The incidence and evolution of Active Galactic Nuclei in 2865 COSMOS radio sources

• Applicant: Professor Dr. Ralf-Jürgen Dettmar, since 2/2017
• Subject Area: Astrophysics and Astronomy
• Term: from 2012 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 226167226

Observations using the Very Long Baseline Interferometry (VLBI) technique traditionally target carefully selected samples, to study particular aspects of their properties and surroundings. This situation is caused partly by the relative sparsity of sufficiently bright sources (or rather a lack of sensitivity), but mostly by the inherent technical difficulties of imaging multiple sources scattered across wide fields. Both aspects have undergone significant changes in the past few years, allowing observers to complement sensitive, wide-area radio observations with VLBI images. We have acquired 276h of observing time at the Very Long Baseline Array, to image all 2865 radio objects found in the COSMOS survey. The observations are going to use the new correlation and calibration techniques that we have developed with other workers in the field in previous wide-field VLBI observations. Since all known radio emitters in the COSMOS 2 sq-deg field are targeted, without other selection applied, the data will yield, for the first time, a sample of flux-limited, VLBI-detected objects in a large variety of galaxies. Furthermore, we have access to 200h of data from the VLBA to image all sources from the FIRST (Faint Images of the Radio Sky at Twenty Centimeters) survey in a 100 sq-deg region. Together these data sets will allow the investigation of VLBI radio sources from the Jy level to below 100 uJy. The main scientific goal of this project is to study the incidence and impact of radio-emitting AGN. We will (i) determine which objects host compact cores; (ii) determine how these objects affect the star formation in their host galaxies; and (iii) investigate the changes in accretion modes as a function of redshift. Furthermore, we anticipate significant input for additional, unexpected use cases of the survey data and input for follow-up observations. The COSMOS field has unrivalled optical, IR, X-ray, and spectroscopic coverage, and through a collaboration with members of the COSMOS project we have access to the data.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Dr. Enno Middelberg, until 1/2017