Dusty Winds: Extraplanar PAH Features of Nearby Galaxies

TL;DR

This study uses Spitzer IRAC images to analyze extraplanar PAH emission in 16 nearby galaxies with winds, revealing correlations with star formation activity and providing insights into dust distribution in galactic outflows.

Contribution

It is the first detailed investigation of extraplanar PAH features in local galaxies, linking PAH emission to star formation and wind properties.

Findings

Extraplanar PAH features are detected up to 6 kpc from galaxy planes.

A linear correlation exists between extraplanar PAH emission and total infrared flux.

Star formation rate surface density influences the height of PAH emission.

Abstract

Recent observations have shown the presence of dust and molecular material in galactic winds, but relatively little is known about the distribution of these outflow components. To shed some light on this issue, we have used IRAC images from the Spitzer Space Telescope archive to investigate polycyclic aromatic hydrocarbon (PAH) emission from a sample of 16 local galaxies with known winds. Our focus on nearby sources (median distance 8.6 Mpc) has revealed detailed PAH structure in the winds and allowed us to measure extraplanar PAH emission. We have identified extraplanar PAH features on scales of ~ 0.8 - 6.0 kpc. We find a nearly linear correlation between the amount of extraplanar PAH emission and the total infrared flux, a proxy for star formation activity in the disk. Our results also indicate a correlation between the height of extraplanar PAH emission and star formation rate surface density, which supports the idea of a surface density threshold on the energy or momentum injection rate for producing detectable extraplanar wind material.