Speaker
Description
Recent observations with the James Webb Space Telescope (JWST) are revealing an increasing number of quiescent galaxies that had already stopped forming stars when the Universe was only a few billion years old. Given the limited time available for secular evolution at these early epochs, the existence of such quenched systems suggests that their star formation was abruptly shut down. Identifying the physical mechanisms responsible for this early and rapid quenching remains a key challenge in galaxy evolution. Post-starburst galaxies (PSBs), which have shut down their star formation both recently and rapidly, provide a unique opportunity to study these quenching mechanisms.
In this work, we investigate spatially resolved stellar age gradients in a sample of nine PSBs at 1 < z < 1.5 using multi-band JWST and HST imaging. Six PSBs show younger central stellar populations, while three exhibit flat age gradients. Overall, our analysis reveals predominantly younger stellar populations in the central regions of PSBs, consistent with recent centrally concentrated star formation superimposed on an older, more extended stellar component. This results in flat or mildly positive radial age gradients. The observed central starbursts may be driven by dissipative processes such as secular disk instabilities or gas-rich mergers, followed by rapid quenching via disk stabilization or feedback from active galactic nuclei (AGN) and massive stars. Our results support a fast quenching scenario, indicating that multiple mechanisms likely act together to drive the rapid transition from star-forming to quiescent phases in PSBs at this redshift.
Keywords: Post-starburst galaxies (PSBs), Stellar age gradients, Rapid quenching
| Participate the oral/poster presentation award competition | Yes |
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