Powerful ionized gas outflows in the interacting radio galaxy 4C+29.30

Abstract

We investigate the ionized gas excitation and kinematics in the inner $4.3\, \times \, 6.2$ kpc² of the merger radio galaxy 4C+29.30. Using optical integral field spectroscopy with the Gemini North Telescope, we present flux distributions, line-ratio maps, peak velocities and velocity dispersion maps as well as channel maps with a spatial resolution of $\approx\! 955\,$ pc. We observe high blueshifts of up to $\sim\! -650\,$$\rm km\, s^{-1}$ in a region ~1 arcsec south of the nucleus (the southern knot - SK), which also presents high velocity dispersions ($\sim\! 250\,$$\rm km\, s^{-1}$), which we attribute to an outflow. A possible redshifted counterpart is observed north from the nucleus (the northern knot - NK). We propose that these regions correspond to a bipolar outflow possibly due to the interaction of the radio jet with the ambient gas. We estimate a total ionized gas mass outflow rate of $\dot{M}_{\mathrm{ out}} = 25.4 ^{+11.5 }_{ -7.5}\,$ M_⊙ yr^-1with a kinetic power of $\dot{E} = 8.1 ^{+10.7 }_{ -4.0} \times 10^{42}\,$ erg s^-1, which represents $5.8 ^{+7.6 }_{ -2.9} {{\ \rm per\ cent}}$ of the active galactic nucleus (AGN) bolometric luminosity. These values are higher than usually observed in nearby active galaxies with the same bolometric luminosities and could imply a significant impact of the outflows in the evolution of the host galaxy. The excitation is higher in the NK - that correlates with extended X-ray emission, indicating the presence of hotter gas - than in the SK, supporting a scenario in which an obscuring dust lane is blocking part of the AGN radiation to reach the southern region of the galaxy.