Blueberry galaxies up to 200 Mpc and their optical and infrared properties

TL;DR

This study expands the sample of local blueberry galaxies, analyzing their optical and infrared properties to better understand their extreme star-forming nature and their role as analogs to early Universe dwarf galaxies.

Contribution

It identifies 48 new blueberry galaxies in the southern sky, providing homogeneous measurements of their properties and highlighting their unique star-forming and infrared characteristics.

Findings

Blueberry galaxies are the most intensely star-forming dwarf galaxies locally.

They are intrinsically bluer in visible light but redder in infrared compared to typical SFGs.

They exhibit higher specific star-formation rates, lower metallicities, and more ionized interstellar media.

Abstract

Dwarf highly star-forming galaxies (SFGs) dominated the early Universe and are considered the main driver of its reionization. However, direct observations of these distant galaxies are mainly confined to rest-frame ultraviolet and visible light, limiting our understanding of their complete properties. Therefore, it is still paramount to study their local analogs, the green pea (GP) and blueberry (BB) galaxies. This work aims to expand our knowledge of BBs by identifying a new sample that is closer and in the southern sky. In addition to the already known BBs, this new sample will allow for a statistically significant study of their properties probed by visible and infrared (IR) light. By utilizing the HECATE catalog, which provides photometry and characterization of galaxies, along with data from Pan-STARSS and SDSS, this study selects and analyzes a new sample of BBs. We employed spectral energy distribution fitting to derive homogeneous measurements of star-formation rates and stellar masses. Additionally, we measured emission-line fluxes, including $\rm HeII~\lambda 4686$, through spectral fitting. Through this work, we identified 48 BBs, of which 40 were first recognized as such, with the nearest at 19~Mpc. 14 of the BBs are in the south sky. The BBs tend to be extremely IR red in both WISE $W1-W2$ and $W2-W3$ colors, distinguishing them from typical SFGs. Dwarf SFGs with higher specific star-formation rates tend to have redder IR colors. Blueberry galaxies stand out as the most intensely star-forming sources in the local Universe among dwarf galaxies. They exhibit unique characteristics, such as being intrinsically bluer in visible light, redder in the infrared, and less massive. They also have higher specific star-formation rates, equivalent widths, lower metallicities, and the most strongly ionized interstellar medium compared to typical SFGs and GPs.