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arXiv · 2507.16212

Early-type Galaxies on the Star Formation Main Sequence: Internal Star Formation Geometry Revealed with MaNGA and Their Environmental Origin

Shuhei Koyama·Yusei Koyama·Takuji Yamashita·Masahiro Konishi·Kosuke Kushibiki·Kentaro Motohara
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Abstract

Star-forming galaxies on the main sequence (MS) are often regarded as a uniform population characterized by similar global star formation properties. However, there exists a diversity in galaxy morphologies at fixed stellar mass and SFR. In this study, using spatially-resolved properties from the MaNGA final data release, we classify MS galaxies into late-type (MS-late) and early-type (MS-early). In addition, we further divide the MS-early galaxies into two distinct subgroups based on their internal star formation and stellar mass distributions within the galaxies. The first group -- ``MS-early\_SF'' -- shows centrally concentrated star formation without prominent stellar bulges and resides preferentially in dense environments, suggesting environmentally-driven evolution. The second group -- ``MS-early\_stellar'' -- exhibits significant stellar bulges with suppressed central star formation, maintains disk-like star formation patterns, and inhabits environments similar to those of late-type galaxies, indicating evolution through internal secular processes. Our findings demonstrate that spatially-resolved observations play critical roles in revealing the diverse evolutionary pathways hidden within galaxies that share similar global properties.

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Shuhei Koyama, Yusei Koyama, Takuji Yamashita, Masahiro Konishi, Kosuke Kushibiki, Kentaro Motohara. 2025-07-22. Early-type Galaxies on the Star Formation Main Sequence: Internal Star Formation Geometry Revealed with MaNGA and Their Environmental Origin. https://arxiv.org/abs/2507.16212

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