How Astronomers Traced a 3,000-Light-Year Jet Back to Its Black Hole Source — And Why the Debate Isn't Over

On January 28, 2026, a collaboration of more than 280 scientists published results that connected the famous glowing ring around the supermassive black hole M87* to a compact emission region marking the probable base of its 3,000-light-year jet [1][2]. The finding, drawn from 2021 observations with an upgraded Event Horizon Telescope network, represents the first observational bridge between the black hole's immediate environment and the enormous outflow that has fascinated astrophysicists for decades. But the team itself characterizes the result as a "first hint" rather than a settled answer — and the path from hint to proof will require telescopes that do not yet exist [3].

The Target: M87 and Its Colossal Jet

M87* sits at the center of Messier 87, a giant elliptical galaxy in the Virgo cluster, roughly 55 million light-years from Earth [4]. The black hole has a mass of approximately 6.5 billion solar masses and became the first black hole ever directly imaged when the EHT released its iconic shadow photograph in April 2019, based on data collected in 2017 [5].

The jet streaming from M87* is one of the most studied outflows in astrophysics. Visible across the electromagnetic spectrum from radio to X-ray, it extends roughly 5,000 light-years (about 1,500 parsecs) in optical images captured by the Hubble Space Telescope, though the radio structure stretches even further [6]. Material within the jet travels at relativistic speeds — a substantial fraction of the speed of light — and the outflow carries an estimated kinetic power on the order of 10^44 ergs per second, though estimates from X-ray cavity analysis place the figure closer to 10^42–10^43 ergs per second depending on the method used [7][8].

For decades, the central question has been precise: where, exactly, does the jet begin? The ring of superheated material orbiting the black hole is one thing; the collimated beam punching thousands of light-years into intergalactic space is another. Connecting the two has been an observational gap that no instrument could bridge — until now.

What the 2021 Observations Found

The key result, published in Astronomy & Astrophysics, comes from EHT observations conducted in 2021 at a frequency of 230 GHz (a wavelength of 1.3 millimeters) [1]. By analyzing closure phases — a mathematical technique robust against station-based calibration errors — the team identified a Gaussian emission feature offset from the compact ring by approximately 320 microarcseconds in right ascension and 60 microarcseconds in declination [9]. At M87's distance, that translates to a projected separation of roughly 5,500 astronomical units, or about 0.09 light-years from the black hole [2][3].

The feature recovered approximately 60 milliJansky of flux density and aligns with the known direction of the large-scale jet [9]. The researchers interpret this as emission from the jet's base — the zone where plasma is accelerated and collimated before being flung outward at near-light speed.

Lead author Saurabh of the Max Planck Institute for Radio Astronomy described the result as "an early step toward connecting theoretical ideas about jet launching with direct observations," adding that "identifying where the jet may originate and how it connects to the black hole's shadow adds a key piece to the puzzle" [3][10].

The Enhanced Network: What Changed Since 2017

The 2017 EHT campaign that produced the first black hole image used eight telescope stations linked through Very Long Baseline Interferometry (VLBI), which combines signals from widely separated dishes to simulate an Earth-sized telescope [5]. Those observations achieved an angular resolution of roughly 20 microarcseconds — sufficient to resolve the black hole's shadow but not to detect structures at the jet base.

Source: Event Horizon Telescope Collaboration

Data as of Jan 28, 2026CSV

The 2021 campaign expanded the network to 11 stations [2]. The critical additions were the 12-meter Kitt Peak Telescope in Arizona and the NOrthern Extended Millimeter Array (NOEMA) in the French Alps [2][9]. These stations did not push the maximum baseline length further; rather, they filled in intermediate baselines — the gaps between the shortest and longest telescope separations. When paired with the Submillimeter Telescope (SMT) in Arizona and the IRAM 30-meter dish in Spain, the new stations provided sensitivity to emission structures at angular scales of approximately 250 microarcseconds and 2,500 microarcseconds, corresponding to physical scales of 0.02 parsecs and 0.2 parsecs respectively [9].

Source: Various EHT & VLBI publications

Data as of Jan 28, 2026CSV

This intermediate-scale sensitivity was the missing ingredient. The 2017 and 2018 EHT campaigns could see the compact ring and, separately, knew the large-scale jet existed from lower-frequency VLBI. But neither had the baseline coverage to detect structures bridging those two regimes [2][9]. The addition of Kitt Peak and NOEMA closed that gap.

The Physics: Blandford-Znajek and Competing Models

The dominant theoretical framework for jet launching is the Blandford-Znajek (BZ) process, proposed in 1977 [11]. In this model, magnetic field lines threading the event horizon of a spinning black hole extract rotational energy from the black hole itself, channeling it into a magnetically dominated outflow that eventually accelerates to relativistic speeds. An alternative class of models emphasizes the accretion disk rather than the black hole's spin, with magnetic fields anchored in the disk driving the outflow through magnetocentrifugal forces — sometimes called the Blandford-Payne mechanism [12].

Prior EHT polarization observations of M87* in 2021 showed a spiral pattern of polarized light consistent with strong, ordered magnetic fields near the event horizon — widely interpreted as the first significant empirical evidence favoring the BZ process [11][13]. General relativistic magnetohydrodynamic (GRMHD) simulations that incorporate the BZ mechanism reproduce the observed ring morphology, polarization structure, and jet collimation profile of M87 [12][14].

The new 2026 study does not directly confirm or refute any specific launching mechanism. The detected jet base component is consistent with the predicted location of jet emission in BZ-driven models, but the data cannot yet distinguish between a jet powered by black hole spin extraction and one driven by disk magnetic fields [9]. The compact emission is modeled as a Gaussian upper limit, not a resolved morphological structure, and the authors are explicit that additional observations are needed to constrain the jet's shape and thus discriminate between theoretical scenarios [9].

Scale and Power: M87 in Context

M87's jet ranks among the most powerful and best-studied relativistic outflows. To put it in comparative context:

Centaurus A, the nearest radio galaxy at about 13 million light-years, hosts a jet from a black hole of roughly 55 million solar masses — about 100 times less massive than M87* [15]. Despite this mass difference, EHT observations of Centaurus A published in 2021 revealed the same edge-brightened jet structure as M87 when scaled to each black hole's gravitational radius, suggesting that jet morphology follows scale-free physics tied to black hole mass [15]. Centaurus A's jet collimation begins at roughly 30–100 Schwarzschild radii and continues out to ~1,000 Schwarzschild radii [15].

M87's jet narrows from an opening angle of about 60° within 0.8 parsecs of the core to 6–7° at 12 parsecs [6][16]. This parabolic collimation profile is consistent with BZ-driven models and has been one of the strongest indirect arguments for magnetic jet launching [14].

The kinetic power carried by M87's jet represents a significant energy budget. Estimates derived from the internal pressure of jet knots place the power at ~10^44 ergs per second (roughly 10^37 watts, or about 25 billion times the Sun's luminosity) [7]. Lower estimates from X-ray cavity work by Forman et al. and others range from ~10^42 to 10^43 ergs per second [8]. This energy inflates large cavities in the surrounding X-ray–emitting gas, heating the intracluster medium and suppressing cooling flows — a process known as AGN feedback that is a central ingredient in modern galaxy formation simulations [7][8].

Whether the new jet base detection revises accepted scaling relationships between black hole mass and jet extent remains an open question. The finding is more about spatial connection — linking the ring to the jet — than about revising the jet's known length or power [9].

A Field Crowded With Attempts

The quest to identify M87's jet origin has spanned decades and multiple instruments. Radio VLBI observations at centimeter wavelengths with the Very Long Baseline Array (VLBA) have mapped the jet's parsec-scale structure since the 1990s, achieving resolutions of roughly 1,000 microarcseconds — sufficient to see the jet's body but not its root [16]. The Global Millimeter VLBI Array (GMVA), operating at 86 GHz with ALMA added as a station, pushed resolution to approximately 50 microarcseconds in 2018 and revealed a ring-like accretion structure roughly 50% larger than the 230 GHz ring, with the edge-brightened jet visibly connecting to it [17][18].

Source: OpenAlex

Data as of Jan 1, 2026CSV

That 2018 GMVA+ALMA result, published in Nature in 2023, was a significant advance: it showed the jet and accretion flow in the same image for the first time [17]. But it could not isolate a discrete jet base component. The 2021 EHT result goes one step further by identifying a specific compact emission feature offset from the ring in the jet direction [9].

Research on black hole jets has surged in recent years, with more than 51,000 papers published on the topic since 2011, peaking at 6,217 in 2023 according to OpenAlex data. The field involves dozens of research groups across institutions including the Max Planck Institute for Radio Astronomy, MIT Haystack Observatory, the Harvard-Smithsonian Center for Astrophysics, and the Academia Sinica Institute of Astronomy and Astrophysics, among many others [1][9].

How Conclusive Is the Finding?

The collaboration itself uses cautious language. The detected component is described as a "first hint" of the jet base, and the authors treat the Gaussian model as an upper limit on the jet base emission rather than a definitive measurement [3][9]. Several factors temper the conclusion:

Resolution limitations. The intermediate baselines sensitive to ~250 microarcseconds structures cannot resolve the detailed morphology of the jet base. At M87's distance, 250 microarcseconds corresponds to about 0.02 parsecs or roughly 100 Schwarzschild radii — large enough that alternative emission sites within the inner accretion zone cannot be ruled out [9].

Flux recovery. The 60 mJy detected accounts for only a fraction of the "missing flux" — emission known to exist from lower-resolution observations but undetected by the longest EHT baselines. The authors note that most missing flux originates from even larger angular scales, suggesting extended jet structure remains uncharacterized [9].

Model dependence. The jet base identification relies on closure phase modeling rather than direct imaging. Different modeling assumptions could yield different positional offsets, though the alignment with the known jet direction strengthens the interpretation [9].

No published rebuttal has contested the detection, but the astrophysics community broadly treats this as a stepping stone rather than a final answer. As the EHT collaboration itself notes, future observations incorporating ALMA and the Large Millimeter Telescope in Mexico will aim to directly image the jet launch region [2][3].

What Comes Next: The ngEHT and Beyond

The Next Generation Event Horizon Telescope (ngEHT) program plans to roughly double the number of stations worldwide, improve bandwidth, and add multi-frequency capability including 86 GHz observations alongside the current 230 GHz [19]. This expansion would dramatically improve the baseline coverage that proved critical in 2021, allowing imaging — rather than just modeling — of the jet launching zone.

Multi-frequency observations are particularly important because jet emission properties change with wavelength: the 86 GHz ring seen by GMVA+ALMA is larger than the 230 GHz ring, reflecting different optical depths in the accretion flow [17][18]. Simultaneous imaging at both frequencies could disentangle jet base emission from the surrounding accretion environment.

Broader Implications

If the jet base location is confirmed by higher-resolution follow-up, the implications extend across several domains of astrophysics:

AGN feedback models. Cosmological simulations of galaxy formation rely on prescriptions for how black hole jets deposit energy into the surrounding medium [7][8]. Knowing precisely where and how jets launch constrains these prescriptions at their most fundamental level. The energy carried by M87's jet — potentially 10^37 watts — shapes the thermodynamic state of the intracluster medium across tens of kiloparsecs.

Tests of general relativity. The jet launching region sits within a few tens of gravitational radii of the black hole, where spacetime curvature is extreme [12][14]. Detailed observations of jet morphology and variability in this zone can test predictions of general relativity in the strong-field regime, complementing the shadow measurements that have already provided consistency checks.

Black hole spin measurement. If the BZ mechanism is ultimately confirmed as the dominant driver, the jet power becomes a proxy for black hole spin — a quantity that is otherwise extremely difficult to measure [11][12]. This would open a new observational window on how supermassive black holes grow and evolve over cosmic time.

Pulsar timing and gravitational waves. While some press coverage has linked jet physics to pulsar timing arrays and dark matter constraints, these connections remain speculative. The primary near-term application is in refining models of jet formation physics itself [9].

The Gap Between Press Release and Paper

Several media reports described the finding as "pinpointing" or "tracing" the jet to its source, language that suggests a more definitive result than the paper supports [4][10]. The study's own framing — "first hints," "probable position," "early step" — reflects the inherent limitations of closure phase analysis at the available resolution [3][9]. This gap between headline and finding is common in astrophysics reporting and does not diminish the genuine advance; it simply means the story of M87's jet is still being written, one baseline at a time.

The 2021 EHT observation marks the moment when the black hole's shadow and its jet first appeared, however faintly, in the same data stream. Turning that faint signal into a sharp picture is the work that lies ahead.