Astronomers have found the most powerful radio galaxy in the early Universe

Astronomers have confirmed the existence of a powerful radio galaxy, the light from which traveled to Earth for almost 12.5 billion years. The object turned out to be the most powerful radio galaxy known to date with a large redshift and allows us to study active galaxies in the early stages of the history of the universe. About how scientists discovered a record-breaking radio galaxy and what it told about the early Universe, see the Izvestia article.

Radio galaxies from the early Universe: What the scientists found

We are talking about the radio galaxy TXS 2354+015 with a redshift of 4.946. Scientists observe it as it was when the universe was less than 1.2 billion years old. The light from the object has been traveling to Earth for almost 12.5 billion years, making it the second-most distant radio galaxy known. The work has been published in the journal Phys.org .

Radio galaxies are active galaxies with supermassive black holes at their center. Matter falling on a black hole can lead to the appearance of powerful relativistic plasma jets, creating a large amount of radio emission. Such jets can affect star formation in the galaxy and heat the surrounding gas.

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How did you find an object that is difficult to see

TXS 2354+015 was initially discovered as a candidate in a very distant radio galaxy by the characteristic optical radiation drop. To search for such objects, the researchers combined data from deep optical observations of the Japanese Subaru telescope with radio catalogs TGSS and VLASS.

Scientists have been looking for sources that have the so-called Liman limit failure. It occurs because clouds of neutral hydrogen between the galaxy and the Earth absorb ultraviolet radiation. A bright Lyman-alpha line was detected in the spectrum of TXS 2354+015, and then a redshift along a fainter line was confirmed.

Additional checks have shown that the radio and optical sources do indeed correspond to the same object. This was indicated by the exact coincidence of their positions, the unusually high brightness in the radio range, and the expected ratio of radio and optical radiation.

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The most powerful radio galaxy: what calculations have shown

After calculating its own radio power, TXS 2354+015 turned out to be more powerful than all previously known radio galaxies with a large redshift. Its radio luminosity at 500 MHz in the galactic rest system is 6.2 × 102⁹ W/Hz. This figure exceeds the result of the previous record holder, found in a 2008 study.

The researchers also estimated the possible mass of the galaxy in which the source is located. It can be about 2 trillion times the mass of the Sun, making the object one of the brightest known galaxies. At the same time, scientists note that the estimate has significant uncertainties, in particular related to the age of the stellar population.

An unusual way of searching may open up new galaxies.

TXS 2354+015 does not meet the usual criteria for selecting radio galaxies with an ultra-cool spectrum. Its detection using an optical "dip" indicates that the standard search method may miss a significant part of such objects of the early Universe.

The researchers believe that combining deep optical observations with radio catalogs can help detect previously hidden radio galaxies. This will allow us to better estimate their actual number and study the most massive galaxies that formed in the early stages of the universe's existence.