The peculiar radio galaxy 4C 35.06: a case for recurrent AGN activity?

Abstract

Using observations obtained with the LOw Fequency ARray (LOFAR), the Westerbork Synthesis Radio Telescope (WSRT) and archival Very Large Array (VLA) data, we have traced the radio emission to large scales in the complex source 4C 35.06 located in the core of the galaxy cluster Abell 407. At higher spatial resolution (~4"), the source was known to have two inner radio lobes spanning 31 kpc and a diffuse, low-brightness extension running parallel to them, offset by about 11 kpc (in projection). At 62 MHz, we detect the radio emission of this structure extending out to 210 kpc. At 1.4 GHz and intermediate spatial resolution (~30"), the structure appears to have a helical morphology. We have derived the characteristics of the radio spectral index across the source. We show that the source morphology is most likely the result of at least two episodes of AGN activity separated by a dormant period of around 35 Myr. The AGN is hosted by one of the galaxies located in the cluster core of Abell 407. We propose that it is intermittently active as it moves in the dense environment in the cluster core. Using LOFAR, we can trace the relic plasma from that episode of activity out to greater distances from the core than ever before. Using the the WSRT, we detect HI in absorption against the center of the radio source. The absorption profile is relatively broad (FWHM of 288 km/s), similar to what is found in other clusters. Understanding the duty cycle of the radio emission as well as the triggering mechanism for starting (or restarting) the radio-loud activity can provide important constraints to quantify the impact of AGN feedback on galaxy evolution. The study of these mechanisms at low frequencies using morphological and spectral information promises to bring new important insights in this field.

10 pages, 6 figures. Accepted to A&A

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• The best of both worlds: Combining LOFAR and Apertif to derive resolved radio spectral index images
• The Dynamics and Energetics of Remnant and Restarting RLAGN
• Studying the late evolution of a radio-loud AGN in a galaxy group with LOFAR
• Effect of richness on AGN and star formation activities in SDSS galaxy groups
• Unveiling the AGN in IC 883: discovery of a parsec-scale radio jet
• The peculiar WAT NGC 2329 with Seyfert/FR I-like radio lobes
• Chandra view of Abell 407: the central compact group of galaxies and the interaction between the radio AGN and the ICM
• HI absorption associated with Norma's brightest cluster galaxy
• The radio source in Abell 980: A Detached-Double-Double Radio Galaxy?
• A Morphological Identification and Study of Radio Galaxies from LoTSS DR2. I. The "Winged'' Radio Galaxies