Active Galaxy Science with the Line Emission Mapper: The Case for High-Resolution Soft X-ray Spectroscopy

Abstract: This white paper discusses the breadth of science related to active galactic nuclei (AGN) and associated phenomena to be enabled by a mission with microcalorimeter energy resolution in the soft X-ray band, a large collecting area, and wide-field imaging. Such a mission, the Line Emission Mapper (LEM), has been proposed to NASA's 2023 Astrophysics Probe Explorer call. While the science pillars of the PI-led part of the mission focus on galaxy evolution, the PI-led LEM All-Sky Survey (LASS) and General Observer/Investigator opportunities will enable vital discoveries for AGN science in the critical soft X-ray band.