Multiple paths to quiescence: a spectroscopic view from the LEGA-C survey

Po-Feng Wu (MPIA)
Friday, January 25, 2019 - 12:15pm to 1:00pm

The stars in galaxies record the fossil record of galaxy formation. I present the Large Early Galaxy Astrophysics Census (LEGA-C) survey, an ESO VLT/VIMOS survey that obtains ~3000 Ks-band-selected spectra for studying the stellar continua of galaxies at z~1. The high-quality spectra allow us to derive stellar ages and trace their formation histories for individual galaxies. From the accurate ages, we find a complex correlation between the sizes and ages of quiescent galaxies. While younger galaxies are on average larger, a small fraction of galaxies, whose star-formation rates are declining rapidly (post-starburst galaxies), is compact objects. This complex age-size correlation suggests that there are multiple ways to quiescence. Slow processes produce large quiescent galaxies, while fast processes are companioned with structural change, producing small quiescent galaxies. Lastly, I will discuss the formation of post-starburst galaxies, the proxy for understanding the fast quenching.

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