Galaxy mass-size segregation in the cosmic web from the CAVITY parent sample

Context. The mass-size relation is a fundamental galaxy scaling relation that is intrinsically linked to galaxy formation and evolution. The physical processes involved in galaxy growth leave their particular imprint on the relation between the stellar or total mass and galaxy size. Aims. We aim to explore the effect of the large-scale environment on the stellar mass-size relation using samples and a selection of added-value products from the Calar Alto Void Integral-field Treasury surveY (CAVITY) collaboration. Methods. We analysed the Petrosian R50 and R90 radii from SDSS DR16 images of a sample of ≈14 000 galaxies inhabiting cosmic voids, filaments and walls, and clusters, with a stellar mass range between 10 8.5 − 10 11 M ⊙ . We investigated the mass-size relation with respect to the galaxy morphology, as well as with the star formation history (SFH), parametrised across a range of different timescales ( T 50 , T 70 , and T 90 ). Results. We find that, on average, early-type galaxies in voids are approximately 10−20% smaller than their counterparts in denser environments, such as filaments, walls, and clusters, regardless of when they assembled their mass. Additionally, evidence suggests that the mass-size relation for the more massive void galaxies within the early-type sample exhibits a shallower slope, compared to galaxies in denser large-scale environments. In contrast, early-type galaxies in filaments, walls, and clusters exhibit a more consistent mass-size distribution. For stellar masses of log( M ⋆ /M ⊙ ) = 9 − 10.5, late-type cluster galaxies are smaller and more concentrated than those in lower density environments, such as filaments, walls, and voids; whereas void and filament+wall galaxies exhibit similar size and concentration values. However, for galaxies with masses above 10 10.5 M ⊙ , the sizes of void galaxies become comparable to those in clusters. The trend of smaller low-mass cluster galaxies is primarily driven by galaxies with T 50 greater than 7 Gyr. Conclusions. We conclude that the large-scale environment influences the mass-size relation of galaxies. Assuming that early-type galaxies undergo two growth phases, we find that they primarily grow their mass during the first phase of formation. In voids, the subsequent size growth from minor mergers is less pronounced. This is likely due to slower evolution and reduced minor merger activity or the fact that the void environment inherently has fewer accretion events, or even a combination of these effects. The change in slope for high-mass void galaxies suggests a lower rate of minor accretion. This trend is also evident in late-type void galaxies with masses above ≈10 10.5 M ⊙ , where minor mergers contribute to their size growth. In contrast, late-type quenched cluster galaxies are smaller in size due to interactions within the cluster environment, with early infallers being more strongly affected by these environmental interactions.