Tomasz Nowakowski is a writer for Phys.org.
The LOFAR Two-meter Sky Survey (LoTSS) has detected a new giant radio galaxy. The largest GRG found to date is named Alcyoneus. A paper published February 11 on the arXiv pre-print repository details the finding.
The projected linear length of the GRG is more than 2.3 million light years. They are grown in low density environments. Astronomers study the formation and evolution of radio sources with the help of GRGs.
Out of a thousand GRGs detected, only ten exceed 10 million light years in size. J1420-0545 is the largest one with a projected length of 16 million light years. The rest of the megaparsec-scale radio galaxies are thought to be the largest single-galaxy-caused phenomena in the universe.
A team of scientists from the Netherlands have found a giant radio galaxy that is the largest one of the other ones. The finding was made by analyzing the second data release.
The latest version of the LOFAR's Northern Sky survey is reprocessed by subtracting angularly compact sources and 90 degree resolution. The researchers wrote in the paper that the resulting images allow them to explore a new sensitivity regime for radio galaxy lobes and thus represent promising data to search for unknown GRGs.
A giant radio galaxy with a central component and two outer components was identified by the astronomer. They found that this GRG Alcyoneus has a projected proper length of 16.26 million light years, while its true proper length was estimated to be 16.43 million light years. It is the largest known structure made by a single galaxy.
The research states that Alcyoneus has a total luminosity density of some 80 YW/Hz, which is typical for giant radio galaxies. The host of the GRG is an elliptical galaxy with a stellar mass of approximately 240 billion solar mass and a super massive black hole.
The authors of the paper pointed out that Alcyoneus has a low stellar mass and low SMBH mass. They say that there is no correlation between radio galaxy length and low-frequency radio power.
If the observed state is representative of the source over its lifetime, neither is high radio power necessary to grow large giants.
More information: Martijn S.S.L. Oei et al, The discovery of a radio galaxy of at least 5 Mpc. arXiv:2202.05427v1 [astro-ph.GA], arxiv.org/abs/2202.05427The Science X Network will be launched in 2022.
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