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Astronomers have uncovered an astonishing new colossal radio galaxy featuring plasma jets 32 times the scale of our Milky Way.
Stretching 3.3 million light-years from one end to the other, this cosmic megastructure was detected by the MeerKAT telescope in South Africa and dubbed Inkathazo – which translates to ‘trouble’ in the African Xhosa and Zulu tongues – due to the challenges involved in comprehending the physics behind it.
Scientists anticipate that their “thrilling and unforeseen discovery,” published today in Monthly Notices of the Royal Astronomical Society, will illuminate the enigmatic origins and development of some of the colossal structures in the Universe.
Giant radio galaxies (GRGs) are immense cosmic entities emitting jets of hot plasma spanning millions of light-years across the expanse between galaxies. These plasma jets, which shine in radio frequencies, are fueled by supermassive black holes located at the core of galaxies.
Previously, GRGs were considered relatively uncommon. However, a new wave of radio telescopes, including South Africa’s MeerKAT, has altered this perspective.
“The quantity of GRG discoveries has skyrocketed over the last five years, thanks to powerful new telescopes such as MeerKAT,” stated Kathleen Charlton, a Master’s student at the University of Cape Town and the lead author of the recent study.
“Research centered on GRGs is evolving so swiftly that it’s becoming challenging to keep pace. It’s incredibly thrilling!”
A spectral age map of ‘Inkathazo’. Cyan and green represent younger plasma, while purple denotes older plasma.
K.K.L Charlton (UCT), MeerKAT, HSC, CARTA, IDIA
She further commented: “We named this colossal galaxy ‘Inkathazo,’ translating to ‘trouble’ in isiZulu and isiXhosa since it has posed some challenges in deciphering the physics behind what’s occurring here.
“It exhibits dissimilar characteristics compared to many other giant radio galaxies. For instance, the plasma jets take on an unusual form: instead of running straight across from end to end, one of the jets is curved.”
Inkathazo is also situated at the center of a cluster of galaxies, rather than being relatively isolated, which should complicate the growth of its plasma jets to such large dimensions.
“This is an exciting and surprising discovery,” remarked Dr Kshitij Thorat, a co-author of the study from the University of Pretoria.
“Finding a GRG within a cluster environment raises intriguing questions about the impact of environmental interactions on the formation and progression of these gigantic galaxies.”
In an effort to delve deeper into this cosmic puzzle, the researchers utilized MeerKAT’s remarkable capabilities to produce some of the highest-resolution spectral age maps ever created for GRGs. These maps trace the plasma’s age across various segments of the GRG, offering insights into the physical processes at work.
The findings showcased fascinating complexities in Inkathazo’s jets, with some electrons receiving unexpected boosts of energy. The researchers theorize that this may occur when the jets collide with heated gas found in the voids between galaxies within a cluster.
“This discovery has provided us a singular chance to examine GRG physics in exquisite detail,” said Thorat. “The results challenge existing theories and indicate that much of the intricate plasma physics influencing these extreme galaxies remains misunderstood.”
South Africa’s MeerKAT telescope.
South African Radio Astronomy Observatory
Most identified GRGs have been located at northern latitudes through European telescopes, while the southern sky remains relatively uncharted for such massive entities. Nevertheless, Inkathazo is not solitary. It is the third GRG to be identified in a small area of the sky, approximately the size of five full moons, that astronomers have dubbed ‘COSMOS’.
When an international cohort of astronomers known as the ‘MIGHTEE’ collaboration observed COSMOS using the MeerKAT telescope, they promptly discovered the other two GRGs and shared their findings in 2021.
Inkathazo was observed more recently during follow-up studies with MeerKAT, which operates under the South African Radio Astronomy Observatory.
“The fact that we revealed three GRGs by directing MeerKAT at a single expanse of sky illustrates that a vast treasure trove of undiscovered GRGs likely exists in the southern hemisphere” stated Dr Jacinta Delhaize, a researcher at the University of Cape Town, who spearheaded the 2021 publication.
“MeerKAT possesses remarkable power and is situated perfectly, making it excellently positioned to discover and learn more about them.”
As a forerunner to the Square Kilometre Array (SKA) set to commence operations by the end of this decade, MeerKAT delivers unprecedented sensitivity and resolution, facilitating discoveries like that of Inkathazo.
“We’re entering a fascinating era of radio astronomy,” commented Dr Delhaize. “While MeerKAT has propelled us further than we have ever been, the SKA will enable us to push these limits even further and hopefully unravel some mysteries surrounding enigmatic entities such as giant radio galaxies.”
ENDS
Media contacts
Sam Tonkin
Royal Astronomical Society
Mob: +44 (0)7802 877 700
Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)7802 877 699
Scientific contacts
Kathleen Charlton
University of Cape Town
Tel: +27 (0)832 603 855
Dr Jacinta Delhaize
University of Cape Town
A/Prof Kshitij Thorat
University of Pretoria
Images and captions
Inkathazo giant radio galaxy
Caption: The recently-discovered giant radio galaxy ‘Inkathazo’. The illuminated plasma jets, as captured by the MeerKAT telescope, are depicted in red and yellow. The starlight from adjacent galaxies is visible in the background.
Credit: K.K.L Charlton (UCT), MeerKAT, HSC, CARTA, IDIA
Inkathazo spectral
Caption: A spectral age map of ‘Inkathazo’. Cyan and green illustrate younger plasma, whereas purple signifies older plasma.
Credit: K.K.L Charlton (UCT), MeerKAT, HSC, CARTA, IDIA
MeerKAT telescope
Caption: South Africa’s MeerKAT telescope.
Credit: South African Radio Astronomy Observatory
Further information
The paper ‘A spatially-resolved spectral analysis of giant radio galaxies with MeerKAT’ by Kathleen Charlton et al. has been released in Monthly Notices of the Royal Astronomical Society. DOI: 10.1093/mnras/stae2543
Notes for editors
About the MIGHTEE collaboration
This research was co-authored by several members of the international MIGHTEE collaboration of astronomers, spearheaded by Professor Matt Jarvis (University of Oxford) and with significant contributions from Dr Ian Heywood (University of Oxford).
The MeerKAT International Gigahertz Tiered Extragalactic Exploration (MIGHTEE) survey is a
Extensive Survey Initiative being carried out with the MeerKAT telescope. Its primary objective is to examine the creation and development of galaxies. For additional details, visit https://www.mighteesurvey.org/
About MeerKAT
The MeerKAT telescope is situated in the Karoo area of South Africa and consists of 64 radio antennas. It is overseen by the South African Radio Astronomy Observatory (SARAO), which is a division of the National Research Foundation. More information can be found at: https://www.sarao.ac.za/science/meerkat/
About the Royal Astronomical Society
The Royal Astronomical Society (RAS), established in 1820, fosters and supports the exploration of astronomy, solar-system science, geophysics, and related scientific fields.
The RAS arranges academic meetings, publishes global research and review journals, acknowledges exceptional accomplishments through the presentation of medals and awards, maintains a vast library, advocates for education through grants and outreach programs, and represents UK astronomy on both national and international stages. With over 4,000 members (Fellows), a third of whom are based abroad, it includes scientific investigators from universities, observatories, and laboratories as well as historians of astronomy and others.
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