The Two Component Circumgalactic Medium Emission around z~2 Radio-loud Quasars

TL;DR

This study investigates the emission properties of the circumgalactic medium around z~2 radio-loud quasars, revealing a two-component structure influenced by quasar photoionization and environmental factors.

Contribution

It provides new observational evidence for a two-component model of the CGM around high-redshift quasars, combining Lyα, He II, and C IV emission data.

Findings

Inner CGM ( < 30 kpc) is brighter and directly influenced by the host galaxy.

Outer CGM (> 30 kpc) shows signs of turbulence and environmental effects.

He II and C IV emissions are likely powered by quasar photoionization along radio jets.

Abstract

We present Ly$\alpha$, He II and C IV observations of 7 redshift ~ 2 radio-loud quasars observed using the Keck Cosmic Web Imager (KCWI) and compare it to observed radio jet emission using archival VLA and ALMA radio observations. We detect 80-120 kpc diameter Ly$\alpha$ and 10-40 kpc He II and C IV emission around the targets. We find the Ly$\alpha$ emission to be brighter in 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 area on sky, 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 CGM where the inner CGM (< 30 kpc) is directly influenced by the host galaxies, whereas the gas motion in the outer CGM (> 30 kpc) is influenced by gas turbulence and the larger environment around the host galaxies.