AR 17051 (Archival Research)

Mon Jul 15 04:39:04 GMT 2024

Principal Investigator: Nicolas Lehner
PI Institution: University of Notre Dame
Investigators (xml)

Title: A ULLYSES Survey of the Magellanic Clouds: a Laboratory for the Physics of Interfaces between Hot and Cold Gas
Cycle: 30

The interface layers between hot and cool gas play a critical role in regulating the physical processes in galaxies and are crucial to theories of galaxy formation and evolution. The high ions OVI, NV, CIV, SiIV are the best probes of these interfaces. Yet their core properties are still poorly constrained because we have little direct observations of their dependence on the physical environments and metallicities. We propose to use the ULLYSES UV spectra of 239 hot stars to produce the first comprehensive analysis of the highly ionized gas in the LMC and SMC galaxies with a metallicity of 0.50 and 0.25 solar. The ULLYSES dataset is uniquely suited for this analysis owing to its uniformly high quality spectra. In addition, there is a wealth of ancillary data in the LMC and SMC, allowing for the characterization of the physical galactic environments at an unprecedented level of detail. Our program will enable the following key science goals: 1) we will characterize unambiguously for the first time the microphysics properties of the highly ionized gas in interface layers; 2) we will determine variations in these properties as a function of galactic environment and metallicity; and 3) we will help interpret low-resolution spectra of high ions in high-redshift objects by creating equivalent spectra by means of stacking and smoothing ULLYSES spectra covering prominent structures. We will release high-level data products, including a new classification scheme of the interstellar environment probed by each ULLYSES LMC/SMC target. Our program will pave a new path to understanding how the highly ionized gas in interface layers shapes galaxies.