Global Attenuation in Spiral Galaxies in Optical and Infrared Bands

TL;DR

This study investigates how the intrinsic light attenuation in spiral galaxies varies with their physical properties and orientation, using optical and infrared data from a large galaxy sample to model dust obscuration.

Contribution

It introduces both parametric and non-parametric models for dust attenuation in spiral galaxies based on observable galaxy properties.

Findings

Attenuation is minimal in low-mass, gas-depleted galaxies.

Attenuation peaks in massive, metal-rich, gas-rich galaxies.

A principal component strongly correlates with obscuration amplitude.

Abstract

The emerging light from a galaxy is under the influence of its own interstellar medium, as well as its spatial orientation. Considering a sample of 2,239 local spiral galaxies in optical (SDSS u, g, r, i, and z) and infrared bands (WISE W1, W1), we study the dependency of the global intrinsic attenuation in spiral galaxies on their morphologies, sizes, and spatial inclinations. Reddening is minimal at the extremes of low mass and gas depletion and maximal in galaxies that are relatively massive and metal-rich and still retain substantial gas reserves. A principal component constructed from observables that monitor galaxy mass, relative HI content to old stars, and infrared surface brightness is strongly correlated with the amplitude of obscuration. We determine both a parametric model for dust obscuration and a non-parametric model based on the Gaussian process formalism. An average dust attenuation curve is derived for wavelengths between 0.36 and 4.5 microns.