Turbulent and fast motions of H2 gas in active galactic nuclei

• Published in: Astronomy and astrophysics (Berlin) Vol. 533
• Main Authors: Dasyra, K. M., Combes, F.
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences 2011
• Subjects: Astronomy; Astrophysics; Earth, ocean, space; Exact sciences and technology; galaxies: active; galaxies: nuclei; infrared: galaxies; ISM: jets and outflows; ISM: kinematics and dynamics; line: profiles; Physics; Interacting galaxies; Spectroscopy; Cold gas; ISM: jets and outflows; Line shape; infrared: galaxies; Mass loss; Loss rate; Molecular gas; Velocity dispersion; ISM: kinematics and dynamics -galaxies: nuclei; Active galaxies; Star formation; Dynamics; galaxies: active; Active galaxy nuclei; line: profiles; Kinematics; Galaxy nuclei; Tidal tail; Jets; Line wing; Infrared galaxies
• ISSN: 0004-6361; 1432-0746; 1432-0756
• DOI: 10.1051/0004-6361/201117730

Querying the Spitzer archive for optically-selected active galactic nuclei (AGN) observed in high-resolution-mode spectroscopy, we identified radio and/or interacting galaxies with highly turbulent motions of H2 gas at a temperature of a few hundred Kelvin. Unlike all other AGN that have unresolved H2 line profiles at a spectral resolution of  ~600, 3C 236, 3C 293, IRAS 09039+0503, MCG-2-58-22 and Mrk 463E have intrinsic velocity dispersions exceeding 200 km s-1 for at least two of the rotational S0, S1, S2, and S3 lines. In a sixth source, 4C 12.50, a blue wing was detected in the S1 and S2 line profiles, indicating the presence of a warm molecular gas component moving at  − 640 km s-1 with respect to the bulk of the gas at systemic velocity. Its mass is 5.2  ×  107 M⊙, accounting for more than one fourth of the H2 gas at 374 K, but less than 1% of the cold H2 gas computed from CO observations. Because no diffuse gas component of 4C 12.50 has been observed to date to be moving at more than 250 km s-1 from systemic velocity, the H2 line wings are unlikely to be tracing gas in shock regions along the tidal tails of this merging system. They can instead be tracing gas driven by a jet or entrained by a nuclear outflow, which is known to emerge from the west nucleus of 4C 12.50. It is improbable that such an outflow, with an estimated mass loss rate of 130 M⊙ yr-1, entirely quenches the star formation around this nucleus.