Seminari
Monday 14/02/2022 @ 14:30, On-line - meet.google.com/sue-bwvk-axf
Kristina Nyland (U.S. Naval Research Laboratory), "Young Quasar Jets in the Era of Multi-epoch Radio Surveys"
Systematic studies of quasars with young jets are essential for understanding the triggering, formation, and life cycles of jets and their connection to galaxy evolution. However, the faint (mJy-level) and high-redshift (z>1) populations of young radio jets have yet to be fully explored due to the limitations (e.g. sensitivity and/or resolution) of historical radio surveys. The comparison of sensitive widefield radio survey data taken over multiple epochs spanning years or longer provides a new opportunity to identify this unexplored population of young quasar jets on the basis of variability. Using this strategy, I have compiled a sample of powerful quasars that appear to have recently “switched-on” based on a comparison between data from the Very Large Array Sky Survey (VLASS) and the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey taken 1-2 decades apart. Follow-up VLA observations have revealed compact (sub-kpc) morphologies and peaked radio spectral shapes consistent with young/compact jets. In this talk, I will present new multi-epoch radio spectra and discuss possible implications for origin of the variable radio emission. I will also discuss prospects for advancements in understanding the life cycles of quasar jets with new and future surveys of the dynamic radio sky.