SDSS J134313.15+364457.5: Forming Compact Elliptical through the Merger

Abstract: Scaling relations are fundamental tools for exploring the morphological properties of galaxies and understanding their formation and evolution. Typically, galaxies follow a scaling relation between mass and size, measured by effective radius. However, a compact class of galaxies exists as outliers from this relation, and the origin of these compact galaxies in the local universe remains unclear. In this study, we investigate the compact dwarf galaxy SDSS J134313.15+364457.5 (J1343+3644), which is the result of a merger. Our analysis reveals that J1343+3644 has a half-light radius of 482~pc, significantly smaller than typical galaxies with the same brightness ($M_\text{r} = -19.17$ mag). With a high star-formation rate (SFR) of 0.87~M$_{\sun}$ year$^{-1}$, J1343+3644 is expected to evolve into a compact elliptical galaxy in a few million years. J1343+3644 could, therefore, be a progenitor of a compact elliptical galaxy. The phenomenon happened in early universe, where compact galaxies were common.