Reassessment of an origin of the radio structure of J1420-0545

Abstract: In this paper, we test the possibility that the structure of the largest radio galaxy J1420-0545 may have been formed by restarted rather than primary jet activity. This hypothesis was motivated by the unusual morphological properties of the source consisting of two edge-brightened, narrow, highly collinear, and symmetric lobes, thus suggesting an almost ballistic propagation of powerful jets into a particularly low-density external medium. New observations made with the VLA together with the currently available GLEAM and TGSS ADR1 data releases allow the detection of an excess emission at low frequencies. An extracted part (88 MHz - 200 MHz) of the spectrum of the emission is fitted with the DYNAGE model, giving a forecast for the environmental conditions and the energetic requirements for the presumed old cocoon related to a preceding epoch of jet activity.