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The Event Horizon Telescope peered into the very base of a blazar's relativistic jet and found that it is bent almost at a right angle to the large-scale outflow, and we are looking almost straight down its barrel.
In April 2021, the antennas of the Event Horizon Telescope (EHT)—a global network of millimeter-wave radio telescopes — zeroed in on a tiny spot in the constellation Virgo. This was the active galactic nucleus of galaxy 3C 279, located 16,5 megaparsecs away — one of the brightest and most variable blazars. From its center blasts a relativistic jet, a narrow stream of plasma accelerated nearly to the speed of light. At such a distance, details at the scale of tens of microarcseconds evaded all instruments, and only the EHT could finally resolve the base of this beam. The picture was stunning: the jet is not stretched along the usual direction but sharply bends almost at a right angle, like a spotlight aimed straight into your eyes, with a slight twist right at the source.
The bend was no random artifact. Image reconstruction with three independent algorithms at 230 GHz revealed a stable structure of several bright spots aligned north–south. The central component C2 and its satellites moved away from a stationary 'root' C0 with an apparent speed exceeding the speed of light tenfold—$β_{app}$ ≈ 10,2. This illusion, known as superluminal motion, stems directly from relativistic geometry: the true speed β relates to the apparent speed and angle θ by a simple relation (see formula). Data from Very Long Baseline Interferometry (VLBI) at 43 and 86 GHz confirmed that the viewing angle is less than 0,3 degrees. That's like trying to discern a coin from several kilometers away. The jet points straight at us, and its ultra-relativistic motion (Lorentz factor Γ ≥ 10,3) makes the emission hundreds of times brighter thanks to the Doppler factor δ ~ 10–20.
Such morphology is not unique to 3C 279. Similar transverse bends have been seen in blazars OJ 287, 3C 345, CTA 102, and others. Over several years — in 2011, 2017, and 2021—the structure persisted, pointing to a stable mechanism rather than a transient flare.
The underlying physics is even more puzzling. To radiate at 230 GHz, the plasma must be heated to a brightnesstemperature around 5×10⁹ K, but in the rest frame this figure drops to a modest (1–17)×10⁹ K — below the inverse Compton limit. This means the jet is optically thin, and astronomers are seeing not just its surface but matter deep inside. The extreme viewing angle amplifies the signal according to the second formula, where the plasma flow acts as a natural amplifier. The strong bend at the very base, on scales of about 5000 gravitational radii, demands a revision of models. Likely culprits: magnetic reconnection near the supermassive black hole, interaction with the interstellar medium, or development of instabilities in the flow erupting from the accretion disk.
Blazar 3C 279 becomes a natural laboratory for extreme physics. Long-term observations with an expanded telescope network (the ngEHT project) and at higher frequencies (345 GHz) will help distinguish between competing hypotheses — regular jet precession, stochastic kinks, or kinetic instabilities. The ultimate goal is understanding how magnetic fields and black hole rotation launch collimated jets that power entire galaxy clusters. For now, Earth remains in the beam of this cosmic spotlight: shift by a fraction of a degree and the source would vanish. Discovered in 1971 as one of the first variable radio galaxies, 3C 279 today confirms a half-century-old hunch: we are staring almost straight down the barrel.
3C 279 is one of the first blazars discovered (in 1971). Its variability hinted to astronomers that the jet was aimed almost directly at Earth. Half a century later, EHT confirmed: the angle is less than a degree, like trying to examine a coin from several kilometers away.
In Stanisław Lem's novel "Fiasco", humans encounter an alien civilization that communicates with tightly focused beams. The situation is somewhat reminiscent of a blazar: shift slightly off the beam and the source becomes invisible.
