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Nearby QSOs: A sample of low-luminosity type-1 QSOs

Active galactic nuclei (AGN) have been subject to lively discussions in extragalactic astrophysics for many years. A unified model has been established explaining the numerous appearances of AGN with varying orientation relative to the line of sight.

Other models deal with the evolution of AGN and the interaction between the active nucleus and the galaxy hosting it. These models take account of enhanced star formation during the evolutionary process and the demand of an abundant supply of material to fuel the AGN.

To gather further insights and to be able to test existing models of AGNs, the environment hosting the nucleus should be studied in more detail. Therefore it is necessary to separate the AGN and star-burst regions and determine the properties of the hosts stellar population and interstellar medium.
Quasi-stellar objects (QSOs) with their exceptionally optically bright nuclei form a very interesting subgroup among AGN, since they are the most active ones of their species. Though, because of the nuclei's dominating radiation outshining their surroundings, it is challenging to observe the galaxies that host QSOs.

Nevertheless, with sophisticated observation techniques, namely with the use of Interferometers such as ALMA or NOEMA in the mm-wavelength - or LBT and VLT in the NIR domain, high resolution imaging observations of the closest of these objects can be performed. In combination with additional multi-wavelength data, detailed studies of the properties of nearby QSO host galaxies are possible.

Conclusions from these nearby objects again allow a detailed interpretation of high-z QSO host data.

Near-Infrared H-band images of nine QSOs from the Hamburg/ESO survey, obtained with SOFI at the NTT (ESO). The croresponding Hamburg/ESO survey name of galaxies can be found in Busch et al. 2016. North is up, east is left.

Credit: aegroup, PH1