Black hole accretion and star formation as drivers of gas excitation and chemistry in Markarian 231
Journal article, 2010

We present a full high resolution SPIRE FTS spectrum of the nearby ultraluminous infrared galaxy Mrk 231. In total 25 lines are detected, including CO J = 5-4 through J = 13-12, 7 rotational lines of H2O, 3 of OH+ and one line each of H2O+, CH+, and HF. We find that the excitation of the CO rotational levels up to J = 8 can be accounted for by UV radiation from star formation. However, the approximately flat luminosity distribution of the CO lines over the rotational ladder above J = 8 requires the presence of a separate source of excitation for the highest CO lines. We explore X-ray heating by the accreting supermassive black hole in Mrk 231 as a source of excitation for these lines, and find that it can reproduce the observed luminosities. We also consider a model with dense gas in a strong UV radiation field to produce the highest CO lines, but find that this model strongly overpredicts the hot dust mass in Mrk 231. Our favoured model consists of a star forming disk of radius 560 pc, containing clumps of dense gas exposed to strong UV radiation, dominating the emission of CO lines up to J = 8. X-rays from the accreting supermassive black hole in Mrk 231 dominate the excitation and chemistry of the inner disk out to a radius of 160 pc, consistent with the X-ray power of the AGN in Mrk 231. The extraordinary luminosity of the OH+ and H2O+ lines reveals the signature of X-ray driven excitation and chemistry in this region.

galaxies: individual: Mrk 231

galaxies: nuclei

infrared: galaxies


galaxy nuclei

galaxies: ISM

galaxies: starburst


galaxies: active

dense gas



P.P. van der Werf

Leiden University

K. Isaak

Cardiff University

European Space Research and Technology Centre (ESA ESTEC)

R. Meijerink

Leiden University

M. Spaans

University of Groningen

A. Rykala

Cardiff University

T. Fulton

Blue Sky Spectroscopy

A. F. Loenen

Leiden University

F. Walter

Max Planck Society

A. Weiss

Max Planck Society

L. Armus

Spitzer Science Center

J. Fischer

Naval Research Laboratory

F. P. Israel

Leiden University

A. I. Harris

University of Maryland

S. Veilleux

University of Maryland

C. Henkel

Max Planck Society

G. Savini

University College London (UCL)

S. Lord

California Institute of Technology (Caltech)

H. A. Smith

Harvard-Smithsonian Center for Astrophysics

E. Gonzalez-Alfonso

University of Alcalá

D. A. Naylor

University of Lethbridge

Susanne Aalto

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

V. Charmandaris

University of Crete

K. M. Dasyra

The French Alternative Energies and Atomic Energy Commission (CEA)

A. Evans

University of Virginia

National Radio Astronomy Observatory

Y. Gao

Chinese Academy of Sciences

T. R. Greve

Niels Bohr Institute

Max Planck Society

R. Güsten

Max Planck Society

C. Kramer

Institut de Radioastronomie Millimétrique (IRAM)

J. Martin-Pintado

CSIC - Instituto de Estructura de la Materia (IEM)

J. Mazzarella

California Institute of Technology (Caltech)

P. P. Papadopoulos

Argelander-Institut für Astronomie

D. B. Sanders

University of Hawaii

L. Spinoglio

Consiglo Nazionale Delle Richerche

G. Stacey

Cornell University

C. Vlahakis

Leiden University

M. C. Wiedner

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

E. M. Xilouris

National Observatory of Athens

Astronomy and Astrophysics

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

Vol. 518 Article Number: L42 L42

Subject Categories

Astronomy, Astrophysics and Cosmology



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