The central region of spiral galaxies as seen by Herschel. M81, M99 and M100

TL;DR

This study uses Herschel's far-infrared imaging to analyze the central and disk components of spiral galaxies M81, M99, and M100, examining their brightness distribution and implications for galaxy properties.

Contribution

It extends the two-component model of spiral galaxies to longer wavelengths using Herschel data, assessing its validity and impact on understanding galaxy infrared emission.

Findings

The central component remains prominent at Herschel wavelengths.

The two-component model effectively describes the brightness distribution.

Implications for interpreting global far-infrared properties are discussed.

Abstract

With appropriate spatial resolution, images of spiral galaxies in thermal infrared (~10 micron and beyond) often reveal a bright central component, distinct from the stellar bulge, superimposed on a disk with prominent spiral arms. ISO and Spitzer studies have shown that much of the scatter in the mid-infrared colors of spiral galaxies is related to changes in the relative importance of these two components, rather than to other modifications, such as the morphological type or star formation rate, that affect the properties of the galaxy as a whole. With the Herschel imaging capability from 70 to 500 micron, we revisit this two-component approach at longer wavelengths, to see if it still provides a working description of the brightness distribution of galaxies, and to determine its implications on the interpretation of global far-infrared properties of galaxies.