Low frequency results for the radio galaxies and the role of GMRT

TL;DR

This study uses GMRT to analyze low-frequency radio emissions from galaxies, revealing two classes of sources with different spectral aging behaviors, challenging existing models and highlighting GMRT's role in uncovering new astrophysical insights.

Contribution

It identifies two classes of radio galaxies based on low-frequency spectral properties, suggesting the need to revise spectral aging models and demonstrating GMRT's effectiveness in low-frequency astrophysics.

Findings

Two classes of sources based on spectral aging behavior

Flatter spectra in low-surface-brightness features

Rapid fading of low-frequency emission in some sources

Abstract

We have studied several radio galaxies at low radio frequencies using GMRT. Our prime motivation to detect faint radio emission at very low frequencies due to low energy electrons. Our results provide evidence that there exists two classes of sources on morphological grounds. The first class is explained by the simple picture of spectral electron ageing but in the second class the low-frequency synchrotron emission fades (nearly) as rapidly as high-frequency synchrotron emission. In addition, in several sources, the spectra of low-surface-brightness features are flatter than the spectra of high-surface-brightness features, which suggests that either the simple picture of spectral electron ageing needs revision or we need to re-examine the formation mechanism of such sources. The images and statistics, and the relevance of these results along with the role of GMRT in exploring several unknowns are presented.