Highly extinguished emission line outflows in the young radio source PKS 1345 + 12

We present new, intermediate resolution spectra (∼ 4 Å) of the compact radio source PKS 1345+12 (4C 12.50, z = 0.122) with large spectral coverage (∼ 4500 Å). Our spectra clearly show extended line emission up to ∼ 20 kpc from the nucleus. This is consistent with the asymmetric halo of diffuse emission observed in optical and infrared images. At the position of the nucleus we observe complex emission line profiles. Gaussian fits to the [O III] emission lines require 3 components (narrow, intermediate and broad), the broadest of which has FWHM ∼ 2000 km s and is blue shifted by up to ∼ 2000 km s with respect to the halo of the galaxy and HI absorption. We interpret this as material in outflow. We find evidence for high reddening and measure E(B-V) > 0.92 for the broadest, most kinematically disturbed component. This corresponds to an actual Hβ flux 130 times brighter than that observed. From our model for [S II]λλ6716,6731 we estimate electron densities of ne <150 cm , ne >5300 cm and ne >4200 cm −3 for the regions emitting the narrow, intermediate and broad components respectively. We calculate a total mass of line emitting gas of Mgas < 10 6 M⊙. Not all emission line profiles can be reproduced by the same model with [O I]λλ6300,6363 and [S II]λλ6716,6731 requiring separate, unique models. We argue that PKS 1345+12 is a young radio source whose nuclear regions are enshrouded in a dense cocoon of gas and dust. The radio jets are expanding through this cocoon, sweeping material out of the nuclear regions. Emission originates from three kinematically distinct regions though gradients (e.g. in density, ionisation potential, acceleration etc) must exist across the regions responsible for the emission of the intermediate and broad components.