SDSS-IV MANGA: Spatially Resolved Star Formation Main Sequence and LI(N)ER Sequence

TL;DR

This study reveals that the local relation between star formation rate and stellar mass surface density on kiloparsec scales underpins the global star-forming main sequence, and identifies a distinct LI(N)ER sequence in quiescent galaxies.

Contribution

It demonstrates the spatially resolved relation between H_alpha emission and stellar mass density, linking local and global star formation, and characterizes the LI(N)ER sequence in quiescent galaxies.

Findings

Star-forming galaxies show a strong Sigma_SFR–Sigma_star correlation on kpc scales.

About 20% of quiescent galaxies exhibit residual star formation in outer regions.

A tight Sigma_H_alpha–Sigma_star correlation defines the LI(N)ER sequence in quiescent galaxies.

Abstract

We present our study on the spatially resolved H_alpha and M_star relation for 536 star-forming and 424 quiescent galaxies taken from the MaNGA survey. We show that the star formation rate surface density (Sigma_SFR), derived based on the H_alpha emissions, is strongly correlated with the M_star surface density (Sigma_star) on kpc scales for star- forming galaxies and can be directly connected to the global star-forming sequence. This suggests that the global main sequence may be a consequence of a more fundamental relation on small scales. On the other hand, our result suggests that about 20% of quiescent galaxies in our sample still have star formation activities in the outer region with lower SSFR than typical star-forming galaxies. Meanwhile, we also find a tight correlation between Sigma_H_alpha and Sigma_star for LI(N)ER regions, named the resolved "LI(N)ER" sequence, in quiescent galaxies, which is consistent with the scenario that LI(N)ER emissions are primarily powered by the hot, evolved stars as suggested in the literature.