Photoelectric heating effects on the evolution of luminous disc galaxies

Abstract

ABSTRACT Photoelectric heating (PEH) influences the temperature and density of the interstellar medium (ISM), potentially also affecting star formation. PEH is expected to have a stronger effect on massive galaxies, as they host larger dust reservoirs compared to dwarf systems. Accordingly, in this paper, we study PEH effects in Milky Way-like galaxies using a smoothed particle hydrodynamics code, which self-consistently implements the evolution of the gas, dust, and interstellar radiation field. Dust evolution includes dust formation by stars, destruction by SNe, and growth in dense media. We find that PEH suppresses star formation due to the excess heating that reduces the ISM density. This suppression is seen across the entire range of gas fractions, star-formation recipes, dust models, and PEH efficiencies investigated by our code. The suppression ranges from negligible values to approximately a factor of five depending on the specific implementation. Galaxy models having higher gas fractions experience higher star-formation suppression. The adopted dust model also alters the extent of star-formation suppression. Moreover, when PEH is switched on, galaxy models show higher gas outflow rates and have higher loading factors, indicative of enhanced SNe feedback. In gas-rich models (i.e. a gas fraction of 0.5), we also find that PEH suppresses the formation of disc clumps via violent disc instabilities, and thus suppresses bulge formation via clump migration to the central regions.