EXCELlent Work, Detectives! Solving the Murder of Star Formation in Galaxies with JWST

by Margaret Verrico | Jun 12, 2026

Title: The JWST EXCELS survey: Insights into the nature of quenching at cosmic noon Authors: Maya Skarbinski, Kate Rowlands, Katherine Alatalo, Vivienne Wild, Adam C. Carnall, Omar Almaini, David Maltby, Thomas de Lisle, Timothy Heckman, Ryan Begley, Fergus Cullen, James S. Dunlop, Guillaume Hewitt, Ho-Hin Leung, Derek McLeod, Ross McLure, Justin Atsushi Otter, Pallavi Patil, Andreea Petric, Alice E. Shapley, Struan Stevenson, Elizabeth Taylor First Author’s Institution: William H. Miller III Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland, USA Status: Published in the Astrophysical Joural [open access] How to Quench a Galaxy Look at an image of the sky taken with a sufficiently sensitive telescope, and you’ll quickly notice that galaxies tend to cluster into two main types: blue spiral galaxies, which have flat disk shapes with a central bulge, and red elliptical galaxies, which look like spherical or elliptical balls of red stars. Blue spiral galaxies can form 10s–100s of stars every year, while elliptical galaxies have completely stopped forming stars, meaning that some process has to transform star-forming spirals into non-star-forming, or “quiescent,” elliptical galaxies. To form the current population of massive elliptical galaxies, this process had to be common about 8–10 billion years ago at “Cosmic Noon,” the period when star formation in the Universe peaked. The processes that “quench” star formation in massive galaxies are still being studied, and one of the best ways to do it is to find galaxies that recently quenched and look for clues about the processes that quenched them.  Post-starburst galaxies are galaxies that have rapidly quenched after a short burst of star formation. Because these galaxies…