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.

emission

infrared: galaxies

lines

galaxy nuclei

galaxies: starburst

dense gas

diagnostics

galaxies: individual: Mrk 231

galaxies: ISM

galaxies: nuclei

galaxies: active

Author

P.P. van der Werf

Leiden University

K. Isaak

Cardiff University

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 Institute

A. Weiss

Max Planck Institute

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 Institute

G. Savini

University College London (UCL)

S. Lord

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

Panepistimio Kritis

K. M. Dasyra

The French Alternative Energies and Atomic Energy Commission (CEA)

A. Evans

University of Virginia

National Radio Astronomy Observatory

Y. Gao

Purple Mountain Observatory Chinese Academy of Sciences

T. R. Greve

Niels Bohr Institute

Max Planck Institute

R. Güsten

Max Planck Institute

C. Kramer

Instituto de Radioastronomia Milimetrica

J. Martin-Pintado

CSIC - Instituto de Estructura de la Materia (IEM)

J. Mazzarella

CalTech

P. P. Papadopoulos

Argelander-Institut für Astronomie

D. B. Sanders

University of Hawaii at Manoa

L. Spinoglio

Consiglio Nazionale delle Ricerche

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 L42

Subject Categories

Astronomy, Astrophysics and Cosmology

DOI

10.1051/0004-6361/201014682