Contributed Talk - Splinter SOFIA

Thursday, 14 September 2023, 17:00   (H 3006)

Infrared view of the multi-phase ISM in the nucleus of NGC 253

Andre Beck (1), Vianney Lebouteiller (2), Aaron Bryant (1), Christian Fischer (1), Christof Iserlohe (1), Maja Kazmierczak-Barthel (1), Alfred Krabbe (1), Serina T. Latzko (1), Suzanne C. Madden (2), Juan-Pablo Perez-Beaupuits (3, 4), Lise J. Ramambason (5), and Hans Zinnecker (6)
(1) Deutsches SOFIA Institute, University of Stuttgart; (2) CEA Saclay; (3) MPIfR Bonn; (4) Universidad Catolica de Chile; (5) Institut für Theoretische Physik, Universität Heidelberg; (6) Universidad Autonoma de Chile

We present an analysis of the physical conditions in nucleus of the starburst galaxy NGC253. We used a combined data set from our SOFIA/FIFI-LS observations and from archival data obtained with Spitzer/IRS and Herschel/PACS and SPIRE, providing us with a host of 38 emission lines (26 of which are fine-structure lines) from the mid-infrared to sub-mm range all centered on the nucleus of NGC 253. We analytically calculated the gas density from the [SIII]19/33, [OIII]52/88, and [NII]122/205 line flux ratios, from which we obtained n~100cm-3. We also calculated the Ne/H abundance as a good probe for the metallicity from the ([NeII]13+[NeIII]16)/HuAlpha line flux ratio, from which we determined solar metallicity (see Beck+ 2022 for details). We further used a more sophisticated modeling approach deploying a grid of 544000 Cloudy models (SFGX, see Ramambason+ 2022). Using MULTIGRIS (Lebouteiller & Ramambason 2022), a Bayesian Monte-Carlo code, we calculated probability density distributions of important parameters of the ISM, such as (but mot limited to) metallicity, ionisation parameter, luminosity and temperature of a hypothetical X-ray source. While the results from the analytical approach were confirmed, we also determined an X-ray luminosity, which seems to be comparable to the low-luminosity AGN in the Galaxy. Furthermore, we calculated the dust-mass and the mass of the different gas-phases, as well as the fractional origin of the [CII]158um emission (ionised, neutral atomic and molecular). Lastly, we estimated and compared the SFR from different tracers. The corresponding paper discussing the Cloudy modeling approach and the results has been submitted to A&A.