Active galactic nuclei winds as the origin of the H2 emission excess in nearby galaxies

• Autor(a) principal: Riffel, Rogemar André
• Data de Publicação: 2020
• Outros Autores: Zakamska, Nadia L., Riffel, Rogério
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/206911
• topic: Galáxias ativas; Meio interestelar; Cinemática; Nucleo galatico; Galaxies: active; Galaxies: ISM; Galaxies: kinematics and dynamics; Galaxies: nuclei

In most galaxies, the fluxes of rotational H2 lines strongly correlate with star formation diagnostics [such as polycyclic aromatic hydrocarbons (PAHs)], suggesting that H2 emission from warm molecular gas is a minor by-product of star formation. We analyse the optical properties of a sample of 309 nearby galaxies derived from a parent sample of 2015 objects observed with the Spitzer Space Telescope. We find a correlation between the [O I]λ6300 emission-line flux and kinematics and the H2 S(3) 9.665 μm/PAH 11.3 μm. The [O I]λ6300 kinematics in active galactic nuclei (AGNs) cannot be explained only by gas motions due to the gravitational potential of their host galaxies, suggesting that AGN-driven outflows are important to the observed kinematics. While H2 excess also correlates with the fluxes and kinematics of ionized gas (probed by [O III]), the correlation with [O I] is much stronger, suggesting that H2 and [O I] emissions probe the same phase or tightly coupled phases of the wind. We conclude that the excess of H2 emission seen in AGNs is produced by shocks due to AGN-driven outflows and in the same clouds that produce the [O I] emission. Our results provide an indirect detection of neutral and molecular winds and suggest a new way to select galaxies that likely host molecular outflows. Further ground- and space-based spatially resolved observations of different phases of the molecular gas (cold, warm, and hot) are necessary to test our new selection method.