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
diagnostics
galaxy nuclei
galaxies: ISM
galaxies: starburst
lines
galaxies: active
dense gas
emission
Author
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 L42Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201014682