Evidence for a chemically differentiated outflow in Mrk 231
Artikel i vetenskaplig tidskrift, 2016

Aims. Our goal is to study the chemical composition of the outflows of active galactic nuclei and starburst galaxies. Methods. We obtained high-resolution interferometric observations of HCN and HCO+ J = 1 -> 0 and J = 2 -> 1 of the ultraluminous infrared galaxy Mrk 231 with the IRAM Plateau de Bure Interferometer. We also use previously published observations of HCN and HCO+ J = 1 -> 0 and J = 3 -> 2, and HNC J = 1 -> 0 in the same source. Results. In the line wings of the HCN, HCO+, and HNC emission, we find that these three molecular species exhibit features at distinct velocities which differ between the species. The features are not consistent with emission lines of other molecular species. Through radiative transfer modelling of the HCN and HCO+ outflow emission we find an average abundance ratio X(HCN) = X(HCO+) greater than or similar to 1000. Assuming a clumpy outflow, modelling of the HCN and HCO+ emission produces strongly inconsistent outflow masses. Conclusions. Both the anti-correlated outflow features of HCN and HCO+ and the different outflow masses calculated from the radiative transfer models of the HCN and HCO+ emission suggest that the outflow is chemically differentiated. The separation between HCN and HCO+ could be an indicator of shock fronts present in the outflow, since the HCN/HCO+ ratio is expected to be elevated in shocked regions. Our result shows that studies of the chemistry in large-scale galactic outflows can be used to better understand the physical properties of these outflows and their effects on the interstellar medium in the galaxy.

driven outflow

starburst galaxy

relativistic jets

herschel-pacs

galaxy markarian 231

vibrationally excited hcn

galaxies: individual: Mrk 231

star-formation

galaxies: evolution

quasars: general

co observations

feedback

dense molecular gas

ISM: jets and

galaxies: active

Författare

Johan Lindberg

NASA Goddard Space Flight Center

Chalmers University of Technology

Susanne Aalto

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

Sebastien Muller

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

Ivan Marti-Vidal

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

Niklas Falstad

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

Francesco Costagliola

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

C. Henkel

King Abdulaziz University

Max Planck-institutet

P. van der Werf

Universiteit Leiden

S. G. Burillo

Observatorio Astronomico Nacional

E. Gonzalez-Alfonso

Universidad de Alcala

Astronomy and Astrophysics

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

Vol. 587 A15

Ämneskategorier

Astronomi, astrofysik och kosmologi

Fundament

Grundläggande vetenskaper

DOI

10.1051/0004-6361/201527457