Oral Presentation

Chemical Model of the Circumnuclear Disk around an Active Galactic Nucleus

Nanase Harada (ASIAA), Todd Thompson (Ohio State), Eric Herbst (Univ. of Virginia)

We model the chemical composition in the circumnuclear disk (CND) around an active galactic nucleus (AGN) to explain the chemical features seen by observations. We consider an axisymmetric accretion disk models around an AGN a few 100s of parsecs using simple radial and vertical density and temperature distributions motivated by more detailed physical models. The effects of X-rays from the AGN, high gas temperature, and elevated dust temperatures are considered using both gas-phase and gas-grain chemical code. In X-ray dominated regions (XDRs) on the surface of the CND, radicals or ions such as CN or HCO+ become abundant, while relatively complex molecules such as HC3N can be abundant in dense regions shielded from X-rays, especially in high-temperature regions in the mid-plane. Higher dust temperature around an AGN prevents CH3OH to form in the vicinity of an AGN. Our results are also compared with recent results of ALMA observations of NGC 1068 of HCN, HCO+, HC3N, CH3OH, HNCO, CH3CN, CS, SO, and CN. Although further study is needed to fully understand the chemical features, it is likely that AGN chemistry is affected by high gas and dust temperature, and X-rays to create different observed distributions of different molecular species.