2011/07/19 by A. V. Zasov, Zasov, A. V., O. V. Abramova +1
Engineering · Physics and Astronomy · #Astrophysics and Star Formation Studies #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Phase Equilibria and Thermodynamics
paper · pdf · doi:10.48550/arxiv.1107.3723
openalex publication_date 2011/07/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We calculated the radial profiles of the azimuthally averaged midplane gas volume density ρg for 11 high surface brightness (HSB) spiral galaxies, 7 low surface brightness (LSB) galaxies and 3 S0 galaxies assuming their gaseous layers to be in the equilibrium state in the plane of marginally stable stellar discs. We compared the surface star formation rate (ΣSFR) and star formation efficiency (SFE=ΣSFR/Σgas) with ρg and stellar surface density Σs assuming the latter to be proportional to disc surface brightness. Both HSB and LSB galaxies follow a single sequence ΣSFR-ρg and SFE-Σs or SFE-ρs. It means that the conditions of star formation are similar in the outer discs of normal spiral galaxies and in the inner regions of LSB galaxies if their stellar discs have similar densities. The relationship between SFE and ρs is close to the law SFE ∼ ρs1/2 expected in the theoretical model of self-regulated star formation proposed by Ostriker et al.\citeOstrikerAll10. The alternative explanation is to propose that SFE is proportional to a frequency of vertical oscillation of gas clouds around the disc midplane. In the most rarified regions of LSB galaxies the efficiency of star formation is nearly independent on gas and stellar disc densities being higher in the mean than it is expected from the extrapolation of the power law fit for HSB sample galaxies. Evidently in these regions with extremely low ρg SFE depends on local density fluctuations rather than on the azimuthally averaged disc parameters.