High-redshift radio galaxies are among the most massive galaxies in the Universe and sites of extreme active galactic nucleus feedback processes, powering energetic radio jets. They are typically embedded in giant Lyα halos that are known to extend over 100, ^ into the circumgalactic medium. We targeted the Lyα halos around four high-redshift radio galaxies in a redshift range of 3. 1 < z < 4. 5 using high-resolution spectroscopy from the Ultraviolet Echelle Spectograph (UVES) at the VLT, focusing on absorption features in the Lyα emission that trace neutral hydrogen (H, ) systems. We compared the UVES data to observations obtained with the Multi Unit Spectroscopic Explorer (MUSE) of the same targets and found that the higher spectral resolution of UVES (Δ v ≈ 12, i km s -1) allowed us to identify absorbers more completely and revealed the splitting of deep absorbers into multiple components. We identified between 6 and 14 absorbers for each target in our sample with column densities of N_ H, i = 10^ 12 -10^ 17, ^ cm -2. About 70, % of the absorbers can be spatially resolved along the radio jet axis, showing minimal variation in column densities over extents of more than 30 kpc. Our results indicate that a fraction of the absorbers may be physically associated with the host systems. Complementary JWST/NIRSpec observations of two of the targets, 4C+03. 24 and TN, J0205, reveal potential outflows in the ionized interstellar medium. We discuss a kinematic link between the O iii -emitting gas and the cool halo gas as traced by Lyα, suggesting a common outflow origin.
Ritter et al. (Mon,) studied this question.
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