The near-infrared host galaxy properties of radio-quiet "red AGN"

• Applicant: Dr. Knud Jahnke
• Subject Area: Astrophysics and Astronomy
• Term: from 2003 to 2004
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5412658

We want to study the nature of radio-quiet "red Active Galactic Nuclei" (AGN), i.e. quasars exibiting particularly red optical to near-infrared colours B-K bigger larger then 4. Two explanations have been put forward to explain these: extinction of the blue part of the spectrum due to dust in the host galaxy of the quasar, and second, a strong stellar near-infrared contribution of the host galaxy itself. In the context of "hidden quasars", a large fraction of AGN burried inside dust-enshrouded galaxies could be missed by traditional optical surveys. To tackle the question of the properties and light contribution of the host galaxies we successfully proposed to observe a sample of radio-quiet quasars with B-K larger than 4 at the Nordic Optical Telescope (NOT). In collaboration with swedish and british collaborators we were awarded time at the NOT to observe a unique data set of nine such objects, in the nearinfrared. A detailed morphological analysis will enable us to quantify the contribution of the host galaxy emission in this wavelength band and the object's possible morphological differences to "normal", blue quasars.

• DFG Programme: Research Grants