Oral Presentation

The Resolved Dust and Interstellar Medium of a z=7.31 Rotating Disk

Author(s): Hiddo Algera (Hiroshima University / NAOJ)

Presenter: Hiddo Algera (Hiroshima University / NAOJ)

Over the last decade, ALMA has revolutionized our understanding of the interstellar medium (ISM) conditions of distant galaxies. For one, ALMA has now detected (sub-)millimeter continuum emission from dozens of galaxies at z > 6.5, establishing the importance of dust-obscured star formation already within the first 800 Myr after the Big Bang. Moreover, through various bright emission line diagnostics such as [CII]158 and [OIII]88, ALMA can be used to directly study the physical conditions and kinematics of the ISM within the earliest galaxies.

In this talk, I will use observations from half a dozen different ALMA campaigns to study the dust and interstellar medium properties of REBELS-25: a spectacular, but otherwise normal, massive dusty galaxy at z=7.31. First, I will use six-band ALMA continuum observations to accurately constrain its dust SED, and demonstrate REBELS-25 to host a massive dust reservoir. Following this, I will move onto resolved scales: using new, high-resolution (~0.2") [CII] observations, I will show REBELS-25 to be a rotating disk galaxy -- the most distant cold disk known to date. I will then discuss matched-resolution Band 8 dust continuum and [OIII] observations, which provide a resolved dust temperature and [OIII]/[CII] map of this spectacular galaxy. Finally, I will compare this wealth of ALMA data with new JWST/NIRSpec IFU observations of REBELS-25, and shed light on how dust obscuration can bias our interpretation of early massive galaxies.