The Irradiated ISM of Active Galaxies: HCN, HNC, HCO⁺

Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands

Abstract

The nuclei of active galaxies harbor massive young stars, an accreting central black hole, or both. Results are presented for molecular gas that is exposed to X-rays (1–100 keV, XDRs) and far-ultraviolet radiation (6–13.6 eV, PDRs). Particular attention is paid to species like HCN, HNC and HCO⁺. Line ratios of HCN/HCO⁺ and HNC/HCN discriminate between PDRs and XDRs.