A multifrequency study of the large radio galaxies 3C46 and 3C452

TL;DR

This study uses low and high-frequency radio observations to estimate the spectral ages of large radio galaxies 3C46 and 3C452, finding ages of 15 and 27 million years and no evidence of older activity cycles.

Contribution

It provides new spectral age estimates for 3C46 and 3C452 using multifrequency data and investigates the presence of relic emission at low frequencies.

Findings

Spectral ages are approximately 15 and 27 million years.

No evidence of diffuse emission from earlier activity cycles.

Spectra near hotspots are consistent with straight spectra with steep injection indices.

Abstract

We present low-frequency observations starting from ~150 MHz with the Giant Metrewave Radio Telescope (GMRT), and high-frequency observations with the Very Large Array (VLA) of two large radio galaxies 3C46 and 3C452. These observations were made with the objectives of estimating their spectral ages and examining any evidence of diffuse extended emission at low radio frequencies due to an earlier cycle of activity. While no evidence of extended emission due to an earlier cycle of activity has been found, the spectral ages have been estimated to be ~15 and 27 Myr for the oldest relativistic plasma seen in the regions close to the cores for 3C46 and 3C452 respectively. The spectra in the vicinity of the hotspots are consistent with a straight spectrum with injection spectral indices of ~1.0 and 0.78 respectively, somewhat steeper than theoretical expectations.