A team of astronomers, led by Wonki Lee from Yonsei University in Seoul, South Korea, recently embarked on a fascinating exploration of the galaxy cluster Abell 514 (A514) using the upgraded Giant Metrewave Radio Telescope (uGMRT). Their discoveries, outlined in a paper published on October 2nd on the arXiv pre-print server, shed light on a remarkable phenomenon within this merging galaxy cluster.
Galaxy clusters are monumental celestial structures, comprising thousands of galaxies bound together by the force of gravity. Their study can provide valuable insights into the formation and evolution of the universe’s large-scale structure.
Abell 514, denoted as A514, is a merging galaxy cluster with a redshift of approximately 0.07, initially discovered back in 1958. It possesses a staggering mass equivalent to about 300 trillion times that of our Sun, an overall temperature of 3.8 keV, and an estimated metallicity level of 0.22. Previous observations of A514 have unveiled its rich morphology and the presence of numerous extended radio sources.
The astronomers employed uGMRT to carry out radio observations across different frequency bands, namely Band 2 (125−250 MHz), Band 3 (250−500 MHz), and Band 4 (550−850 MHz), with varying on-source integration times ranging from 3.5 to 4.3 hours.
One of the standout discoveries was the detection of radio emissions from PKS 0446-20, one of three radio galaxies within A514. These emissions emanate from two radio lobes originating from the active galactic nucleus (AGN) and extending towards the southern periphery. Astonishingly, the largest linear measurement of this bent jet extends to a colossal 2.3 million light-years.
The uGMRT images unveiled a fascinating connection between two radio lobes and a north-south structure spanning 1,300 light-years, aptly named “the bridge.” The bridge, in turn, links to a 1,000-light-year-long “arc” that curves towards the cluster’s center. The arc’s eastern end even appears to make contact with the northern tip of a 1,300-light-year-long tail.
Furthermore, the observations revealed a discontinuity in X-ray surface brightness and high polarization at the precise location of the extended radio emissions in A514. According to the paper’s authors, this peculiar phenomenon arises from the redistribution of jet plasma along the cold front generated by a recent merger of clusters.
Intriguingly, the scientists postulate that a passive plasma bubble, introduced during an off-center cluster merger, experiences stretching along the cold front as the merger progresses. This stretching process results in the creation of extended radio emissions akin to those observed within A514. In the later stages of the merger, the bubble redistributes towards the cluster’s outer edge, with its elongation aligning tangentially to the cluster.
In summary, this groundbreaking study employing uGMRT has unveiled a captivating radio phenomenon within the galaxy cluster A514, shedding light on the intricate dynamics of celestial structures and their evolution in the cosmos.