Midplane Gas Density and the Schmidt Law

TL;DR

This study calculates midplane gas densities in spiral and LSB galaxies considering self-gravity and dark halo effects, and compares these densities with star formation rates to test the universality of the Schmidt law.

Contribution

It provides a self-consistent method to determine gas densities in galaxy disks, incorporating dark halo influence, and evaluates the Schmidt law's applicability across different galaxy types.

Findings

Midplane gas densities are consistent with star formation rates.

The Schmidt law's power-law index n is examined across galaxy types.

Dark halo effects significantly influence gas density calculations.

Abstract

The thickness of isothermal gaseous layers and their midplane volume densities \rho_{gas}(R) were calculated for several spiral and LSB galaxies by solving the self-consistent equilibrium equations for gaseous discs embedded into a stellar one. The self-gravity of the gas and influence of dark halo on the disk thickness were taken into account. The resulting midplane volume densities of spiral galaxies were compared with the azimuthally averaged star formation rate SFR to verify the feasibility and universality of the Schmidt law SFR ~ \rho_{gas}^n.