The Reach of Stars: Connecting the Physical Processes in the ISM with Galaxy Evolution

• Applicants: Dr. Kathryn Kreckel; Dr. Eva Schinnerer
• Subject Area: Astrophysics and Astronomy
• Term: from 2011 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 203350957

To understand galaxies, we must first understand the physical processes that regulate their evolution: the cooling of the interstellar medium (ISM) to form stars, and the heating of the ISM by the stars that form. The Herschel Infrared Space Observatory is now enabling major breakthroughs in the understanding of these physical processes, providing spatially resolved maps of the interstellar dust and the atomic and molecular emission within galaxies, thus tracing the heating and cooling of the ISM, respectively. KINGFISH, a legacy dataset of 61 nearby galaxies with unprecedented sensitivity and resolution, is ideally suited for investigating the role physical conditions (i.e. gas metallicity and excitation) play in this cycle, and determining the relevant spatial scales. In the first funding period we investigated the cold dust properties on 200-700 pc scales, and found a connection between the dust column traced by optical attenuation and the dust mass traced by far-IR emission, with an improved correlation on small physical scales. We also mapped the physical conditions in a starburst driven galactic wind, tracing the outflow from the launching region at the disk center out to 2.5 kpc above the galaxy disk. We propose here to complete our project tracing 'The Reach of Stars' at the spatial scales relevant in the ISM of nearby galaxies. Following our original dust study, we will connect the physical properties of the cold dust with its internal geometry at small (100 pc) spatial scales. In a novel approach, we will investigate the excitation conditions using emission lines from all three gas phases (ionized, neutral and molecular) and, using metallicity as an evolutionary tracer, connect these physical conditions in the dust and gas to galaxy evolution. We request funding for one postdoc and one student for 3 years to successfully complete this project.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1573: Physics of the Interstellar Medium