BreakBRD Galaxies I: Global Properties of Spiral Galaxies with Central Star Formation in Red Disks

TL;DR

This paper introduces a unique sample of spiral galaxies with centrally concentrated star formation, analyzing their properties and discussing their potential evolutionary states compared to typical star-forming and quiescent galaxies.

Contribution

It characterizes a new class of galaxies with truncated disk star formation and compares their properties to other galaxy samples, providing a foundation for future studies.

Findings

Galaxies have properties between high- and low-specific star formation rate samples.

Their morphology and size are distinct from average spiral galaxies.

The sample may be in a quenching phase or exhibiting unusual star formation distribution.

Abstract

We introduce a collection of primarily centrally star-forming galaxies that are selected by disk color to have truncated disk star formation. We show that common explanations for centrally-concentrated star formation -- low stellar mass, bars, and high-density environments, do not universally apply to this sample. To gain insight into our sample, we compare these galaxies to a parent sample of strongly star-forming galaxies and to a parent sample of galaxies with low specific star formation rates. We find that in star formation and color space from ultraviolet to the infrared these galaxies either fall between the two samples or agree more closely with galaxies with high-specific star formation rates. Their morphological characteristics also lie between high- and low-specific star formation rate galaxies, although their Petrosian radii agree well with that of the low-specific star formation rate parent sample. We discuss whether this sample is likely to be quenching or showing an unusual star-formation distribution while continuing to grow through star formation. Future detailed studies of these galaxies will give us insights into how the local conditions within a galaxy balance environmental influence to govern the distribution of star formation. In this first paper in a series, we describe the global properties that identify this sample as separate from more average spiral galaxies, and identify paths forward to explore the underlying causes of their differences.