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Early results on the formation of galaxy disks from deep JWST spectral maps of galaxies at intermediate redshifts

Apr 21, 2026   3:45 - 4:45 pm  
Astronomy Building
Astronomy
Sponsor
Department of Astronomy
Speaker
Dr. Susan Kassin
Contact
Daniel Franco
E-Mail
danielf9@illinois.edu
Phone
217-300-6769
Originating Calendar
Astronomy Colloquium Speaker Calendar

Galaxies at redshift of z = 1− 6 are the building blocks that evolve into recognizable Hubble Sequence galaxies after z ∼ 1. However, little is known about these early systems beyond z ∼ 2.5–3. We know nothing of their dynamical state, whether they are even remotely angular momentum-supported disks, turbulent mergers, bits and pieces of minor mergers just assembling in a dark halo potential, or some mixture of these states. Little is known about how they interact with the circumgalactic medium in which they are imbedded.  Measurements of their outflows generally are not spatially resolved and are often stacked, even for the brightest galaxies.  We have begun to measure these phenomena with the NIRSpec spectrograph on JWST for a sample of 56 galaxies in the Ultra Deep Field as part of the “GARDEN” survey.   GARDEN consists of exceptionally deep and spatially resolved rest-frame optical spectroscopy of nebular emission lines and stellar/outflow absorption lines.  These data are obtained with a new observing mode we invent for JWST called “slitlet stepping.”  This talk will present early results on the gas kinematics of galaxies, their interface with the CGM, the surprising presence of thick and thin gaseous disks at z~2, and possibly the first map of a neutral gas outflow in a galaxy at z~2.

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