Disk heating agents across the Hubble sequence

TL;DR

This study investigates how the shape of the velocity ellipsoid varies across different galaxy types, revealing a strong correlation with galaxy morphology and providing insights into disk heating mechanisms.

Contribution

It extends previous analyses to include late-type spirals, confirming a significant correlation between velocity ellipsoid shape and galaxy properties, aiding understanding of disk heating agents.

Findings

Confirmed a tight correlation between velocity ellipsoid shape and galaxy morphology.

Identified trends linking velocity dispersions with galaxy color, gas density, and spiral structure.

Provided observational clues to disk heating mechanisms in external galaxies.

Abstract

We measure the shape of the velocity ellipsoid in two late-type spiral galaxies (Hubble types Sc and Scd) and combine these results with our previous analyses of six early-type spirals (Sa to Sbc) to probe the relation between galaxy morphology and the ratio of the vertical and radial dispersions. We confirm at much higher significance (99.9 percent) our prior detection of a tight correlation between these quantities. We explore the trends of the magnitude and shape of the velocity ellipsoid axes with galaxy properties (colour, gas surface mass density, and spiral arm structure). The observed relationships allow for an observational identification of the radial and vertical disk heating agents in external disk galaxies.