SDSS-IV MaNGA: Blueberry Candidates Associated with LSB Galaxies $-$ Merger or Tidal Dwarf Systems ?

TL;DR

This study discovers two compact, low-mass starburst galaxies called blueberries near LSB galaxies, analyzing their metallicity differences and dynamics to assess if they are merger remnants or tidal dwarf galaxies.

Contribution

First identification of blueberry galaxies associated with LSBs using MaNGA data, with detailed analysis of their metallicity, structure, and merger status.

Findings

Blueberries are the lowest stellar mass among known local blueberries.

Significant metallicity difference (~0.5 dex) between blueberries and LSBs.

Blueberries are unlikely to survive tidal forces, indicating merger remnants.

Abstract

We report here our finding of two new blueberry galaxies using optical IFU spectroscopic data from the MaNGA survey. Both the blueberries are found to be compact ($\leq$ $1 - 2$ kpc) starburst systems located at the outskirts of Low Surface Brightness (LSB) galaxies. Our blueberries have the lowest stellar masses $\sim$ 10$^{5}$ M$_{\odot}$ amongst the locally known blueberry galaxies. We find a significantly large mean metallicity difference ($\sim$ 0.5 dex) between the blueberry sources and their associated LSBs. Moreover, the radial metallicity gradients in our blueberries are also different than their respective LSBs - suggesting that these had significantly different metallicity histories. The likelihood of survival of these blueberries as TDGs is analyzed based on their structural and kinematic properties. Our analysis shows that although the two blueberries are stable against internal motions, they would not have survived against the tidal force of the host galaxy. Based on the velocity difference between the host LSBs and the blueberries, it appears that they are compact, starburst systems in their advanced stage of merger with these LSBs situated in a dense environment. Implications of our findings are discussed.