Clumpiness of galaxies revealed in the near-infrared with COSMOS-Web
Clumpiness of galaxies revealed in the near-infrared with COSMOS-Web
Clumps in the rest-frame UV emission of galaxies have been observed for decades. Since the launch of the James Webb Space Telescope (JWST), a large population is detected in the rest-frame near-infrared (NIR), raising questions about their formation mechanism. We investigate the presence and properties of NIR over-densities (hereafter substructures) in star-forming and quiescent galaxies at 1 < z < 4 to understand their link to the evolution of their host galaxy. We identify substructures in JWST/NIRCam F277W and F444W residual images at a rest-frame wavelength of 1 um. The fraction of galaxies with substructures with M* > 10^9 Msun has been steadily decreasing with cosmic time from 40% at z = 4 to 10% at z = 1. Clumps, the main small substructures in the rest-frame NIR, are the most common type and are much fainter (2% of the flux) than similar UV clumps in the literature. Nearly all galaxies at the high-mass end of the main sequence (MS), starburst, and green valley regions have substructures. However, we do not find substructures in low-mass galaxies in the green valley and red sequence. Although massive galaxies on the MS and in the green valley have a 40% probability of hosting multiple clumps, the majority of clumpy galaxies host only a single clump. The fraction of clumpy galaxies in the rest-frame NIR is determined by the stellar mass and SFR of the host galaxies. Its evolution with redshift is due to galaxies moving towards lower SFRs at z < 2 and the build-up of low-mass galaxies in the green valley and red sequence. Based on their spatial distribution in edge-on galaxies, we infer that most of substructures are produced in-situ via disk fragmentation. Galaxy mergers may still play an important role at high stellar masses, especially at low SFR.
Wilfried Mercier、Boris Sindhu Kalita、Marko Shuntov、Rafael C. Arango-Toro、Olivier Ilbert、Laurence Tresse、Yohan Dubois、Clotilde Laigle、Hossein Hatamnia、Nicolas McMahon、Andreas Faisst、Isa Cox、Maxime Trebitsch、Leo Michel-Dansac、Si-Yue Yu、Michaela Hirschmann、Marc Huertas-Company、Arianna Long、Anton Koekemoer、Grégoire Aufort、Joseph Lewis、Ghassem Gozaliasl、R. Michael Rich、Jason Rhodes、Henry Joy McCracken、Caitlin Casey、Jeyhan Kartaltepe、Brant Robertson、Maximilien Franco、Daizhong Liu、Hollis Akins、Natalie Allen、Sune Toft
天文学
Wilfried Mercier,Boris Sindhu Kalita,Marko Shuntov,Rafael C. Arango-Toro,Olivier Ilbert,Laurence Tresse,Yohan Dubois,Clotilde Laigle,Hossein Hatamnia,Nicolas McMahon,Andreas Faisst,Isa Cox,Maxime Trebitsch,Leo Michel-Dansac,Si-Yue Yu,Michaela Hirschmann,Marc Huertas-Company,Arianna Long,Anton Koekemoer,Grégoire Aufort,Joseph Lewis,Ghassem Gozaliasl,R. Michael Rich,Jason Rhodes,Henry Joy McCracken,Caitlin Casey,Jeyhan Kartaltepe,Brant Robertson,Maximilien Franco,Daizhong Liu,Hollis Akins,Natalie Allen,Sune Toft.Clumpiness of galaxies revealed in the near-infrared with COSMOS-Web[EB/OL].(2025-06-16)[2025-07-16].https://arxiv.org/abs/2506.13881.点此复制
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