Led by Pune’s uGMRT, international radio telescopes capture unseen sides of cluster galaxy Abell 2256
Pune-based upgraded Giant Metrewave Radio Telescope (uGMRT) was among the five key global facilities that together allowed astronomers to capture and stitch together images revealing hitherto unseen areas of a nearby galaxy cluster named Abell 2256.
Additionally, the uGMRT, operated by TIFR – National Centre for Radio Astrophysics (NCRA), allowed scientists to identify and map an unusually high number of radio galaxies, most with monstrous supermassive black holes located in their centres that possessed ghostly morphologies, too.
Supermassive black hole nuclei and collisions are among the commonest causes for the formation of galaxy clusters like the Abell 2256. During such processes, energy is released in the form of shock waves and turbulence. In turn, electrons get accelerated to high-speed jets in the presence of hot gas, which then emit radio waves upon encountering a magnetic field.
Located at about 1,000 million light-years away from Earth, Abell 2256 is a rich galaxy cluster in the Abell catalogue. This cluster is of particular interest to astronomers as it is distinguished for its complex structures and high activity. So much so that there have been known mergers between its own member galaxies resulting in the release of humongous amounts of energy.
The team of scientists led by Kamlesh Rajpurohit from the University of Bologna and collaborators from institutions in Italy, Germany, the Netherlands and the USA used collective capacities of the uGMRT, LOwer-Frequency ARray (LOFAR) in the Netherlands, the Karl G Jansky Very Large Array (VLA) in USA, and the space-based observatories – Chandra and the XMM-Newton – to derive the most detailed image of Abell 2256. The results, published in the journal of Astronomy and Astrophysics, stated that the images obtained from the Pune-based facility divulged newer emission features. Also, it is for the first time ever that the scientific community learned of large and extended radio emissions.
“Before uGMRT observations, there were no hints of the presence of such large-scale radio emissions in this system. We were also surprised to see the filamentary morphology below the GigaHertz frequencies,” said Rajpurohit.
Further, the scientists shared that the images helped them decipher how radio emissions are extended longer at low frequencies. For the first time, regions were detected where shocks and turbulences resulting in particle acceleration occur.
Professor Yashwant Gupta, centre director, NCRA that operates the uGMRT, said the uGMRT’s sensitivity offered a window into the universe at low frequencies and high resolution. “This helped reveal previously undetected regions and structures such as the extended radio emission in several objects like the Abell 2256,” he said.
Further, the capabilities of the uGMRT, the astronomers said, so far helped them map at least 50 such galaxies portraying unusual morphologies that would have remained undetected. The same team is currently undertaking more observations and data analysis about such clusters displaying complex structures.
