MRC 2011-298 radio images

We carried out a detailed spectral analysis sampling different spatial scales. Integrated radio spectra, spectral index maps, radio colour-colour diagrams, and radiative age maps of both the active lobes and prominent wings were employed to test the origin of the source. We confirm a progressive spectral steepening from the lobes to the wings.

The maximum radiative age of the source is ~80Myr, with the wings being older than the lobes by >=30Myr in their outermost regions. The observed properties are in line with an abrupt reorientation of the jets by ~90deg from the direction of the wings to their present position. This formation mechanism is further supported by the comparison with numerical simulations in the literature, which additionally highlight the role of hydrodynamic processes in the evolution of large wings such as those of MRC 2011-298.

It is plausible that the coalescence of supermassive black holes could have triggered the spin-flip of the jets. Moreover, we show that the S-shape of the radio jets is likely driven by precession with a period of P~10Myr.