Black hole accretion and star formation as drivers of gas excitation and chemistry in Markarian 231
Paul P. van der Werf
(1)
,
K. G. Isaak
(2)
,
R. Meijerink
(1)
,
Marco Spaans
(3)
,
A. Rykala
(2)
,
Trevor Fulton
(4)
,
A. F. Loenen
(1)
,
F. Walter
(5)
,
Achim Weiss
(6)
,
Lee Armus
(7)
,
J. Fischer
(8)
,
Frank P. Israel
(1)
,
A. I. Harris
(9)
,
Sylvain Veilleux
(9)
,
C. Henkel
(6)
,
Giorgio Savini
(10)
,
Steven D. Lord
(11)
,
Howard A. Smith
(12)
,
Eduardo González-Alfonso
(13)
,
David A. Naylor
(14)
,
Susanne Aalto
(15)
,
Vassilis Charmandaris
(16)
,
Kalliopi Dasyra
(17)
,
Aaron S. Evans
(18)
,
Yu Gao
(19)
,
T. R. Greve
(5)
,
Rolf Güsten
(6)
,
Carsten Kramer
(20)
,
Jesus Martin-Pintado
(21)
,
Joseph M. Mazzarella
(11)
,
P. P. Papadopoulos
(22)
,
David B. Sanders
(23)
,
Luigi Spinoglio
(24)
,
Gordon J. Stacey
(25)
,
C. Vlahakis
(1)
,
Martina Wiedner
(26)
,
E. M. Xilouris
(27)
1
Leiden Observatory [Leiden]
2 Cardiff University
3 University of Groningen [Groningen]
4 BSS - Blue Sky Spectroscopy
5 MPIA - Max-Planck-Institut für Astronomie
6 MPIfR - Max-Planck-Institut für Radioastronomie
7 SSC - Spitzer Science Center, California Institute of Technology
8 Remote Sensing Division, Naval Research laboratory
9 Department of Astronomy, University of Maryland
10 UCL - University College of London [London]
11 IPAC - Infrared Processing Analysis Center, California Institute of Technology
12 CfA - Harvard-Smithsonian Center for Astrophysics
13 UAH - Universidad de Alcalá - University of Alcalá
14 Department of Physics, University of Lethbridge
15 Department of Radio and Space Science, Chalmers University of Technology
16 Crete Center for Theoretical Physics, Department of Physics
17 CEA - Commissariat à l'énergie atomique et aux énergies alternatives
18 Astronomy Department, University of Virginia, Charlottesville
19 Purple Mountain Observatory
20 IRAM - Instituto de Radio Astronomía Milimétrica
21 Departamento de Astrofisica Molecular e Infrarroja-Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científica (CSIC)
22 Rheinische Friedrich-Wilhelms-Universität Bonn
23 Institute for Astronomy, University of Hawaii
24 IFSI - Istituto di Fisica dello Spazio Interplanetario
25 Department of Astronomy, Cornell University
26 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
27 Institute of Astronomy and Astrophysics, National Observatory of Athens
2 Cardiff University
3 University of Groningen [Groningen]
4 BSS - Blue Sky Spectroscopy
5 MPIA - Max-Planck-Institut für Astronomie
6 MPIfR - Max-Planck-Institut für Radioastronomie
7 SSC - Spitzer Science Center, California Institute of Technology
8 Remote Sensing Division, Naval Research laboratory
9 Department of Astronomy, University of Maryland
10 UCL - University College of London [London]
11 IPAC - Infrared Processing Analysis Center, California Institute of Technology
12 CfA - Harvard-Smithsonian Center for Astrophysics
13 UAH - Universidad de Alcalá - University of Alcalá
14 Department of Physics, University of Lethbridge
15 Department of Radio and Space Science, Chalmers University of Technology
16 Crete Center for Theoretical Physics, Department of Physics
17 CEA - Commissariat à l'énergie atomique et aux énergies alternatives
18 Astronomy Department, University of Virginia, Charlottesville
19 Purple Mountain Observatory
20 IRAM - Instituto de Radio Astronomía Milimétrica
21 Departamento de Astrofisica Molecular e Infrarroja-Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científica (CSIC)
22 Rheinische Friedrich-Wilhelms-Universität Bonn
23 Institute for Astronomy, University of Hawaii
24 IFSI - Istituto di Fisica dello Spazio Interplanetario
25 Department of Astronomy, Cornell University
26 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
27 Institute of Astronomy and Astrophysics, National Observatory of Athens
Résumé
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.