Research Highlights
Here we show recent research results from the Radio Astronomy/Very-Long-Baseline Interferometry department.
Unveiling the Dusty Veil at the Heart of the Milky Way: New Mid-Infrared Extinction Law
20 December 2025
A new study led by Sebastiano von Fellenberg (affiliated to MPIfR) provides the most detailed look yet at how interstellar dust dims and alters light in the mid-infrared (5–22 µm) toward the very center of our Galaxy — home to the supermassive black hole Sgr A*. Using integral-field spectroscopic data from the JWST’s MIRI/MRS instrument, the team combines dust-emission modeling with hydrogen line diagnostics to derive a refined mid-IR extinction law for the Galactic-center region. This includes evidence for significant spatial variation in extinction over tiny angular scales and confirms the absence of polycyclic aromatic hydrocarbon (PAH) features in the spectra. The new extinction law also enables more accurate correction of infrared observations in this famously dusty environment, improving our ability to measure intrinsic source properties near Sgr A*. The paper appears in the present issue of The Astrophysical Journal, see here.
Rethinking the First Be+Black-Hole Candidate: New Multiwavelength Insights into MWC 656
05 December 2025
A comprehensive new study by Sergio A. Dzib and Frédéric Jaron (both MPIfR) revisits the enigmatic binary star MWC 656, initially proposed as the first Be star with a black-hole companion. By combining deep radio maps from the VLA, precise Gaia astrometry, and Fermi-LAT γ-ray data, the team constrains both the emission mechanisms and the motion of the system. The results reveal a radio–X-ray luminosity ratio consistent with multiple scenarios and show that MWC 656’s motion and location make a runaway origin unlikely. Crucially, the new analysis challenges the black-hole interpretation for the compact object, instead favoring alternatives such as a neutron star or white dwarf. This work refines our understanding of massive binaries and their evolutionary paths. More information, at the original Astronomy & Astrophysics published today here.
Peering into the Brightest Quasars of Cosmic Noon: Unveiling the X-ray Secrets of the Universe’s Most Powerful Black Holes
14 October 2025
Led by the MPIfR PhD candidate Cecilia Degli Agosti, an international research has unveiled new insights into the most powerful quasars shining at Cosmic Noon—the peak epoch of galaxy and black hole growth. In this study, published in Astronomy & Astrophysics, (see original publication here), the team explored the X-ray emission of 85 hyper-luminous quasars from the WISSH project, revealing that their X-ray output varies dramatically despite their uniformly extreme brightness in other wavelengths. This unexpected diversity suggests that the inner accretion regions and energetic coronae of these quasars behave differently from those in less powerful active galaxies. The team also uncovered links between X-ray emission and high-velocity outflows of ionised gas, key signatures of black hole feedback shaping galaxy evolution. These results push the boundaries of our understanding of how supermassive black holes accrete and radiate at the brightest end of the Universe’s history.
Latest on the Symmetric Jets in NGC 1052
19 September 2025
A new study published today in Astronomy & Astrophysics and led by Luca Ricci from the Univ. Würzburg and the MPIfR provides fresh insights into the central regions of the nearby galaxy NGC 1052. Using high-resolution 43 GHz VLBI observations, the team has identified a compact, point-like source within the galaxy’s active nucleus. This discovery suggests that the central engine of NGC 1052 may be powered by a low-luminosity active galactic nucleus (LLAGN), a class of objects that bridge the gap between normal galaxies and the most energetic quasars. Additionally, the study reveals a third spiral arm in the galaxy’s disk, previously undetected, which could provide new clues about its formation and evolution. These findings enhance our understanding of the complex interplay between supermassive black holes and their host galaxies. More, in the original publication here.
ESO Chasing Starlight - New images of M87's black hole show its changing magnetic field
Credit: ESO
Directed by: L. Calçada
Hosted by: S. Randall, Violette Impellizzeri
Written by: S. Randall
Editing: L. Calçada
Videography: A. Tsaousis
Animations & footage: ESO, EHT Collaboration, M. Kornmesser, L. Calçada, N. Risinger, P. Horálek, spaceengine.org, DSS2, ESA/Hubble, RadioAstron, De Gasperin et al., Kim et al., Jean-Pierre Luminet, Weih/Fromm/Younsi/Rezzolla, Smithsonian Astrophysical Observatory
Music: Martin Stuertzer, Envato
Web and technical support: E. Arango, R. Yumi Shida
Scientific consultant: Violette Impellizzeri, Juan Carlos Muñoz Mateos
Acknowledgements: Paul Tiede, Michael Janssen
Promotion: Juan Carlos Muñoz Mateos, O. Sandu
Filming Locations: ESO Supernova (supernova.eso.org)
Produced by ESO, the European Southern Observatory (eso.org)
Selected Media Echo
- Space.com: 'Totally unexpected': Stunning new imagery shows big changes in the 1st black hole ever captured by humanity (photo, video)
- PhysOrg: New images reveal unexpected polarization flips near M87's supermassive black hole
- la Repubblica: Nuove immagini del buco nero M87*, l’astrofisica De Laurentis: "Così lo abbiamo visto cambiare"
- IFLS: Magnetic Flip Seen Around First Photographed Black Hole Pushes "Models To The Limit"
- SciNews: EHT Captures Evolving Polarization Patterns in Messier 87’s Black Hole
- Gizmodo: Something Extremely Strange Is Happening at the Event Horizon of This Supermassive Black Hole
- Futura: Le trou noir géant le plus célèbre de l’Univers a changé de comportement et « met toutes nos théories à l'épreuve » !
- CCTV: M87星系黑洞新图像发布 揭示黑洞附近偏振辐射随时间的演化
- Asia Time: 박종호 경희대 교수 연구팀, 인류 최초 관측 블랙홀 'M87 영상화팀' 참여
Fast Giant Flares in Discs Around Supermassive Black Holes
25 August 2025
Supermassive black holes (SMBHs) are not always quiet cosmic giants—they can suddenly unleash enormous bursts of energy. A new study led by Galina Lipunova (MPIfR) explores how such giant flares can arise from the unstable behavior of matter swirling in accretion discs around SMBHs. The team shows that under certain conditions, a cold, thin disc of gas can rapidly heat up and transition into a hot, turbulent, and geometrically thick state. This dramatic change can trigger outbursts lasting from years to centuries, involving the equivalent of several solar masses of material. The resulting flare can shine as brightly as, or even brighter than, the Eddington limit, with powerful outflows that make the emission highly directional. These findings provide a new theoretical framework for explaining some of the most extreme and long-lasting flares seen in galactic nuclei—events that can resemble tidal disruption flares but are instead driven by the internal physics of accretion discs. Read the publication in Astronomy & Astrophysics
Polarization as a Probe of Neutrino Emission from Blazars
19 August 2025
Where do the most energetic neutrinos in the universe come from? A new study led by Georgios F. Paraschos (MPIfR) provides fresh clues by investigating the blazar PKS 0735+178. During a major flare in late 2021, this blazar was linked to a neutrino event detected by four observatories. Using high-resolution very-long-baseline interferometry (VLBI) images in polarized light, the team uncovered evidence of a shock front propagating through the jet—an engine powerful enough to accelerate protons to extreme energies. The study suggests a coherent scenario where such shocks in blazar jets can give rise to both the observed flare and the necessary conditions for neutrino emission. This finding strengthens the case for blazars as key sources of high-energy neutrinos, opening a new window into the physics of cosmic particle accelerators. Read the publication in The Astrophysical Journal
Ribbons in the Sky: Space Radio Telescope Reveals Jet Twists from a Distant Blazar
30 July 2025
A remarkable new image of the active galaxy OJ 287 reveals a sharply bent, ribbon-like jet of plasma extending from its central supermassive black hole. This high-resolution view, made possible by the combination of a space-borne radio telescope and an international network of ground-based observatories, provides new insights into the nature of relativistic jets and the extreme environments surrounding black holes.
The image was produced using data from the RadioAstron mission, which operated between 2011 and 2019, and utilized a 10-meter space antenna in conjunction with 27 radio telescopes on Earth. Together, these facilities formed an interferometric array exceeding the diameter of Earth, enabling an angular resolution fine enough to distinguish structures separated by just a few light months at the distance of OJ 287—approximately 5 billion light-years away.
The observations revealed an exceptionally narrow and twisted jet structure, with multiple sharp bends appearing close to the galactic nucleus. This discovery sheds new light on the mechanisms responsible for shaping jets and suggests dynamic interactions likely connected to orbital motion near a black hole binary system.
Polarization measurements further revealed that the magnetic field in the jet is tightly aligned with the plasma flow, providing key constraints for jet-launching models. The team also detected the onset of a new shock wave propagating through the jet, which coincided with a burst of high-energy gamma-ray emission observed in early 2017—highlighting a potential link between jet dynamics and high-energy processes.
These results were obtained through the coordinated effort of institutions across several countries and represent a significant technical and scientific achievement in high-resolution radio astronomy. The study has been conducted over more than a decade, beginning in the early 2010s and culminating in detailed imaging from observations made in 2016.
Researchers at our department have played a central role in the success of this project, contributing to the preparation, scheduling, correlation, calibration, and analysis of RadioAstron data throughout the mission’s lifetime. This research is part of the M2FINDERS project, funded by the European Research Council (ERC) under the Horizon 2020 programme (grant agreement No. 101018682).
More information is available at the original publication in A&A, available here.
International press releases report these results, led by Thalia Traianou and with participation of several MPIfR colleagues: I. Myserlis, G.-Y. Zhao, Y.Y. Kovalev, and A.P. Lobanov. See here:
- Instituto de Astrofísica de Andalucía, Granada, Spain: The surprising structure of the jet of a possible binary system of supermassive black holes is revealed
- University of Heidelberg: OJ 287: New Image from the Heart of a Mysterious Galaxy
- Technical University Delft: Ribbons in the sky: Space radio telescope reveals plasma jet in a supermassive black hole binary candidate
Black Hole Imaging Honored
2025 Frontiers of Science Award for the Event Horizon Telescope Collaboration
13 July 2025
The groundbreaking research paper “First M87 Event Horizon Telescope Results IV. Imaging the Central Supermassive Black Hole”, featuring major contributions from the Max Planck Institute for Radio Astronomy (MPIfR), has been awarded the 2025 Frontiers of Science Award in the category “Artificial Intelligence for Physical Sciences.” The award ceremony took place on July 13, 2025, at the China National Convention Center (CNCC) in Beijing.
Presented by the International Congress for Basic Science (ICBS), this prestigious award recognizes scientific work of exceptional quality and lasting significance. For 2025, the ICBS honored outstanding achievements in mathematics, theoretical physics, and theoretical computer and information sciences — spanning both basic and applied research. Among this year’s laureates is the Event Horizon Telescope (EHT) collaboration, whose pioneering imaging of a black hole captivated global attention in April 2019.
Representing the EHT Collaboration at the award ceremony were José Luis Gómez (Instituto de Astrofísica de Andalucía, Granada) and Andrew Chael (Gravity Initiative at Princeton University), who accepted the honor on behalf of the global team.
The celebrated research, published in The Astrophysical Journal Letters in 2019, marked the first time humanity had ever seen a direct image of a black hole. The EHT collaboration, which brought together scientists from around the world, included key researchers from all three departments of the MPIfR. Their results were shared in a coordinated, global announcement that made headlines around the world. Notably, the awarded paper has since been cited over 1,300 times, reflecting its enduring scientific impact (source: Dimensions).
What Did the Paper Show?:
In this study, the Event Horizon Telescope team revealed the very first image of a black hole — the supermassive black hole at the center of the galaxy M87 — using a worldwide network of radio telescopes. The image shows a bright, glowing ring of hot gas surrounding a dark central region, known as the black hole's “shadow,” caused by its immense gravitational pull. The ring’s size and shape matched theoretical predictions, offering a stunning confirmation of Einstein’s theory of general relativity. To make sure the image was scientifically reliable, the researchers used advanced imaging algorithms and ran blind tests with multiple independent teams. Despite varying techniques and parameters, all teams consistently recovered the same ring-like structure, proving the robustness of the result. This iconic image opened a new window into the study of black holes, demonstrating how artificial intelligence can be used to process complex astronomical data and visualize phenomena at the edge of space and time.
You can view the award presentation (minute 4:33:00–4:35:00) at:
🔗 https://www.youtube.com/live/rUHRF6kpX0c?si=9i9YMWDncvwosMth&t=16340
The authors affiliated with the Max Planck Institute for Radio Astronomy (MPIfR) in this publication are: Walter Alef, Rebecca Azulay, Anne Kathrin Baczko, Silke Britzen, Gregory Desvignes, Ralph P. Eatough, Ramesh Karuppusamy, Jae Young Kim, Michael Kramer, Thomas P. Krichbaum, Kuo Liu, Andrei P. Lobanov, Ru Sen Lu, Nicholas R. MacDonald, Karl M. Menten, Cornelia Müller, Aristeidis Noutsos, Eduardo Ros, Helge Rottmann, Alan L. Roy, Tuomas Savolainen, Lijing Shao, Pablo Torne, Jan Wagner, Norbert Wex, Robert Wharton, and J. Anton Zensus.
A Smarter, Faster Way to See the Radio Sky
17 June 2025
How can astronomers process the enormous volumes of data expected from the next generation of radio telescopes—without being overwhelmed by computing costs? A new study led by Hendrik Müller, astronomer affiliated to the MPIfR, addresses this challenge by rethinking a decades-old standard in radio astronomy: the CLEAN algorithm. The team’s work appears in the current issue of Astronomy & Astrophysics, available here. CLEAN is the go-to method for transforming raw interferometric data into the detailed images astronomers use to study the universe. But as telescopes become more powerful and datasets grow larger, CLEAN’s efficiency limits are being tested. In response, the researchers developed Autocorr-CLEAN, a novel variant that intelligently clusters components based on the autocorrelation of residuals—streamlining the deconvolution process without sacrificing accuracy. Autocorr-CLEAN maintains the high fidelity of modern multiscalar methods but operates with a speed closer to the classic CLEAN. It does so by introducing flexible, nonradially symmetric basis functions that adapt dynamically to the residual noise structure—avoiding computational bottlenecks and accelerating convergence. This breakthrough not only speeds up the imaging process by up to an order of magnitude, but also integrates seamlessly into existing data pipelines. As radio observatories prepare for unprecedented data loads, Autocorr-CLEAN may become a cornerstone of future analysis—helping astronomers peer deeper into the cosmos with sharper and faster reconstructions.
Unveiling Black Hole Physics with Deep Learning and the Event Horizon Telescope
06 June 2025
A trilogy of new studies led by Michael Janßen, Radboud University astronomer also affiliated to the MPIfR, showcases how deep learning and Bayesian inference are transforming our understanding of black holes observed with the Event Horizon Telescope (EHT). These three companion papers, published in the current issue of Astronomy & Astrophysics, mark a major step forward in interpreting horizon-scale observations of Sagittarius A* and M87*, by combining cutting-edge simulations, improved data calibration, and advanced machine learning tools.
In the first paper, Deep learning inference with the Event Horizon Telescope: I. Calibration improvements and a comprehensive synthetic data library, the team presents significant enhancements to the EHT’s data calibration pipeline, including improved handling of atmospheric phase fluctuations and polarization information. They also introduce a massive library of 962,000 synthetic EHT datasets derived from state-of-the-art general relativistic magnetohydrodynamic (GRMHD) simulations. These realistic synthetic observations capture the complexity of black hole environments and will serve as the foundation for future parameter inference studies. The work highlights which data features are robust and which are vulnerable to instrumental effects, laying the groundwork for more reliable comparisons between models and observations.
The second paper, Deep learning inference with the Event Horizon Telescope: II. The ZINGULARITY framework for Bayesian artificial neural networks, introduces ZINGULARITY, a new open-source framework for training Bayesian neural networks on EHT data. Designed to handle massive synthetic datasets with high fidelity, ZINGULARITY uses the TensorFlow Probability library and the HOROVOD framework for efficient distributed learning. This marks the first application of deep Bayesian neural networks to EHT data, enabling the extraction of black hole parameters—such as spin and magnetic field configuration—along with trustworthy uncertainty estimates. The study emphasizes that rigorous model complexity and data realism are key to preventing overfitting and ensuring reliable generalization from synthetic to real observations.
In the final installment, Deep learning inference with the Event Horizon Telescope: III. ZINGULARITY results from the 2017 observations and predictions for future array expansions, the team applies their trained ZINGULARITY networks to actual 2017 EHT observations. For M87*, they infer a retrograde, magnetically arrested disk (MAD) accretion flow and a black hole spin between 0.5 and 0.94. For Sgr A*, the analysis points to a high spin (~0.8–0.9), a prograde accretion structure, and a weak jet seen at a moderate inclination. The authors also forecast how future EHT upgrades—especially the addition of the Africa Millimeter Telescope—will significantly sharpen parameter estimates and improve our ability to test general relativity in the strong-field regime. This series exemplifies how interdisciplinary methods are pushing the frontier of black hole astrophysics.
Probing the Magnetic Heart of 3C 111’s Jet
03 June 2025
How is the magnetic field structured inside the powerful jets emerging from active galactic nuclei? In a recent study led by Vieri Bartolini, a PhD candidate at the MPIfR, researchers explored this question using multifrequency, high-resolution observations of the radio galaxy 3C 111. The results are published in the current issue of Astronomy & Astrophysics, available here. By analyzing simultaneous Very Long Baseline Array (VLBA) data from 5 GHz up to 87.6 GHz, the team investigated both the total intensity and polarization structure of the jet, uncovering detailed spectral and magnetic field properties down to sub-parsec scales. Their analysis revealed a frequency-dependent core shift and distinct spectral behavior in the core and extended jet regions—including an unusual flat-spectrum feature approximately 1–2 parsecs from the core. This feature, also associated with a region of high rotation measure, likely corresponds to a dense plasma cloud from the galaxy’s clumpy torus. Further analysis at lower frequencies uncovered a rotation measure gradient across the jet, providing strong observational evidence for a helical magnetic field configuration—consistent with theoretical predictions. These findings not only offer new insight into the magnetic environments surrounding supermassive black holes but also contribute to our broader understanding of relativistic jet formation and evolution.
Fringes at 3.5 mm Wavelength Between APEX and Effelsberg!
23 May 2025
A symbolic moment in millimetre-wave VLBI at the Max-Planck-Institute für Radioastronomie (MPIfR): For the first time, the 12-meter APEX telescope in Chile and the 100-meter Effelsberg radio telescope in Germany have successfully detected VLBI fringes between them.
Both telescopes are operated by the MPIfR). APEX, located at 5100 m altitude on the Chajnantor Plateau in the Chilean Andes, and Effelsberg, nestled in the Eifel mountains, have vastly different designs and operating environments. Effelsberg has been a VLBI station since the mid-1970s; APEX since 2015. Thanks to the completion of N3AR at APEX, both now support a common frequency band.
In April 2026, as part of the Global mm-VLBI Array at 3.5-mm wave, the two telescopes observed the bright quasar 3C273, among other sources. This observation marks a symbolic handshake between both MPIfR telescopes—separated by 9637 km—as they detected the same wave from a distant quasar.
The figure shows the fringe plot confirming this detection. Adding APEX to the GMVA greatly improves the array's north-south resolution, resulting in much more enhanced images of quasars and black hole environments.
This milestone highlights the expansion of mm-wave VLBI capabilities and paves the way for even higher-resolution astronomy in the future.
Exploring the Magnetic Secrets of Blazar Jets
07 May 2025
How are the magnetic fields inside distant, powerful jets of plasma—launched from active galactic nuclei—shaped and structured? In a study led by Joana A. Kramer as part of her PhD work in our scientific department, researchers investigate this question using high-resolution observations of circular polarization in blazar jets. This study is published at the present issue of the journal Astronomy & Astrophysics, see here. By combining deep radio observations with cutting-edge simulations, the team examined the magnetic field signatures in a carefully selected group of nine blazars. The study focuses on how the sign and structure of circular polarization, along with the orientation of the electric vector position angle (EVPA), relate to theoretical predictions of jet magnetism. Their findings reveal compelling patterns: magnetic fields that appear toroidal, helical, or poloidal in nature, depending on frequency and source. This research brings us one step closer to understanding the complex and dynamic physics driving some of the universe’s most energetic phenomena.
Unravelling the Vortex Dynamics in a Cosmic Jet
08 April 2024
What creates the swirling, thread-like structures seen in powerful extragalactic jets? In a new study led by Georgios F. Paraschos from the MPIfR, researchers delve into the heart of the radio galaxy 3C 84 to uncover the physical processes shaping its jet. Using ultra-high-resolution observations from a global very-long-baseline-interferometry (VLBI) campaign, the team identified a striking pattern in the jet’s structure—consistent with a Kelvin-Helmholtz instability, a type of plasma turbulence that occurs when layers of fast-moving material interact. The analysis reveals a jet characterized by multiple instability modes, pointing to a Mach number of about 5 and a relatively low internal sound speed. This work provides compelling evidence that the inner dynamics of the jet may be directly influenced by activity in the galaxy’s accretion disc, offering a clearer picture of how such extreme cosmic outflows evolve. This work is published at the present issue of Astronomy & Astrophysics, see here.
Twisting Magnetic Fields: A Helical Structure Revealed in Quasar NRAO 150
25 March 2025
Quasars are among the most powerful objects in the universe, powered by supermassive black holes and their swirling jets. But what role do magnetic fields play in shaping these jets? In the latest issue of Astronomy & Astrophysics (see here) Jack Livingston and a team from the M2FINDERS project at the Max Planck Institute for Radio Astronomy (MPIfR) unveil a striking new discovery: a helical magnetic field twisting around the jet of quasar NRAO 150. Using high-resolution polarimetric very-long-baseline interferometry (VLBI), the researchers detected clear gradients in Faraday rotation, revealing the signature of a helical+toroidal magnetic field structure. This field appears to be concentrated within the innermost jet, influencing its flow and polarization properties. Such findings provide crucial evidence that magnetic fields play a key role in jet formation and stability, offering new insights into how quasars channel energy across vast cosmic distances.
Hunting for New Jet Launch Sites in Active Galaxies
12 March 2025
How do supermassive black holes launch their powerful, relativistic jets? Until now, detailed imaging of jet formation has been limited to just a few exceptional sources like M87. In the latest issue of Astronomy & Astrophysics (see here) Bia Boccardi, Otto Hahn Group leader at the Max Planck Institute for Radio Astronomy (MPIfR), presents a search for new prime targets to study jet formation up close. Using high-resolution very-long-baseline interferometry (VLBI) at centimeter and millimeter wavelengths, the team examined 16 previously underexplored radio galaxies, spanning a wide range of jet powers and accretion modes. Their results more than doubled the number of sources imaged on the smallest scales, revealing intriguing jet structures—some with limb brightening, others with two-sided symmetry. Among the most promising candidates for future ultra-high-resolution studies are 3C 31, 3C 66B, 3C 465, and 3C 452. These sources are now poised to become key targets for the next generation of telescopes, including the ngEHT and ngVLA, bringing us closer to unraveling the mechanisms behind jet launching in active galaxies.
Is a Hidden Black Hole Warping the Jet of a High-Energy Neutrino Source?
11 March 2025
TXS 0506+056 is no ordinary blazar—it was the first active galactic nucleus linked to a high-energy neutrino, offering a rare glimpse into the cosmic engines that power these elusive particles. In a new study published in Astronomy & Astrophysics (see here) Silke Britzen and a team from the Max Planck Institute for Radio Astronomy (MPIfR) uncover an unexpected twist: the jet and core of TXS 0506+056 may be gravitationally lensed. Using long-term very-long-baseline interferometry (VLBI) data, the researchers found that the jet structure of TXS 0506+056 has undergone dramatic changes over time. Around 2016, coinciding with a major radio flare, the jet components began to arrange themselves in a ring-like structure—a pattern that defies typical blazar jet behavior. This unusual evolution could be explained by gravitational lensing, potentially caused by an unseen supermassive black hole acting as a cosmic magnifier. If confirmed, this discovery would reshape our understanding of both jet physics and the environments in which high-energy neutrinos are born.
X-ray Silence: Shedding Light on the Mysterious Energy Budget of a Hyperactive Fast Radio Burst
10 March 2025
Fast radio bursts (FRBs) are among the most enigmatic cosmic signals, and some—like FRB 20240114A—repeat at a staggering rate. But how much energy do they release beyond the radio spectrum? In the present issue of Astronomy & Astrophysics, Florian Eppel from the University of Würzburg and the Max Planck Institute for Radio Astronomy (MPIfR) presents a pioneering multiwavelength study of this hyperactive FRB, searching for an X-ray counterpart (see publication here). Using the Effelsberg 100-m radio telescope and XMM-Newton, the team observed 459 bursts in a single session. Yet, despite extensive X-ray coverage, no simultaneous high-energy flashes were detected. This non-detection allows for stringent constraints on the X-ray-to-radio fluence ratio, suggesting that FRB 20240114A emits far less X-ray energy than previously seen in magnetar-driven FRB-like bursts. Could this FRB still share a common origin with Galactic magnetars, or does it hint at a different engine? Future multiwavelength campaigns will push these limits further, helping to unravel the power source behind these cosmic signals.
How Blazar OJ 248’s Jet Unleashed a Gamma-Ray Flare
25 February 2025
Blazars are some of the most extreme objects in the universe, capable of launching powerful jets at nearly the speed of light. But what triggers their sudden bursts of high-energy radiation? In the present issue of Astronomy & Astrophysics (see here), G.F. Paraschos from the Max Planck Institute for Radio Astronomy (MPIfR) explores the dramatic γ-ray flare of the blazar OJ 248—the only one ever recorded from this source. Using ultra-high-resolution radio imaging (VLBI), the study reveals that during the flare, the jet’s polarization properties changed in a striking way: the electric vector position angles (EVPAs) rotated, aligning perpendicularly to the jet flow. The most likely culprit? A shockwave crashing through an existing jet structure, triggering a cascade of interactions that up-scatter photons to γ-ray energies. This "shock-shock" scenario offers new insight into how flares are powered in blazars, shedding light on the hidden physics of these cosmic accelerators.
JWST Unveils a Black Hole Flare in Unprecedented Detail
20 January 2025
For the first time, astronomers have detected a flare from our galaxy’s central supermassive black hole, Sgr A*, in the elusive mid-infrared (MIR) range—thanks to NASA’s James Webb Space Telescope (JWST). In a new study published in Astrophysical Journal Letters (see link here), Sebastiano von Fellenberg and colleagues from the Max Planck Institute for Radio Astronomy (MPIfR) report this groundbreaking observation, offering fresh insights into the extreme physics at play near black holes. The flare, lasting about 40 minutes, followed a pattern seen in near-infrared (NIR) and X-ray bursts, with its spectral properties revealing that high-energy electrons cooled rapidly via synchrotron radiation. A follow-up detection at millimeter wavelengths, delayed by about 10 minutes, hints at a dynamic interplay between magnetic fields and particle acceleration. With field strengths of 40–70 G in the emission region, this study provides a crucial missing piece in our understanding of how black holes power their flickering emissions.
Magnetic properties of the jet base in the radio galaxy NGC 315
14 January 2025
This study, led by MPIfR astronomer L. Ricci within the Otto Hahn research group headed by B. Boccardi, investigates the spectral and magnetic properties of the relativistic jet in the nearby radio galaxy NGC 315. Observations reveal a toroidal-dominated magnetic field structure, which influences the jet collimation and acceleration on sub-parsec and parsec scales. A steep radio spectrum at the base of the jet suggests intense synchrotron cooling, transitioning to flatter spectral regions at larger scales. At the jet base, magnetic energy dominates, gradually transitioning to equipartition with particles as the jet expands outwards. A nearly linear increase in magnetic field strength with distance from the core supports theoretical models of jet formation. This research provides critical constraints on the magnetization and geometry of the magnetic fields in relativistic jets, advancing our understanding of jet dynamics in active galactic nuclei. For a detailed discussion, see the original paper here.
