A low-luminosity type-1 QSO sample. V. Overluminous host spheroids and their excitation mechanisms
Abstract
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.
Based on observations with ESO-NTT, proposal No. 83.B-0739.Reduced spectra of the galaxies are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A138- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 2016
- DOI:
- 10.1051/0004-6361/201526753
- arXiv:
- arXiv:1511.00904
- Bibcode:
- 2016A&A...587A.138B
- Keywords:
-
- galaxies: active;
- galaxies: starburst;
- galaxies: nuclei;
- galaxies: Seyfert;
- infrared: galaxies;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 18 pages, 9 figures