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arXiv · 2509.20720

Formation of Substructure in Luminous Submillimeter Galaxies (FOSSILS): Initial sample and the discovery of a dusty spiral at cosmic noon

Ryota Ikeda·Daisuke Iono·Ken-ichi Tadaki·Andrea Silva·the FOSSILS Team
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Abstract

High-resolution far-infrared (FIR) observation of submillimeter galaxies (SMGs) is an effective approach to study the formation of substructures in the early epoch of massive galaxies. We present the 870$\mu$m continuum images resolved down to sub-kpc scales for 12 SMGs taken by Atacama Large Millimeter/Submillimeter Array (ALMA) as an initial sample of the FOSSILS Survey. We discovered a wide variety of morphological properties, including a two-arm spiral galaxy at $z=2.5$ possibly induced by a tidal interaction with a minor companion. Nonetheless, about half of the sample exhibit a compact and circular morphology, which is reminiscent of optical morphology of compact quiescent galaxies. Future studies with larger sample and combination of the rest-frame optical images taken by James Webb Space Telescope will shed light on the various evolutionary track of SMGs.

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Ryota Ikeda, Daisuke Iono, Ken-ichi Tadaki, Andrea Silva, the FOSSILS Team. 2025-09-25. Formation of Substructure in Luminous Submillimeter Galaxies (FOSSILS): Initial sample and the discovery of a dusty spiral at cosmic noon. https://arxiv.org/abs/2509.20720

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