Dwarf and Intermediate-Mass Galaxies in MaNGA: Evidence for Different Evolutionary Trends

TL;DR

This study analyzes how galaxy morphology, star formation, and environment influence galaxy evolution across a wide mass range, revealing distinct evolutionary trends for dwarf and intermediate-mass galaxies.

Contribution

It provides a unified analysis of galaxy evolution across stellar masses, highlighting the importance of separating dwarf and intermediate-mass galaxies for accurate interpretation.

Findings

Dwarf galaxies are mostly star-forming with weak environmental dependence.

Intermediate-mass galaxies show clearer environmental quenching trends.

Dwarf ellipticals and S0s have younger stellar populations than their intermediate-mass counterparts.

Abstract

We investigate the interplay between morphology, specific star formation rate (sSFR), and local environment using a sample of 7,408 galaxies from the SDSS-IV MaNGA survey. Our analysis spans stellar masses from dwarf to massive galaxies, enabling a unified view of how stellar mass and environment regulate galaxy evolution. Galaxies are classified by morphology (ellipticals (E), lenticulars (S0s), early-type spirals (ETS), and late-type spirals (LTS)) and local environmental density, with star formation activity traced using sSFR. Low-mass galaxies ($\log (M_{\star}/M_{\odot}) < 10$) are predominantly star-forming and dominated by LTS, whereas high-mass galaxies ($\log (M_{\star}/M_{\odot}) \geq 10$) are dominated by ETS and are largely quenched. By separating dwarf ($\log (M_{\star}/M_{\odot}) \leq 9.5$) and intermediate-mass galaxies ($9.5 < \log (M_{\star}/M_{\odot}) < 10$), we find that dwarf galaxies remain predominantly star-forming with only weak environmental dependence, whereas intermediate-mass galaxies exhibit clearer environmental trends toward quenching. Using the D4000 index as a tracer of long-term stellar population aging, we further show that dwarf E and S0s host systematically younger stellar populations than their intermediate-mass counterparts, implying reduced quenching efficiency and more gradual environmental processing in the dwarf regime. This distinction is not evident among spiral galaxies, whose stellar population properties are comparatively insensitive to the dwarf versus non-dwarf classification. Overall, these results indicate that the commonly defined low-mass galaxy population is not homogeneous and that dwarf and intermediate-mass galaxies show systematically different evolutionary trends. Treating them separately is therefore essential for interpreting galaxy evolution in the low-mass regime.