Speaker
Description
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 first present new ALMA continuum observations of a dusty galaxy at $z=7.31$ in six unique bands (including Band 9) which meticulously constrain its dust SED and demonstrate it to host a massive dust reservoir. Producing such a large dust mass so shortly after the Big Bang likely requires efficient grain growth in a dense ISM, on top of efficient dust production from supernovae. This suggests the galaxy to be a rather evolved system already by $z > 7$, which is supported by recent high-resolution ($\sim0.2''$) [CII] observations demonstrating it to be a rotating disk — the most distant cold disk known to date. I will present matched-resolution Band 8 dust continuum and [OIII] observations of this spectacular galaxy, and discuss its multi-band kinematics, star formation and ISM properties at high spatial resolution.
