Gravitational and mass distribution effects on stationary superwinds I

TL;DR

This paper models how non-uniform mass distributions and gravitational effects influence stationary superwinds in galaxies, providing analytical criteria for their existence and exploring implications for galaxy evolution and metal loss.

Contribution

It introduces analytical formulae to determine when galactic superwinds can occur considering complex mass distributions and gravitational effects, extending previous uniform models.

Findings

Superwind existence depends on mass distribution steepness and concentration.

Gravitational effects can inhibit superwinds under certain conditions.

Results align with observational data and recent numerical simulations.

Abstract

Here, we model the effect of non-uniform dynamical mass distributions and their associated gravitational fields on the stationary galactic superwind solution. We do this by considering an analogue injection of mass and energy from stellar winds and SNe. We give analytical formulae that establish when an outflow is possible and also characterize distinct flow regimes and enrichment scenarios. We also constraint the parameter space by giving approximate limits above which gravitation, self-gravitation and radiative cooling can inhibit the stationary flow. Later, we obtain analytical expressions for the free superwind hydrodynamical profiles. We find that the existence or inhibition of the superwind solution highly depends on the steepness and concentration of the dynamical mass and the mass and energy injection rates, not just in their effective total values. We compare our results with observational data and a recent numerical work that models artificial massive galaxies assuming a uniform distribution of their parameters. Finally, we put our results in the context of the mass-metallicity relationship to discuss observational evidence related to the selective loss of metals from the less massive galaxies and the recent discovery of high-metallicity dwarf spheroidal (dSph) and dwarf elliptical (dE) galaxies.