Probing the molecular interstellar medium of M82 with Herschel-SPIRE spectroscopy

P. Panuzzo , N. Rangwala , A. Rykala , K. G. Isaak , J. Glenn , C. D. Wilson , R. Auld , M. Baes , M. J. Barlow , G. J. Bendo , J. J. Bock , A. Boselli (1) , M. Bradford , V. Buat , N. Castro-Rodriguez , P. Chanial , S. Charlot , L. Ciesla , D. L. Clements , A. Cooray , D. Cormier , L. Cortese , J. I. Davies , E. Dwek , S. A. Eales , D. Elbaz , T. Fulton , M. Galametz , F. Galliano , W. K. Gear , H. L. Gomez , M. Griffin , S. Hony , L. R. Levenson , N. Lu , S. Madden , B. O'Halloran , K. Okumura , S. Oliver , M. J. Page , A. Papageorgiou , T. J. Parkin , I. Perez-Fournon , M. Pohlen , E. T. Polehampton , E. E. Rigby , H. Roussel , N. Sacchi , M. Sauvage , B. Schulz , M. R. P. Schirm , M. W. L. Smith , L. Spinoglio , J. A. Stevens , S. Srinivasan , M. Symeonidis , B. Swinyard , M. Trichas , M. Vaccari , L. Vigroux , H. Wozniak , G. S. Wright , W. W. Zeilinger

1 LAM - Laboratoire d'Astrophysique de Marseille

We present the observations of the starburst galaxy M82 taken with the Herschel SPIRE Fourier-transform spectrometer. The spectrum (194-671 mu m) shows a prominent CO rotational ladder from J = 4-3 to 13-12 emitted by the central region of M82. The fundamental properties of the gas are well constrained by the high J lines observed for the first time. Radiative transfer modeling of these high-S/N (12)CO and (13)CO lines strongly indicates a very warm molecular gas component at similar to 500 K and pressure of similar to 3 x 10(6) K cm(-3), in good agreement with the H(2) rotational lines measurements from Spitzer and ISO. We suggest that this warm gas is heated by dissipation of turbulence in the interstellar medium (ISM) rather than X-rays or UV flux from the straburst. This paper illustrates the promise of the SPIRE FTS for the study of the ISM of nearby galaxies.

Domaines: Astrophysique [astro-ph]

P. Panuzzo, N. Rangwala, A. Rykala, K. G. Isaak, J. Glenn, et al.. Probing the molecular interstellar medium of M82 with Herschel-SPIRE spectroscopy. Astronomy and Astrophysics - A&A, 2010, 518, ⟨10.1051/0004-6361/201014558⟩. ⟨hal-01438946⟩