A multifrequency study of giant radio sources I. Low-frequency Giant Metrewave Radio Telescope observations of selected sources

TL;DR

This study uses low-frequency GMRT and high-frequency VLA observations to analyze giant radio sources, estimating magnetic fields, spectral indices, and environmental asymmetries to understand their physical properties and activity history.

Contribution

It provides multifrequency magnetic field estimates, examines core spectral indices, and investigates environmental asymmetries in giant radio sources, offering new insights into their physical conditions.

Findings

Magnetic field estimates vary by up to a factor of 3 across methods.

Inverse-Compton losses dominate over synchrotron losses in these sources.

Environments are often asymmetric on scales of about 1 Mpc.

Abstract

We present low-frequency observations with the Giant Metrewave Radio Telescope (GMRT) of a sample of giant radio sources (GRSs), and high-frequency observations of three of these sources with the Very Large Array (VLA). From multifrequency observations of the lobes we estimate the magnetic field strengths using three different approaches, and show that these differ at most by a factor of $\sim$3. For these large radio sources the inverse-Compton losses usually dominate over synchrotron losses when estimates of the classical minimum energy magnetic field are used, consistent with earlier studies. However, this is often not true if the magnetic fields are close to the values estimated using the formalism of Beck & Krause. We also examine the spectral indices of the cores and any evidence of recurrent activity in these sources. We probe the environment using the symmetry parameters of these sources and suggest that their environments are often asymmetric on scales of $\sim$1 Mpc, consistent with earlier studies.