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arXiv · 1907.00976

GASP. XX. From the loose spatially-resolved to the tight global SFR-Mass relation in local spiral galaxies

Benedetta Vulcani·Bianca M. Poggianti·Alessia Moretti·Andrea Franchetto·Marco Gullieuszik·Jacopo Fritz·Daniela Bettoni·Stephanie Tonnesen·Mario Radovich·Yara L. Jaffe·Sean McGee·Callum Bellhouse·Giovanni Fasano
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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 ({\Sigma}SFR-{\Sigma}_star) relation. Our analysis includes also the galaxy outskirts (up to >4 effective radii, re), a regime poorly explored by other Integral Field Spectrograph surveys. Our observational strategy allows us to detect H{\alpha} out to more than 2.7re for 75% of the sample. Considering all galaxies together, the correlation between the {\Sigma}SFR and {\Sigma}_star is quite broad, with a scatter of 0.3 dex. It gets steeper and shifts to higher {\Sigma}_star 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 {\Sigma}SFR-{\Sigma}_star relation and in some cases the correlation is very loose. The scatter of the relation mainly arises from the existence of bright off-center star-forming knots whose {\Sigma}SFR-{\Sigma}_star relation is systematically broader than that of the diffuse component. The {\Sigma}SFR-{\Sigma}tot gas (total gas surface density) relation is as broad as the {\Sigma}SFR-{\Sigma}_star 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 {\Sigma}SFR and {\Sigma}_star values vary of at most 0.7 dex across galaxies. We investigate the relationship between the local and global SFR-M_star relation, finding that the latter is driven by the existence of the size-mass relation.

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Benedetta Vulcani, Bianca M. Poggianti, Alessia Moretti, Andrea Franchetto, Marco Gullieuszik, Jacopo Fritz, Daniela Bettoni, Stephanie Tonnesen, Mario Radovich, Yara L. Jaffe, Sean McGee, Callum Bellhouse, Giovanni Fasano. 2019-07-01. GASP. XX. From the loose spatially-resolved to the tight global SFR-Mass relation in local spiral galaxies. https://doi.org/10.1093/mnras/stz1829

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