Detection of HCN, HCO+, and HNC in the Mrk 231 molecular outflow. Dense molecular gas in the AGN wind
Journal article, 2012

We obtained high-resolution (1.''55 × 1.''28) observations of HCN, HCO+, HNC 1-0 and HC3N 10-9 of the ultraluminous galaxy (ULIRG) Mrk 231 with the IRAM Plateau de Bure Interferometer. Results: We detect luminous emission from HCN, HCO+ and HNC 1-0 in the QSO ULIRG Mrk 231. All three lines show broad line wings - which are particularly prominent for HCN. Velocities are found to be similar ( ≈ ± 750 km s-1) to those found for CO 1-0. This is the first time bright HCN, HCO+ and HNC emission has been detected in a large-scale galactic outflow. We find that both the blue- and red-shifted line wings are spatially extended by at least 0.''75 (>700 pc) in a north-south direction. The line wings are brighter (relative to the line center intensity) in HCN than in CO 1-0 and line ratios suggest that the molecular outflow consists of dense (n > 104 cm-3) and clumpy gas with a high HCN abundance X(HCN) > 10-8. These properties are consistent with the molecular gas being compressed and fragmented by shocks in the outflow. Alternatively, HCN is instead pumped by mid-IR continuum, but we propose that this effect is not strong for the spatially extended outflowing gas. In addition, we find that the rotation of the main disk, in east-west direction, is also evident in the HCN, HCO+ and HNC line emission. An unexpectedly bright HC3N 10-9 line is detected inside the central 400 pc of Mrk 231. This HC3N emission may emerge from a shielded, dust-enshrouded region within the inner 40-50 pc where the gas is heated to high temperatures (200-300 K) by the AGN.

radio lines: ISM

ISM: molecules

galaxies: active

quasars: general

galaxies: individual: Mrk 231

galaxies: evolution

Author

Susanne Aalto

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

S. G. Burillo

Spanish National Observatory (OAN)

Sebastien Muller

Chalmers, Earth and Space Sciences, Onsala Space Observatory

J.M. Winters

Institut de RadioAstronomie Millimetrique (IRAM)

P. van der Werf

Leiden University

C. Henkel

Max Planck Institute

King Abdulaziz University

Francesco Costagliola

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

R. Neri

Institut de RadioAstronomie Millimetrique (IRAM)

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 537 44-51 A44

Subject Categories

Astronomy, Astrophysics and Cosmology

Roots

Basic sciences

DOI

10.1051/0004-6361/201117919

More information

Latest update

9/6/2018 1