SDSS IV MaNGA: Dependence of Global and Spatially Resolved SFR–M_∗ Relations on Galaxy Properties

Abstract

The galaxy integrated Hα star formation rate-stellar mass relation, or SFR(global)-M * (global) relation, is crucial for understanding star formation history and evolution of galaxies. However, many studies have dealt with SFR using unresolved measurements, which makes it difficult to separate out the contamination from other ionizing sources, such as active galactic nuclei and evolved stars. Using the integral field spectroscopic observations from SDSS-IV MaNGA, we spatially disentangle the contribution from different Hα powering sources for ∼1000 galaxies. We find that, when including regions dominated by all ionizing sources in galaxies, the spatially resolved relation between Hα surface density (Σ Hα (all)) and stellar mass surface density (Σ * (all)) progressively turns over at the high Σ * (all) end for increasing M * (global) and/or bulge dominance (bulge-to-total light ratio, B/T). This in turn leads to the flattening of the integrated Hα(global)-M * (global) relation in the literature. By contrast, there is no noticeable flattening in both integrated Hα(H II)-M * (H II) and spatially resolved Σ Hα (H II)-Σ * (H II) relations when only regions where star formation dominates the ionization are considered. In other words, the flattening can be attributed to the increasing regions powered by non-star-formation sources, which generally have lower ionizing ability than star formation. An analysis of the fractional contribution of non-star-formation sources to total Hα luminosity of a galaxy suggests a decreasing role of star formation as an ionizing source toward high-mass, high-B/T galaxies and bulge regions. This result indicates that the appearance of the galaxy integrated SFR-M * relation critically depends on their global properties (M * (global) and B/T) and relative abundances of various ionizing sources within the galaxies.

Resolved galaxy scaling relations in the eagle simulation: star formation, metallicity, and stellar mass on kpc scales

“…Cano-Díaz et al (2016) find no clear M dependence in the Σ − Σ SFR relation for CALIFA galaxies. Pan et al (2018) find some trends between M and the Σ − Σ Hα relation, exhibiting a similar flattening in the relation at higher M , but attribute this to the influence of ionisation mechanisms other than star formation. However, other studies (e.g.…”

From Global to Spatially Resolved in Low-Redshift Galaxies

“…cloud of points well below the SFMS). The agreement between global and local relations was already explored in detail by Pan et al (2018) and Cano-Díaz et al (2019), being in general good.…”

SDSS-IV MaNGA: effects of morphology in the global and local star formation main sequences

“…More recently, some studies have found that the SFMS relation has a local (spatially-resolved) counterpart in the diagram that relates the SFR surface density (Σ S FR ) with the stellar mass surface density (Σ * ) (Sánchez et al 2013;Wuyts et al 2013;Magdis et al 2016;Cano-Díaz et al 2016;Maragkoudakis et al 2017;Abdurro'uf & Akiyama 2017;Hsieh et al 2017;Pan et al 2018;Ellison et al 2018;Medling et al 2018;Erroz-Ferrer et al 2019). This spatially resolved diagram aims to look for the star formation process at a local level within the galaxies (at ∼kpc scales).…”