GASP – XX. From the loose spatially resolved to the tight global SFR–mass relation in local spiral galaxies. Issue 2 (4th July 2019)

• Record Type: Journal Article
• Authors: Vulcani, Benedetta; Poggianti, Bianca M; Moretti, Alessia; Franchetto, Andrea; Gullieuszik, Marco; Fritz, Jacopo; Bettoni, Daniela; Tonnesen, Stephanie; Radovich, Mario; Jaffé, Yara L; McGee, Sean; Bellhouse, Callum; Fasano, Giovanni
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 488:Issue 2(2019)
• Page Start: 1597
• Page End: 1617
• Publication Date: 2019-07-04
• Subjects: galaxies: evolution -- galaxies: spiral -- galaxies: star formation; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz1829
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: Exploiting the sample of 30 local star-forming, undisturbed late-type galaxies in different environments drawn from the GAs Stripping Phenomena in galaxies with MUSE (GASP), we investigate the spatially resolved star formation rate–mass ($\rm \Sigma _{SFR}$ –$\rm \Sigma _\ast$ ) relation. Our analysis includes also the galaxy outskirts (up to >4 effective radii, r e ), a regime poorly explored by other Integral Field Spectrograph surveys. Our observational strategy allows us to detect H α out to more than 2.7 r e for 75 per cent of the sample. Considering all galaxies together, the correlation between the $\rm \Sigma _{SFR}$ and $\rm \Sigma _\ast$ is quite broad, with a scatter of 0.3 dex. It gets steeper and shifts to higher $\rm \Sigma _\ast$ values when external spaxels are excluded and moving from less to more massive galaxies. The broadness of the overall relation suggests galaxy-by-galaxy variations. Indeed, each object is characterized by a distinct $\rm \Sigma _{SFR}$ –$\rm \Sigma _\ast$ relation and in some cases the correlation is very loose. The scatter of the relation mainly arises from the existence of bright off-centre star-forming knots whose $\rm \Sigma _{SFR}$ –$\rm \Sigma _\ast$ relation is systematically broader than that of the diffuse component. The $\rm \Sigma _{SFR}$ –$\rm \Sigma _{tot \, gas}$ (total gas surface density) relation is as broad as the $\rm \Sigma _{SFR}$ –$\rm \Sigma _\ast$ relation, indicating that the surface gas density is not a primary driver of the relation. Even though a large galaxy-by-galaxy variation exists, mean $\rm \Sigma _{SFR}$ and $\rm \Sigma _\ast$ values vary of at most 0.7 dex across galaxies. We investigate the relationship between the local and global SFR– M * relation, finding that the latter is driven by the existence of the size–mass relation.