Speaker
Description
There are still many open questions and uncertainties regarding the evolution of radio galaxies. Compact AGNs, such as Gigahertz Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) sources, are thought to be the precursors of classical double-lobed radio galaxies. However, some studies suggest their evolution may be more complex than previously assumed. These sources can be temporarily frustrated by their host environments or even be short-lived and transient. Low-frequency radio observations provide a unique opportunity to probe the oldest plasma and investigate the early stages of activity and dynamics in young AGNs.
In this study, we present the results of an analysis of a sample of CSS sources that remain unresolved in the FIRST and LoTSS surveys. Using the LOFAR-VLBI pipeline, we resolved their structures into components at 150 MHz and compared them with higher-frequency observations from MERLIN and the VLA. In several cases, we detected 150 MHz emission from lobes that are not visible at higher frequencies. We modelled the synchrotron spectra of these components to investigate absorption processes and estimate source ages. Furthermore, we report significant asymmetries in the brightness of radio lobes in some sources and discuss potential physical explanations for this phenomenon in light of our new observations.
