van der Werf, P. P. and Armus, L. and Lord, S. and Mazzarella, J. (2010) Black hole accretion and star formation as drivers of gas excitation and chemistry in Markarian 231. Astronomy and Astrophysics, 518 . Art. No. L42. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20101130-080627440
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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 H_2O, 3 of OH^+ and one line each of H_2O+, 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 H_2O^+ lines reveals the signature of X-ray driven excitation and chemistry in this region.
|Additional Information:||© 2010 ESO. Received 31 March 2010, Accepted 27 April 2010, Published online 16 July 2010. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. We thank Ewine van Dishoeck, Xander Tielens, and Thomas Nikola for useful discussions. We especially thank Ed Polehampton, Peter Imhof-Davies and Bruce Swinyard for their help with the FTS data processing. JF thanks MPE for its hospitality. The Dark Cosmology Centre is funded by the DNRF. The following institutes have provided hardware and software elements to the SPIRE project: University of Lethbridge, Canada; NAOC, Beijing, China; CEA Saclay, CEA Grenoble and LAM in France; IFSI, Rome, and University of Padua, Italy; IAC, Tenerife, Spain; Stockholm Observatory, Sweden; Cardiff University, Imperial College London, UCL-MSSL, STFCRAL, UK ATC Edinburgh, and the University of Sussex in the UK. Funding for SPIRE has been provided by the national agencies of the participating countries and by internal institute funding: CSA in Canada; NAOC in China; CNES, CNRS, and CEA in France; ASI in Italy; MEC in Spain; Stockholm Observatory in Sweden; STFC in the UK; and NASA in the USA. Additional funding support for some instrument activities has been provided by ESA.|
|Subject Keywords:||galaxies: individual: Mrk 231, galaxies: active, galaxies: ISM, galaxies: nuclei, galaxies: starburst, infrared: galaxies|
|Official Citation:||Black hole accretion and star formation as drivers of gas excitation and chemistry in Markarian 231 P. P. van der Werf, K. G. Isaak, R. Meijerink, M. Spaans, A. Rykala, T. Fulton, A. F. Loenen, F. Walter, A. Weiß, L. Armus, J. Fischer, F. P. Israel, A. I. Harris, S. Veilleux, C. Henkel, G. Savini, S. Lord, H. A. Smith, E. González-Alfonso, D. Naylor, S. Aalto, V. Charmandaris, K. M. Dasyra, A. Evans, Y. Gao, T. R. Greve, R. Güsten, C. Kramer, J. Martín-Pintado, J. Mazzarella, P. P. Papadopoulos, D. B. Sanders, L. Spinoglio, G. Stacey, C. Vlahakis, M. C. Wiedner and E. M. Xilouris A&A 518 L42 (2010) DOI: 10.1051/0004-6361/201014682|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Benjamin Perez|
|Deposited On:||30 Nov 2010 17:29|
|Last Modified:||26 Dec 2012 12:41|
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