Search for molecular absorption in AGNs
PI: Dongjin Kim (DE)
CoIs:
Rainer Mauersberger (DE), Thomas Krichbaum (DE), Biagina Boccardi (DE), Michael Bremer (IRAMF), Christian Henkel (DE), Francoise Combes (FR)
Project ID: L19MC
Observing band: 3mm
Configuration: Any
Observing type: Detections
Abstract:
VLBI absorption lines studies allow to spatially locate and image the absorber in front of a bright and compact AGN-core, and by this test the Unified Scheme and hypothesis of a circum-nuclear torus. Here we focus on HCN and HCO+ as high density tracers for the matter which surrounds the VLBI-core and inner jet on sub-pc scales. As a preparatory study for more detailed follow-up VLBI imaging, we need to identify the most suitable targets. Thus we propose a spectral line survey to search for molecular absorption in a small but well-selected sample of galaxies, for which circum-nuclear absorption is expected. Using cross-matching of available source catalogues and selecting those source with high VLBI compactness, gas rich environment and favourable inclination, we have compiled a list of 22 sources for this pilot study. Here we aim to search for broad (100-1000 km/s) and red-shifted spectral line absorption features in the 3 mm band. Both, positive and negative detections we will allow tests of the receding torus model and will help to clarify the physical origin of the divide between FR 1 and FR 2 radio-galaxies.