CB824800)

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