We present detailed submillimeter-through centimeter-wave observations of the extraordinary extragalactic transient AT2018cow. The apparent characteristicsthe high radio luminosity, the rise and long-lived emission plateau at millimeter bands, and the sub-relativistic velocity -have no precedent. A basic interpretation of the data suggests E k 4 × 10 48 erg coupled to a fast but sub-relativistic (v ≈ 0.13c) shock in a dense (n e ≈ 3 × 10 5 cm −3 ) medium. We find that the X-ray emission is not naturally explained by an extension of the radio-submm synchrotron spectrum, nor by inverse Compton scattering of the dominant blackbody UVOIR photons by energetic electrons within the forward shock. By ∆t ≈ 20 days, the X-ray emission shows spectral softening and erratic inter-day variability. Taken together, we are led to invoke an additional source of X-ray emission: the central engine of the event. Regardless of the nature of this central engine, this source heralds a new class of

Here, we describe the Compact Array Broad‐band Backend (CABB) and present first results obtained with the upgraded Australia Telescope Compact Array (ATCA). The 16‐fold increase in observing bandwidth, from 2 × 128 to 2 × 2048 MHz, high‐bit sampling and the addition of 16 zoom windows (each divided into further 2048 channels) provide major improvements for all ATCA observations. The benefits of the new system are: (1) hugely increased radio continuum and polarization sensitivity as well as image fidelity; (2) substantially improved capability to search for and map emission and absorption lines over large velocity ranges; (3) simultaneous multi‐line and continuum observations; (4) increased sensitivity, survey speed and dynamic range due to high‐bit sampling and (5) high‐velocity resolution, while maintaining full polarization output. The new CABB system encourages all observers to make use of both spectral line and continuum data to achieve their full potential. Given the dramatic increase of the ATCA capabilities in all bands (ranging from 1.1 to 105 GHz) CABB enables scientific projects that were not feasible before the upgrade, such as simultaneous observations of multiple spectral lines, on‐the‐fly mapping, fast follow‐up of radio transients (e.g. the radio afterglow of new supernovae) and maser observation at high‐velocity resolution and full polarization. The first science results presented here include wide‐band spectra, high dynamic‐range images and polarization measurements, highlighting the increased capability and discovery potential of the ATCA.

Observations of ionized and neutral gas outflows in radio galaxies (RGs) suggest that active galactic nucleus (AGN) radio jet feedback has a galaxy-scale impact on the host interstellar medium, but it is still unclear how the molecular gas is affected. Thus, it is crucial to determine the physical conditions of the molecular gas in powerful RGs to understand how radio sources may regulate the star formation in their host galaxies. We present deep Spitzer Infrared Spectrograph (IRS) high-resolution spectroscopy of eight nearby RGs that show fast H i outflows. Strikingly, all of these H i-outflow RGs have bright H 2 mid-IR lines that cannot be accounted for by UV or X-ray heating. This strongly suggests that the radio jet, which drives the H i outflow, is also responsible for the shock excitation of the warm H 2 gas. In addition, the warm H 2 gas does not share the kinematics of the ionized/neutral gas. 4C 12.50, 3C 459, and PKS 1549-79. This shows that, contrary to the H i gas, the H 2 gas is inefficiently coupled to the AGN jet-driven outflow of ionized gas. While the dissipation of a small fraction (<10%) of the jet kinetic power can explain the turbulent heating of the molecular gas, our data show that the bulk of the warm molecular gas is not expelled from these galaxies.

Abstract. We present high-spatial resolution 21-cm H I VLA observations of the radio galaxy 3C 305 (z = 0.041). These new high-resolution data show that the ∼1000 km s −1 broad H  absorption, earlier detected in low-resolution WSRT observations, is occurring against the bright, eastern radio lobe, about 1.6 kpc from the nucleus. We use new optical spectra taken with the WHT to make a detailed comparison of the kinematics of the neutral hydrogen with that of the ionised gas. The striking similarity between the complex kinematics of the two gas phases suggests that both the ionised gas and the neutral gas are part of the same outflow. Earlier studies of the ionised gas had already found evidence for a strong interaction between the radio jet and the interstellar medium at the location of the eastern radio lobe. Our results show that the fast outflow produced by this interaction also contains a component of neutral atomic hydrogen. The most likely interpretation is that the radio jet ionises the ISM and accelerates it to the high outflow velocities observed. Our observations demonstrate that, following this strong jet-cloud interaction, not all gas clouds are destroyed and that part of the gas can cool and become neutral. The mass outflow rate measured in 3C 305 is comparable, although at the lower end of the distribution, to that found in Ultra-Luminous IR galaxies. This suggests that AGN-driven outflows, and in particular jet-driven outflows, can have a similar impact on the evolution of a galaxy as starburst-driven superwinds.