The Two-component Circumgalactic Medium Emission around z ∼ 2 Radio-loud Quasars
May 2026 • 2026ApJ..1002..170S
Abstract • We present Lyα, He II, and C IV observations of seven z ∼ 2 radio-loud quasars observed using the Keck Cosmic Web Imager and compare it to observed radio jet emission using archival Very Large Array and Atacama Large Millimeter/submillimeter Array radio observations. We detect 80─120 kpc diameter Lyα and 10─40 kpc He II and C IV emission around the targets. We find the Lyα emission to be brighter within the inner 30 kpc by factors of 2─10 compared to other literature samples. We reproduce the trend for increased total luminosity for a larger on-sky area, but find our targets tend to be brighter for a given area when compared to literature observations, even when adjusting for the observational sensitivity. We infer that the He II and C IV is likely powered by quasar photoionization, with the ionizing radiation likely escaping along the radio jet axis, which is aligned with the He II and C IV emission. The observations agree with a two-component model of the circumgalactic medium (CGM), where the inner CGM (<30 kpc) is directly influenced by the host galaxies, whereas gas motions in the outer CGM (>30 kpc) are governed by turbulence and the larger-scale environment.
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