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Ionization and feedback in Lyα haloes around two radio galaxies at z ~ 2.5

S. G. Morais, A. Humphrey, M. Villar-MartÝn, P. Lagos, M. M. Moyano, R. Overzier, S. Di Serego Alighieri, J. Vernet, C. A. C Fernandes

Abstract
We present new spectroscopic observations of two high-redshift radio galaxies, TXS 0211−122 (z = 2.34) and TXS 0828+193 (z = 2.57), known to be associated with large Lyα haloes. The observations were taken with the slits placed perpendicularly to the radio axis. With access to pre-existing Keck II observations taken with the slit placed along the radio axis, we are able to compare the properties of the gas in different regions of the galaxies. In both objects, we detect spatially extended Lyα emission perpendicularly to the radio axis. In TXS 0211−122, the flux and velocity profiles of Lyα are strongly affected by H i absorption/scattering. In line with previous studies, we find evidence for outflowing gas along the radio axis which may be the result of jet–gas interactions. In the slit oriented perpendicularly to the radio axis we find less perturbed gas kinematics, suggesting outflows of ionized gas in this object are focused along the radio jet axis. Additionally, we find evidence for a giant, UV-emitting arc or shell-like structure surrounding the radio galaxy Lyα halo, possibly resulting from feedback activity. In TXS 0828+193, a large Lyα halo (∼56 kpc) is detected perpendicularly to the radio axis. Along both slit position angles we find evidence for outflowing gas, which we argue is part of an approximately spherical, expanding shell or bubble of gas powered by feedback activity in the central regions of the galaxy. Our results suggest a diversity in the spatial distribution of ionized outflows in powerful radio galaxies at z ∼ 2.5.

Keywords
galaxies: active – galaxies: high-redshift – galaxies: individual: TXS 0211-122 – galaxies: individual: TXS 0828+193.

Monthly Notices of the Royal Astronomical Society
Volume 465, Issue 3, Page 2698
2017 March

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Instituto de Astrof├şsica e Ci├¬ncias do Espa├žo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa Funda├ž├úo para a Ci├¬ncia e a Tecnologia
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