ISO LWS mapping of M 83

G.J. Stacey ¹, M.R. Swain ¹, M.J. Barlow ², C.M. Bradford ¹, P. Cox ³, J. Fischer ⁴, S. D. Lord ⁵, M. L. Luhman ⁴, N. Q. Rieu ⁶, H. A. Smith ⁷, S. J. Unger ⁸, & M. G. Wolfire ⁹

¹ Cornell University

² University College, London

³ Institut d'Astrophysique Spatiale, Orsay

⁴ Naval Research Laboratory

⁵ California Institute of Technology

⁶ Observatoire de Paris

⁷ Smithsonian Astrophysical Observatory

⁸ Queen Mary and Westfield College

⁹ University of Maryland

We have mapped the face-on late type barred spiral galaxy M83 in the far-infrared fine-structure lines of [OI] (63 and 146 ), [OIII] 88 , [NII] 122, and [CII] 158 . Our map is laid out on a rectangular 8 x 7 point grid that is nearly fully sampled (45 step size) and covers nearly the entire optical disk. The [CII] and [NII] line are strongly detected over the entire disk. Their ratio indicates that roughly 30% of the observed [CII] emission from the disk arises in low density HII regions. The [OI] 63  line is detected over much of the disk, while the 146  line is detected at about 30% of the pointings. The [OI]/[CII] line ratios are used to estimate the physical conditions of the photodissociated gas. The [OIII] 88  line is locally strong near the spiral arms and bar and signals the harder UV radiation fields associated with very early type (O6 or earlier) stars. We also obtained a full LWS grating scan (43 to 196 ) at the nucleus. At the nucleus we detect the [OIII] 52  line plus the [NIII] 57  line. The [OIII] line ratio indicates the emission from the nucleus is dominated by a low density ( ) ionized medium, while the [OIII] to [NIII] line intensity ratios indicate a near solar abundance ratio.