http://arxiv.org/abs/2107.07100
Giant radio galaxies provide important clues into the life cycles and triggering mechanisms of radio jets. With large-scale jets spanning 1.8 Mpc, ESO 422-G028 ($z = 0.038$) is a giant radio galaxy that also exhibits signs of restarted jet activity in the form of pc-scale jets. We present a study of the spatially-resolved stellar and gas properties of ESO 422-G028 using optical integral field spectroscopy from the WiFeS spectrograph. In addition to the majority $\sim 13\,\rm Gyr$ old stellar population, ESO 422-G028 exhibits a much younger ($\lesssim 10\,\rm Myr$ old) component with an estimated mass of $ 10^{7.6}\,\rm M_\odot$ which is predominantly located in the North-West region of the galaxy. Unusually, the ionised gas kinematics reveal two distinct disks traced by narrow ($\sigma_{\rm H\alpha} < 100 \,\rm km\,s^{-1}$) and broad ($\sigma_{\rm H\alpha} > 150 \,\rm km\,s^{-1}$) H$\alpha$ emission respectively. Both ionised gas disks are misaligned with the axis of stellar rotation, suggesting an external origin. This is consistent with the prominent interstellar Na D absorption, which traces a $1 – 3 \,\rm M_\odot \, yr^{-1}$ inflow of neutral gas from the North. We posit that an inflow of gas – either from an accretion event or a gas-rich merger – has triggered both the starburst and the restarted jet activity, and that ESO 422-G028 is potentially on the brink of an epoch of powerful AGN activity.
H. Zovaro, C. Riseley, P. Taylor, et. al.
Fri, 16 Jul 21
23/61
Comments: 21 pages, 19 figures; submitted to the Monthly Notices of the Royal Astronomical Society
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