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Tracing quasar origins of radio emission through CIV parameter space

Presentation #101.26 in the session AGN & Quasars — iPoster Session.

Published onJun 29, 2022
Tracing quasar origins of radio emission through CIV parameter space

Using a sample of 438 1.6<z<2.2 quasars from the SDSS, we explore the use of broad CIV emission to constrain the origins of radio emission in radio-quiet quasars. Accurate placement of the quasar sample in CIV equivalent width (EW)-blueshift space enables the creation of a new emission-line metric, the “CIV distance,” which isolates quasars with excess radio emission at either extreme of the CIV parameter space. We find that quasars with small CIV distance (high EW, small blueshift) have high radio detection fractions that are likely the result of small-scale jets or radio-active coronae, while quasars with high CIV distance (low EW, high blueshift) show radio excess that is due either to star formation or shocks from strong quasar winds; quasars with intermediate CIV distance (low EW, low blueshift) show no such excess. These results suggest more than one underlying process, although more dedicated pointed observations are needed to fully characterize radio emission in quasars. To achieve deeper high-resolution imaging, we have obtained sensitive A-configuration observations in the currently ongoing VLA cycle to test for systemic morphological differences at opposite ends of the CIV space. These new observations will provide a test for the growing picture that radio emission from radio-quiet quasars may have several physical origins, from jets, to shocks, to star formation.

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