A study involving astronomers from around the world has discovered the rare massive galaxies, known as Giant Radio Galaxies, the first of which was discovered 30 years ago. These massive cosmic monsters, ranging from just over 2.3 million light-years across, harbour one galaxy—ASKAP J0107–2347—that measures an eye-watering 12.4 million light-years, making even the Milky Way’s 105,700 light-year girth look puny in comparison. ASI J0107–2347 is particularly interesting because its rare ‘overlapping lobe’ morphology is indicative of a history of episodic black hole activity. These findings provide new insights into the life cycle of supermassive black holes and the dynamics of radio jet propagation.
ASKAP Maps Black Hole Jet History in Giant Radio Galaxies with Unmatched Deep-Sky Resolution
As per a Space.com report, the research led by Western Sydney University’s Baerbel Silvia Koribalski reveals that these galaxies likely owe their size to episodic black hole activity. Active accreting supermassive black holes at the centres of galaxies can generate jets that inflate radio lobes that fill millions of light-years. Galaxies such as ASKAP J0107–2347 have inner and outer lobes, which suggest some jet activity in the past and present.
The ASKAP’s wide-field view, thanks to its checkerboard-like phased array feeds, allows astronomers to cover up to 30 square degrees of sky each time they observe — a record scope for radio astronomy.
Radio Galaxies are developed from taking matter and ingesting it into a supermassive black hole, which results in giant radio lobes. Once the black hole “falls asleep”, the lobes fade unless they are rejuvenated by a galaxy merger. ASKAP’s survey of the region around the Sculptor galaxy turned up new, faint lobes, offering a time sequence of these dynamic objects.
Deep, sensitive surveys such as ASKAP are critical to uncovering diffuse, low-energy lobes that escape shallower ones. These shapes are formed by “cluster weather” in dense galaxy clusters, producing intricate shapes such as jellyfish tails or corkscrew patterns. The high resolution and sensitivity of ASKAP make it a new way of studying these shapes for astronomers.
ASKAP J0107–2347 uncovers an ancient black hole event and unearths relics of galactic prehistory. More of these double-lobed Giant Radio Galaxies could be discovered in future ASKAP surveys, helping researchers to gain insight into the life cycle of active galactic nuclei. A preprint of the findings appears on arXiv.
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