Mapping the “invisible” circumgalactic medium around a z ∼ 4.5 radio galaxy with MUSE

¹ Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12-14, 69120 Heidelberg, Germany
e-mail: wuji.wang@uni-heidelberg.de; wuji.wang_astro@outlook.com
² European Southern Observatory, Karl-Schwarzchild-Str. 2, 85748 Garching, Germany
³ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
⁴ Centro de Astrobiología, CSIC-INTA, Ctra. de Torrejón a Ajalvir, km 4, 28850 Torrejón de Ardoz, Madrid, Spain
⁵ Univ. Lyon, Univ. Lyon1, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, 69230 Saint-Genis-Laval, France
⁶ Inter-University Institute for Data Intensive Astronomy, Department of Astronomy, University of Cape Town, Rondebosch 7701, South Africa
⁷ Physics Department, University of Johannesburg, 5 Kingsway Ave, Rossmore, Johannesburg 2092, South Africa

Received: 16 June 2021
Accepted: 19 July 2021

Abstract

In this paper we present Multi Unit Spectroscopic Explorer integral field unit spectroscopic observations of the ∼70 × 30 kpc² Lyα halo around the radio galaxy 4C04.11 at z = 4.5077. High-redshift radio galaxies are hosted by some of the most massive galaxies known at any redshift and are unique markers of concomitant powerful active galactic nucleus (AGN) activity and star formation episodes. We map the emission and kinematics of the Lyα across the halo as well as the kinematics and column densities of eight H I absorbing systems at −3500 < Δv < 0 km s⁻¹. We find that the strong absorber at Δv ∼ 0 km s⁻¹ has a high areal coverage (30 × 30 kpc²), being detected across a large extent of the Lyα halo, a significant column density gradient along the southwest to northeast direction, and a velocity gradient along the radio jet axis. We propose that the absorbing structure, which is also seen in C IV and N V absorption, represents an outflowing metal-enriched shell driven by a previous AGN or star formation episode within the galaxy and is now caught up by the radio jet, leading to jet-gas interactions. These observations provide evidence that feedback from AGN in some of the most massive galaxies in the early Universe may play an important role in redistributing material and metals in their environments.