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HIFI spectroscopy of low-level water transitions in M 82

Weiß, A. and Lord, S. (2010) HIFI spectroscopy of low-level water transitions in M 82. Astronomy and Astrophysics, 521 . Art. No. L1. ISSN 0004-6361.

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We present observations of the rotational ortho-water ground transition, the two lowest para-water transitions, and the ground transition of ionised ortho-water in the archetypal starburst galaxy M 82, performed with the HIFI instrument on the Herschel Space Observatory. These observations are the first detections of the para-H_2O(1_(11)–0_(00)) (1113 GHz) and ortho-H_2O^+(1_(11)–0_(00)) (1115 GHz) lines in an extragalactic source. All three water lines show different spectral line profiles, underlining the need for high spectral resolution in interpreting line formation processes. Using the line shape of the para-H_2O(1_(11)–0_(00)) and ortho-H_2O^+(1_(11)–0_(00)) absorption profile in conjunction with high spatial resolution CO observations, we show that the (ionised) water absorption arises from a ~2000 pc^2 region within the HIFI beam located about ~50 pc east of the dynamical centre of the galaxy. This region does not coincide with any of the known line emission peaks that have been identified in other molecular tracers, with the exception of HCO. Our data suggest that water and ionised water within this region have high (up to 75%) area-covering factors of the underlying continuum. This indicates that water is not associated with small, dense cores within the ISM of M 82 but arises from a more widespread diffuse gas component.

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Weiß, A.0000-0003-4678-3939
Additional Information:© 2010 ESO. Received 28 May 2010, Accepted 1 July 2010, Published online 01 October 2010. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with participation from NASA. HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada, and the United States under the leadership of SRON Netherlands Institute for Space Research, Groningen, The Netherlands, and with major contributions from Germany, France, and the US. Consortium members are: Canada: CSA, U. Waterloo; France: CESR, LAB, LERMA, IRAM; Germany: KOSMA, MPIfR, MPS; Ireland: NUI Maynooth; Italy: ASI, IFSI-INAF, Osservatorio Astrofisico di Arcetri – INAF; Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio Astronmico Nacional (IGN), Centro de Astrobiologia (CSIC-INTA). Sweden: Chalmers University of Technology – MC2, RSS & GARD; Onsala Space Observatory; Swedish National Space Board, Stockholm University – Stockholm Observatory; Switzerland: ETH Zurich, FHNW; USA: Caltech, JPL, NHSC. A.H., S.L. acknowledge support for this work by NASA through an award issued by JPL/Caltech. J.M.P. and J.R. have been partially supported by MCINN grant ESP2007- 65812-CO2-01. RSz acknowledges support from grant No. 203 393334 from the Polish MNiSW.
Funding AgencyGrant Number
Ministerio de Ciencia e Innovación (MCINN) (Spain)ESP2007-65812-CO2-01
Ministerstwo Nauki i Szkolnictwa Wyższego (MNiSW) (Poland)203 393334
Subject Keywords:line: formation – galaxies: ISM – ISM: molecules – galaxies: individual: M82 – infrared: galaxies – submillimeter: galaxies
Record Number:CaltechAUTHORS:20110110-110928663
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Official Citation:HIFI spectroscopy of low-level water transitions in M 82 A. Weiß, M. A. Requena-Torres, R. Güsten, S. García-Burillo, A. I. Harris, F. P. Israel, T. Klein, C. Kramer, S. Lord, J. Martin-Pintado, M. Röllig, J. Stutzki, R. Szczerba, P. P. van der Werf, S. Philipp-May, H. Yorke, M. Akyilmaz, C. Gal, R. Higgins, A. Marston, J. Roberts, F. Schlöder, M. Schultz, D. Teyssier, N. Whyborn and H. J. Wunsch A&A 521 L1 (2010) DOI: 10.1051/0004-6361/201015078
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21664
Deposited By: Benjamin Perez
Deposited On:10 Jan 2011 19:26
Last Modified:03 Oct 2019 02:27

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