Radio observations over the last two decades have provided evidence that diffuse synchrotron emission in the form of megaparsec-scale radio halos in galaxy clusters is likely tracing regions of the intracluster medium where relativistic particles are accelerated during cluster mergers. In this paper we present results of a survey of 14 galaxy clusters carried out with the 7-element Karoo Array Telescope at 1.86 GHz, aimed to extend the current studies of radio halo occurrence to systems with lower masses (M$_\rm 500 > 4\times10^14$ M$_\odot$). We found upper limits at the $0.6 - 1.9 \times 10^24$ Watt Hz$^-1$ level for $\sim 50\%$ of the sample, confirming that bright radio halos in less massive galaxy clusters are statistically rare.
A KAT-7 view of a low-mass sample of galaxy clusters
DALLACASA, DANIELE;CUCITI, VIRGINIA;
2016
Abstract
Radio observations over the last two decades have provided evidence that diffuse synchrotron emission in the form of megaparsec-scale radio halos in galaxy clusters is likely tracing regions of the intracluster medium where relativistic particles are accelerated during cluster mergers. In this paper we present results of a survey of 14 galaxy clusters carried out with the 7-element Karoo Array Telescope at 1.86 GHz, aimed to extend the current studies of radio halo occurrence to systems with lower masses (M$_\rm 500 > 4\times10^14$ M$_\odot$). We found upper limits at the $0.6 - 1.9 \times 10^24$ Watt Hz$^-1$ level for $\sim 50\%$ of the sample, confirming that bright radio halos in less massive galaxy clusters are statistically rare.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
