news

23 million light years！

this is the longest star ever discovered by astronomers.black hole jet pairit is not just as big as a solar system or a galaxy;this is equivalent to lining up 140 galaxies.。

this jet giant structure is nicknamed "porphyrion"（Porphyrion）, taken from the giants in greek mythology. it dates back to 6.3 billion years in our universe's history. these violent outflows are ejected from above and below a supermassive black hole at the center of a distant galaxy.the total output power is equivalent to trillions of suns。

in addition to porphyrion, the team has discovered more, including more than 8,000 jet pairs. the research has been published in astronomy & astrophysics.

cosmic behemoth

as early as 2018, the team began using lofar(lofar low frequency array)radio telescopebut as they searched for faint filaments in radio images, they noticed several strikinglong jet system。

prior to the discovery of porphyrion, the largest confirmed jet system was alcyoneus.（Alcyoneus）, which was also discovered by the same team in 2022. alcyoneus spans the size of about 100 milky way galaxies.(for comparison, the centaurus a jet system, the closest to earth, spans 10 milky way galaxies.)

to systematically search for more hidden jets, the team of researchers searched radio images by eye, used machine learning tools to scan for faint signs of jets, and enlisted the help of citizen scientists around the world.there are more than 10,000 faint megastructures, and the porphyrion jet system is the largest one ever discovered.。

the photo shows the longest known pair of black hole jets. (photo/lofar collaboration/martijn oei (caltech))

the latest findings suggest that these giant jet systems may have a greater impact on galaxy formation in the young universe than previously thought.porphyryon existed in an earlier era, when the filaments that connected and nourished the galaxies(the so-called cosmic web)closer than nowthis means that giant jets like porphyryon can span a much larger portion of the cosmic web than jets in the local universe.

in astronomy, scientists believe that galaxies and their central black holes evolve together, as a key factor is that jets can spread enormous amounts of energy, affecting the growth of their host galaxies and other nearby galaxies. now, this new discovery shows that their influence extends much further than we thought.

lurking in the past

to find porphyryon's galaxy, the team used india's large meterwave radio telescope（GMRT）, dark energy spectrometer（DESI）keck observatory（WMKO）the results showed that it originated from a huge galaxy, about 10 times more massive than the milky way, 7.5 billion light-years away.

india's large meterwave radio telescope (gmrt). (photo/caltech)

so far, these giant jet systems look like a recent phenomenon. if distant jets like these can reach the scale of the cosmic web, then every location in the universe has likely been affected by black hole activity at some point.

they also noted that porphyryon came from a so-called radiative-mode active black hole, rather than a jet-mode black hole. when a supermassive black hole becomes active,in other words,that is, when their huge gravity pulls on and heats the surrounding matter, they release energy in the form of radiation or jets.

generally speaking, radiating-mode black holes are more common in the young, distant universe, while jet-mode black holes are more common in the present-day universe.the fact that such a huge jet came from a radiative mode black hole was completely unexpected, as astronomers did not know that this mode could produce such a large and powerful jet.since porphyryon is located in the distant universe, where radiation-mode black holes are omnipresent, it is likely that there are more giant jets to be discovered.。

unsolved mysteries

it's unclear how these jets are able to stably extend so far beyond their host galaxies. this is puzzling because the study also suggests that the environments where these giants originate are nothing special.

one possible explanation is that there is an unusually long and stable accretion event around the central supermassive black hole., which keeps the jet active for so long and ensures that the jet points in the same direction during this time.

next, the team hopes to gain a deeper understanding of how these megastructures affect the environment around them.