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标题：A low-luminosity type-1 QSO sample - V. Overluminous host spheroids and their excitation mechanisms
其他标题：V. Overluminous host spheroids and their excitation mechanisms ⋆⋆⋆
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作者：Gerold Busch ; Gerold Busch ; Andreas Eckart 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2016
卷号：587
页码：1-18
DOI：10.1051/0004-6361/201526753
语种：English
出版社：EDP Sciences
摘要：We present near-infrared (NIR) H + K-band long-slit spectra of eleven galaxies that were obtained with SOFI at the NTT (ESO). The galaxies are chosen from the low-luminosity type-1 quasi-stellar object (LLQSO) sample, which comprises the 99 closest (z ≤ 0.06) QSOs from the Hamburg/ESO survey for bright UV-excess QSOs. These objects are ideal targets to study the gap between local Seyfert galaxies and high-redshift quasars because they show much stronger AGN activity than local objects, but are still close enough for a detailed structural analysis. We fit hydrogen recombination, molecular hydrogen, and [Fe ii] lines after carefully subtracting the continuum emission. From the broad Paα components, we estimated black hole masses and enlarged the sample of LLQSOs that deviate from the MBH − Lbulge relations of inactive galaxies from 12 to 16 objects. All objects show emission from hot dust (T ~ 1200 K) as well as stellar contribution. However, the respective fractions vary strongly among the objects. More than half of the objects show H2 emission lines, which indicate a large reservoir of molecular gas that is needed to feed the AGN and star formation. In the NIR diagnostic diagram all objects lie in the location of AGN-dominated objects. However, most of the objects show indications of star formation activity, suggesting that their offset location with respect to MBH–Lbulge relations of inactive galaxies may be a consequence of overluminous bulges.
关键词：galaxies: active;galaxies: starburst;galaxies: nuclei;galaxies: Seyfert;infrared: galaxies