CPL - Chalmers Publication Library
| Utbildning | Forskning | Styrkeområden | Om Chalmers | In English In English Ej inloggad.

Evidence for a chemically differentiated outflow in Mrk 231

Johan Lindberg ; Susanne Aalto (Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium) ; Sebastien Muller (Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium) ; Ivan Marti-Vidal (Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium) ; Niklas Falstad (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik) ; Francesco Costagliola (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik) ; C. Henkel ; P. van der Werf ; S. Garcia-Burillo ; E. Gonzalez-Alfonso
Astronomy & Astrophysics (1432-0746). Vol. 587 (2016),
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: galaxies: individual: Mrk 231, galaxies: active, galaxies: evolution, quasars: general, ISM: jets and, vibrationally excited hcn, dense molecular gas, galaxy markarian 231, relativistic jets, starburst galaxy, co observations, driven outflow, star-formation, herschel-pacs, feedback



Denna post skapades 2016-05-04. Senast ändrad 2016-05-11.
CPL Pubid: 235944

 

Läs direkt!


Länk till annan sajt (kan kräva inloggning)