Oral Presentation

Resolved dust emission of typical star-forming galaxies at z=4-6

Author(s): Ikki Mitsuhashi (the University of Tokyo), Ken-ichi Tadaki, Ryota Ikeda (NAOJ), and the CRISTAL team

Presenter: Ikki Mitsuhashi (University of Tokyo)

Submillimeter morphologies of high redshift galaxies are essential for understanding galaxy evolution as a tracer of obscured star formation. In the ALMA cycle-8 large program, CRISTAL, we have individually detected dust continuum emission from 15 typical star-forming galaxies at z=4-6 with an order of magnitude lower far-infrared luminosity than massive dusty star-forming galaxies (DSFGs). The fraction of dust-obscured star formation is ~50%, and it tends to be increased by interactions. Thanks to high-resolution and deep observations, we could measure the dust continuum size of these galaxies. The effective radii of the dust emission are on average ~1.5kpc and are almost comparable with the rest-frame UV sizes of these galaxies. The infrared surface densities of these galaxies are one order fainter than DSFGs, which show a compact starburst in the center. Based on the comparable contribution of dust-obscured and dust-unobscured star formation and comparable spatial extent, it is suggested that typical star-forming galaxies are forming their disks through their widespread star formation.