Shining the light on the LINER NGC 4438
March 2026
By using multi-wavelength data including e-MERLIN, new insights on the powering of the central radio lobe of NGC 4438 have been found.
Shining the light on the LINER NGC 4438
March 2026
By using multi-wavelength data including e-MERLIN, new insights on the powering of the central radio lobe of NGC 4438 have been found.
Low-ionisation nuclear emission-line regions (LINERs) are a type of low-luminosity active galactic nuclei (AGN) that are radiatively inefficient. The impact of feedback on their host galaxies is still under investigation. The lack of significant star formation in LINERs, coupled with their proximity, makes them promising candidates for studying AGN feedback, particularly in their innermost regions. Multi-wavelength observations are particularly useful for probing the connection between the inflows and outflows from the AGN. The outflows can be studied in the radio band and using ionised gas tracers such as the Hα line and X-ray observations to better understand the energy and power of the jets on the local environment.
In this work by Marta Puig-Subirà from IAA-CSIC and collaborators, they combined e-MERLIN radio data with VLA, Hα line data from HST (photometry) and MEGARA/GTC (integral field spectroscopy) and X-ray data from Chandra of the LINER NGC 4438 at matched resolutions to extract information about its outflow at scales of ~25pc. The radio observations revealed non‑thermal synchrotron emission in the north‑western lobe of the galaxy, consistent with the presence of a compact radio jet. When compared to the multi-wavelength data, there is a clear overlap between the radio and Hα structures for the north-western lobe, providing evidence that the jet is likely responsible for inflating a bubble of ionised gas. They also showed radio spectral index maps, allowing the separation between the nucleus (flat spectra) and the outflowing material compatible with non‑thermal synchrotron emission), and measured energy output in the radio jet, which is three orders of magnitude more powerful than the power of the outflow. These results highlight that in NGC 4438, the jet is inflating a bubble and driving feedback in the central region of the galaxy.
The work on NGC4438 is part of a pilot study, which will soon be extended to a larger population of LINERs with a significant presence of ionised gas in the central kiloparsec according to X-ray and optical criteria. Data from e-MERLIN at the L band have been obtained for the entire sample of 30 LINERs, either through proprietary proposals or as part of the LeMMINGs e-MERLIN legacy survey. By comparing with VLA C- and X-band data, this homogeneous dataset, from 1.25 to 12 GHz at sub-arcsecond resolution, will enable a systematic study of the impact of radio-mode feedback on low-luminosity AGN and conduct multi-band spectral index analyses. The future study aims to shed light on the intriguing excess of mass outflow rate expected from their bolometric luminosity and determine how common jet-driven scenario is.
Read the full article here (Puig-Subirà et al. 2026).
Join a plethora of other SKA Pathfinder scientists including e-MERLIN at NAM 2026 in Birmingham.
We are happy to announce a parallel session entitled “Early Career Researchers in Radio Astronomy and the SKAO” will be held at NAM 2026 hosted at University of Birmingham on 7-11 July. The NAM organisers are currently accepting abstracts with the deadline of 2nd April 2026.
The field of radio astronomy will soon be revolutionised by the arrival of the Square Kilometre Array telescopes. Now that the first fringes have been recorded with SKA-Low, and the first SKA-Mid dish is in place, it is time to look to the future of radio astronomy and the scientific opportunities coming up, and to reflect on the state-of-the-art science with precursor/pathfinder telescopes.
The goal of this session is to showcase the breadth of work conducted with SKA precursor and pathfinder instruments, such as e-MERLIN, MeerKAT and LOFAR across a diverse range of science goals, and to provide an opportunity for discussion and connection over plans for future science with the SKA Observatory (SKAO).
The session will be organised and led by members of the SKAO UK Early Career Researcher (ECR) committee, and will build on the success of the equivalent session at NAM2024 and NAM2025.
The latest publication in the LeMMINGs survey has revealed the faintest sub-kpc-scale radio jets and cores from nearby super-massive black holes for the first time.
Understanding the faintest active galactic nuclei (AGN) is essential for building a complete picture of black‑hole growth in the nearby Universe. Low‑luminosity AGN (LLAGN) represent the dominant mode of black‑hole activity today, powered by weak accretion flows that are difficult to detect at most wavelengths. Their subtle radio signatures, often only emitting at sub-mJy-levels, provide one of the clearest pathways to studying accretion and jet production at the lowest luminosities. Because these nuclei are common and span all galaxy types—from ellipticals to late‑type spirals—they offer an unparalleled laboratory for probing the duty cycle of black‑hole activity, the link between accretion and feedback, and how supermassive black holes behave in quiescent, everyday galaxies.
The Legacy e‑MERLIN Multi-band Imaging of Nearby Galaxies survey (LeMMINGs) is designed precisely to answer these questions. Its earlier L‑band (1.5 GHz) campaigns (Baldi et al. 2018; 2021a; 2021b) provided the first sensitive, statistically complete census of compact radio nuclei in the Palomar galaxy sample, uncovering a significant population of LLAGN that had previously gone undetected. However, the complex mixture of star‑formation and AGN emission at L‑band leaves some ambiguity in the physical interpretation. David Williams-Baldwin and the LeMMINGs consortium have now published the C‑band (5 GHz) observations with higher angular resolution (50 mas), reducing the contamination from large‑scale star-forming structures and isolating the true nuclear cores and jet bases.
The new C‑band images reveal compact radio emission in 68 of the 280 nearby galaxies surveyed, corresponding to a detection rate of 24%. The 5-sigma median detection threshold is 0.33 mJy/beam, three times lower than previous radio observations of the same sample. Most detected nuclei (78%) appear as compact, unresolved sources on scales smaller than ~10 pc, while the remaining galaxies display extended jet‑like structures reaching up to several hundred parsecs. The luminosities span an impressive range from 10³⁵ to nearly 10⁴²ergs⁻¹, and the brightest sources are preferentially found in optically classified LINERs and Seyferts—systems already known to host accreting black holes. Crucially, the C‑band observations filter out diffuse star‑formation emission that is present in the L‑band maps, allowing the nuclear component to be cleanly extracted. This confirms that a substantial fraction of LLAGN exhibit compact, high-brightness‑temperature cores consistent with synchrotron jet activity.
The improved spatial resolution also offers valuable constraints on the nature of nuclear activity in galaxies previously labelled as “inactive.” Even among HII and absorption‑line systems, 8% show compact C‑band detections, strengthening the idea that weakly accreting black holes may be far more common than previously thought. As expected, comparisons with earlier 1.5 GHz data reveal that many sources become more compact at 5 GHz, suggesting that the C‑band emission traces the innermost jet regions rather than extended relic structures. However, there were some notable cases where the L and C band positions were offset from the gaia positions, possibly due to misidentification of the nucleus in either the previous L-band maps, or contamination from non-AGN in the gaia catalogue. The L-band and C‑band imaging provides the most definitive radio evidence yet that a notable fraction — perhaps up to 30% — of local galaxies host a radio‑active nucleus.
The new C‑band results mark a step forward for our understanding of nearby black‑hole activity. By tightly isolating the nuclear regions, a "clean" dataset of nuclear core activity is now available, which will enable future work using matched‑resolution L‑ and C‑band imaging to measure robust spectral indices—key for distinguishing AGN, star‑formation, and potential hybrid systems. These data will also feed directly into refined calibrations of the fundamental plane of black‑hole activity, linking radio luminosity, X‑ray luminosity, and black‑hole mass across the full range of accreting systems.
The call aims to support research visits to European institutes that provide direct training and expert guidance in multi-messenger astronomy.
Visits to EU-institutes can be funded through the third ACME trans-national access call, with the deadline for proposals on 2nd April 2026, and 1700CET. These visits are aimed at providing training on a wide range of domains, including gravitational waves, neutrinos, cosmic rays, and photons across the entire electromagnetic spectrum, from very-high-energy gamma rays to X-rays, UV, optical, near-infrared, and radio bands.
To apply for this fund, go to the relevant ACME webpage..
From 14-19 September 2026, scientists from across Europe will be joining us for the biennial meeting of the European VLBI Network Symposium and User's Meeting.
The EVN Symposium happens every two years, bringing together experts from across the world to discuss VLBI and radio astronomy. You can read about previous symposia here.It moves to different venues for every iteration and in September this year, the EVN Symposium is coming to Manchester. Supported by e-MERLIN and run by members of the e-MERLIN support team, we look forward to welcoming users from across the world. The 17th EVN meeting will be the third time it has been held at Manchester/Jodrell Bank, the only place to have held it more than twice!
We plan to have a wide-array of activities, including the usual football match (and possibly some additional sports!), a visit to the Jodrell Bank Observatory and we will include a welcome reception and conference dinner too. We look forward to seeing many colleagues at the meeting!
The EVN Symposium web page is live now and can be accessed by clicking here. You can also submit an abstract and register here.
Members of the e-MERLIN support team recently travelled to L'Aquila, Italy to discuss and develop the EU-funded ACME project.
Last week, members of the e-MERLIN operations support team travelled to L'Aquila in Italy for the combined meeting of Work Package 2 and 3 of the Astrophysics Centre for Multi-messenger studies in Europe, known as "ACME". The goal of ACME is to enhance access for astronomers across Europe to world-class expertise, support and training. In recent months, ACME has been developing hands-on sessions, to facilitate expertise exchange of a wide-variety of astrophysics code bases, as well as providing a dedicatedonline help desk to provide virtual access to expertise and support.
The meeting in L'Aquila was designed to bring members of Work Package 2 and 3 together, which are responsible for widening access to telescope and observatories across Europe by supporting "Open Skies" calls for proposals (WP2) and providing training through trans-national access visits to expertise and virtual access through "Joint Centres of Excellence" across the EU (WP3). In this meeting, we discussed the success of the trans-national access programme and how to support further virtual access through the ACME webpages and support tools.
The new result makes FRB 20190417A the fourth well‑established system with a persistent radio source
Fast Radio Bursts (FRBs) are millisecond‑long, extraordinarily bright flashes of radio waves originating in distant galaxies. Most are seen only once, but a small fraction repeat, enabling detailed follow‑up to probe their environments and host galaxies. The EVN‑Lite PRECISE project — Pinpointing REpeating CHIME Sources with EVN dishes — uses very long baseline interferometry to localise repeating FRBs to milliarcsecond precision, revealing where they sit within their hosts and whether they are linked to compact, steady radio emitters. To date, only a handful of repeaters are confirmed to be associated with such persistent radio sources (PRSs); the new result makes FRB 20190417A the fourth well‑established system in this class.
In a study led by Alexandra Moroianu and collaborators, the signals from EVN and e-MERLIN telescopes were combined and processed them at JIVE to localise multiple bursts from FRB 20190417A with milliarcsecond accuracy, directly demonstrating that the bursts are spatially coincident with a compact PRS. The localisation pins the source to a low‑metallicity, star‑forming dwarf galaxy at z = 0.12817, and visibility‑domain model‑fitting constrains the PRS to a transverse size < 23 pc (≈ < 80 light‑years) with an integrated flux density of ~190 μJy at 1.4 GHz. The team also measured an extreme, time‑variable rotation measure (RM)—ranging from ~3960 to ~5060 rad m⁻² over ~50 days—and place a conservative lower limit on the host’s dispersion measure contribution of ≥ 1228 pc cm⁻³, the largest known so far, pointing to a dense, highly magneto‑ionic local environment.
This precise association strengthens the emerging picture of a rare subclass of repeating FRBs with luminous PRS counterparts, large/variable RMs, and above‑average host DMs. These properties are consistent with scenarios involving very young magnetars powering a nebula, but alternative models—such as hyper‑nebulae or compact objects embedded near massive stars or black holes—remain viable. With PRECISE and broader EVN capabilities, continued milliarcsecond localisations will determine whether PRSs represent a short‑lived phase common to many repeaters or a distinct FRB engine, and will provide targets for deeper, multi‑wavelength study.
New e‑MERLIN observations reveal compact non‑thermal radio emission from a tight pair of low‑mass stars
Low‑mass stars and brown dwarfs dominate the stellar population of the Milky Way, yet their magnetic behaviour remains one of the most intriguing open questions in stellar astrophysics. M dwarfs in particular host intense magnetic fields capable of powering flares, auroral activity, and persistent radio emission. Understanding how these objects generate and sustain such activity is essential for probing the physics of stellar dynamos and the environments of the many exoplanets that orbit these cool stars.
Using a combination of archival VLA data and new high‑resolution e‑MERLIN observations, Kelvin Wandia et al. have detected quiescent radio emission from the nearby tight M‑dwarf binary 2MASS J02132062+3648506 AB. The system is detected at 4–8 GHz with a peak flux density of 356 μJy/beam and a negative spectral index, consistent with gyrosynchrotron emission from energetic electrons trapped in magnetic fields. Strong circular polarisation (~45%) confirms the non‑thermal origin of the emission. The emitting region was constrained to <1.54 Solar radii and an upper limit of ~175 G was placed on the magnetic field strength. Neither the wide T3 brown‑dwarf companion nor the active L5 dwarf 2MASS J0418+2131 were detected, allowing the team to set new, deeper limits on radio emission from these cool objects.
These results demonstrate the power of combining VLA sensitivity with e‑MERLIN’s high angular resolution to probe magnetic activity in the lowest‑mass stars. Future multi‑epoch observations will test whether the system exhibits variability or coherent bursts, while broader surveys will help determine how common such radio‑active M‑dwarf binaries are. As e‑MERLIN continues to expand its coverage of nearby low‑mass stars and brown dwarfs, it will play a key role in building a complete picture of magnetic activity across the bottom of the main sequence.
The new analysis of the gravitational lens JVAS B1938+666 poses questions for theories of cold and warm dark matter.
A mysterious million‑solar‑mass dark object whose internal structure appears unlike anything previously observed has been identified in the grativitational lens system B1938+666, (you can read the previous e-MERLIN news item and associated press releases on this system here.) . First detected through the minute gravitational distortions it imprints on a strongly lensed radio jet, the object has now been examined in unprecedented detail using global VLBI observations including telescopes from Jodrell Bank.
To probe the object’s structure, the team led by Simona Vegetti combined data from the GBT, VLBA and the EVN, forming an Earth‑sized interferometric array capable of resolving the tiny lensing signatures produced by such a low‑mass system. Their modelling reveals that the central region contains roughly a quarter of the object’s total mass, while the outer regions flatten into an extended disk, a configuration not seen in known galaxies or dark‑matter dominated systems. The result challenges expectations from standard cold dark matter theory, which predicts that starless dark‑matter clumps of this mass should be far less centrally concentrated.
This is the third object of its kind identified through gravitational imaging, but the smallest and most precisely characterised to date. All three detections show properties that sit uncomfortably within current dark‑matter models, raising the possibility that they may represent a new class of compact dark systems or point toward physics beyond the standard framework. With new wide‑field surveys and increasingly sensitive high‑resolution radio follow‑up, astronomers expect many more such objects to be uncovered, offering a powerful new window into the unseen structure of the Universe.
The e-MERLIN Time Allocation Group met on 9th December 2025 to consider proposals for Cycle-21. Proposals were received for L-Band (1.3-1.7 GHz), C-Band (4.5-7.5 GHz) and K-band (17-21 GHz). The amount of time approved is set by existing programme observation requirements, scheduling and engineering constraints, and by EVN commitments within the Cycle-21 period. However the amount of available observing time in Cycle 21 has been reduced due to test requirements associated with planned e-MERLIN technical developments.
The e-MERLIN Cycle 21 call for proposals list of accepted proposals is below (in no particular order). The next call for proposals is anticipated in Spring 2026.
The first evidence of co-precession of a black hole accretion disk and jet for TDE has been discovered.
A tidal disruption event (TDE) occurs when a star approaches a supermassive black hole at the center of a galaxy and is torn apart by tidal forces. Some of the stellar material falls back to form a hot accretion disk, releasing intense radiation. TDEs are important windows for studying the activation of quiescent black holes and the formation of relativistic jets. An international research team, studying a TDE named AT2020afhd led by Yanan Wang, has found the most compelling evidence of co-precession between a black hole’s accretion disk and its jet over time.
At approximately 120 million light-years from Earth, AT2020afhd was discovered in January 2024 by an optical survey due to a significant re-brightening and was later confirmed as a TDE. The research team quickly organized an international coordinated observation campaign, including e-MERLIN, mobilizing multiple space- and ground-based telescopes for over a year of high-cadence, multi-wavelength monitoring. X-ray, radio and optical telescopes all participated, achieving full-wavelength coverage of the event.
After analyzing the extensive observational data, the team made a key breakthrough: approximately 215 days after the event, the X-ray light curve exhibited a pronounced quasi-periodic oscillation with a period of about 19.6 days and an amplitude more than 10-fold increase in flux. The radio band also showed strong short-term variability exceeding a 4-fold amplitude, highly synchronized with the X-ray variations. All of this is indicative of a precessing jet and accretion disk.
The disk-jet co-precession observed in certain black hole systems is likely driven by the Lense-Thirring effect, a frame-dragging phenomenon predicted by Einstein’s general relativity. In this effect, a spinning black hole drags the surrounding spacetime, causing an inclined accretion disk and its perpendicular jet to undergo precession. While this phenomenon has been long predicted by theoretical studies and simulations, obtaining direct observational evidence has proven extremely challenging. To address this, the team conducted continuous monitoring over the course of more than a year. Building on these observations, they developed a model of disk-jet coordinated precession that successfully reproduces the observed X-ray and radio variability, providing stringent constraints on the system’s geometric configuration, black hole spin, and jet velocity.
A suite of international arrays including e-MERLIN have found a second radio bump more than 6 years after the initial source detection.
While dozens of tidal disruption events (TDEs) have been identified, that occur when a strayed star approaches too close to a massive black hole and is torn apart by black hole’s gravitational force, only a few are known to produce relativistic jets. Recent observations have suggested that delayed brightening of radio emission appears ubiquitous among TDEs, whose physical origins are still in dispute.
In a recent work by Yang et al. (2025), a team of astronomers has discovered the long-sustained rising radio emission from a TDE occurring in a dwarf galaxy, using a suite of radio telescopes including e-MERLIN. The TDE, designated AT2018cqh, was initially detected by the Zwicky Transient Facility at optical in June 2018 and the eROSITA at X-ray wavelengths in November 2019. In addition to the continuous rise in the radio emission up to ~2510 days since its discovery, the observations found repeating bump features in the light curve, which is unprecedented among known TDEs. The radio spectral evolution is also peculiar, characterized by a shift toward higher peak frequency and peak flux density with time, as evidenced by the quasi-simultaneous e-MERLIN and VLBA observations. This is in contrast to the radio evolution behaviours observed in any other TDEs. The joint observations revealed extreme compactness of the radio emission, unresolved at a scale of <0.2 pc. The team’s analysis, combined with the hydrodynamic simulations, suggests that the extraordinary radio evolution could result from the interaction of outflows launched by TDE with the sub-pc dense clouds surrounding black hole, offering new insights into the origins of delayed fast-rising radio emission observed in some TDEs.
A thermal electron population has been identified in a jetted transient for the first time using radio and sub-mm observations of the tidal disruption event.
Relativistic tidal disruption events (TDEs) are rare, luminous, multi-wavelength transients that occur when a relativistic outflow is launched from a supermassive black hole during the disruption of a star. To date there are only handful of confirmed relativistic TDEs and only two that have been studied in detail. As a result, there are many unanswered questions ranging from focusing on the events themselves: ‘why do only some TDEs launch jets?’ or ‘what are the properties of the TDE jets?’, to much larger scale questions like ‘what is the connection between TDEs and AGN?’.
In a recent work by Rhodes et al (2025), radio and sub-mm observations from a suite of facilities, including e-MERLIN were combined to study the newest relativistic TDE AT2022cmc. Comparisons to the best-studied relativistic TDE, Swift J1644, showed that the light curve evolution was similar in both cases, but AT2022cmc was twice as energetic despite Swift J1644 being systematically more luminous (see Figure 1).
The observations found that the broadband emission is not consistent with only non-thermal synchrotron radiation as is expected from relativistic jets like those associated with gamma-ray bursts. Instead, there is evidence for both thermal and non-thermal electron populations, providing a new insight into the particle acceleration process in jets. The authors find that the Lorentz factor of the jet sits in a region of parameter space higher than those from X-ray binaries and lower than those from gamma-ray bursts, neither of which show evidence of thermal electrons, potentially providing a new avenue for understanding how the radio emission from jets varies as a function of outflow velocity (see Figure 2).
The new Opticon RadioNet Pilot proposal tool developed at Jodrell Bank is now ready for use for the Cycle 21 e-MERLIN Call for proposals!
As part of Cycle 21 of the e-MERLIN call for proposals, software developers at Jodrell Bank have created a new proposal software tool designed to replace the current NorthStar proposal tool. The new tool, named Polaris, was developed as part of the Opticon RadioNET Pilot (ORP), an EU Horizon 2020 project to facilitate collaboration between existing optical and radio astronomy groups across Europe.
To help support users transition to using the new tool, we will be running a Polaris online webinar on Wednesday 12th November 2025 at 1300 GMT. Please get in contact with the e-MERLIN support team for details on how to join this webinar. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101004719.
e-MERLIN observations of the outburst of MAXI J1820+070 have informed relativistic hydrodynamic simulations of X-ray binary jets and their evolution
X-ray binaries (XRBs) are one of the best laboratories for studying a wide-range of astrophysical phenomena: from the connection between accretion and the ejection of jets, to the resulting shock physics as these jets interact with the interstellar medium (ISM). Importantly, they evolve on humanly-accessible timescales and are found at distances that can resolve these discrete components with VLBI arrays like e-MERLIN. By studying such ejecta, important discoveries can be made that can inform our understanding of the launching of radio jets from active galactic nuclei and gamma ray bursts, as well as how the jets shape their own galaxies or immediate environment. Whilst simulations of XRB jets have already helped to provide information on the steady jets, further study of the discrete ejecta is needed to understand the energy transferred into the ISM and constrain the environments that lead to bright and/or relativistic jets.
In this work by Katie Savard and collaborators, they use e-MERLIN and MeerKAT data of the X-ray binary MAXI J1820+070 during its 2018 outburst (Bright et al. 2020) to inform the initial conditions of the relativistic ejecta (Figure 1). Subsequently, this information is used as priors for a hydrodynamic simulation to obtain physical parameters about the ISM and the ejecta, such as the density and particle acceleration efficiencies, which would otherwise remain unconstrained by the data alone. The Pluto code (Mignone et al 2007b) was used to perform relativistic magnetohydrodynamic simulations of the jets as they evolve and interact with the environment.
The simulations showed that the radio blobs ejected by MAXI J1820+070 must be significantly denser than the surrounding ISM in order to propagate to large distances away from the black hole (Figure 2). The low-density environment is explained by ejecta from previous outburst propagating into the ISM causing a high-pressure low-density cavity. This also naturally provides an explanation for the `bubble-like' cavities seen in other sources. The simulations also reveal the presence of a long-lived reverse shock which causes in-situ particle acceleration.
The output of the simulations was then fed into BLOB-RENDER, a tool created to generate pseudo-radio images which can then be used to model the expected sizes, shapes and fluxes of the ejecta (see Fig 3). By incorporating the uv coverage of the MeerKAT and e-MERLIN arrays, it was possible to simulate the original observations together with a real-sky background. The use of this tool enables more direct understanding and interpretation of the simulations, whilst also providing potential uses for predicting future array capabilities of e-MERLIN and other telescopes.
An international team of astronomers has found a low mass dark object in the distant Universe, not by directly observing any emitted light, but by detecting its tiny gravitational distortion of the light from another distant galaxy. Using a special technique called gravitational imaging, it was possible to 'observe' the invisible dark matter clump by mapping its gravitational lensing effect against the radio-luminous arc.
Gravitational lensing is caused by light from a distant object bending around a massive foreground object like a galaxy, causing the background object to be magnified/distorted in large arcs (Figure 1). The gravitational lens source JVAS B1938+666 is caused by a foreground luminous infrared galaxy at the centre of the ring, resulting in stunning arcs known as an "Einstein ring". By studying and measuring the size and shape of the arcs, it is possible to gain information on both the matter content of the lens, in this case the foreground galaxy, but also the distant background object too. Without the lens, the background object would be too faint to study, which makes gravitational lenses excellent laboratories for understanding the expansion of the Universe and dark matter.
Using an international array including the e-MERLIN telescopes, the team led by Devon Powell and John McKean discovered a low mass dark object in the gravitational lensing system B1938+666 (Figure 1 and 2). By using sophisticated modelling algorithms, the team managed to gravitationally 'image' the object, despite it not being detected at optical, infrared or radio wavelengths. This mysterious object has a mass of about one million times that of our Sun. It is located in a distant region of space, approximately 10 billion light years from Earth, when the Universe was only 6.5 billion years old. It's discovery seems consistent with the current best theory about how galaxies like our own Milky Way formed. This is the lowest mass object to be found using this technique, by a factor of about 100.
The team are now analysing the data further to better understand what the mysterious dark object could be. Further work to look at other parts of the sky to find more examples of such low-mass dark objects using the same technique are also underway. If more of these mysterious objects are found in other parts of the Universe, and if they turn out to be completely devoid of stars, then some theories of dark matter may be ruled out.
e-MERLIN has joined the PRECISE project once again to locate a FRB to milliarsecond precision.
An important way to study fast radio bursts (FRBs) is to determine from what type of galaxies they originate and what their local properties are. Fast radio bursts (FRBs) are extragalactic radio flashes of unknown origin(s). They typically last on the order of a millisecond. A small fraction (~3%) of all FRBs have been observed to repeat. The most precise localizations of (repeating) FRBs are achieved with the EVN.
In this work by Mohit Bhardwaj, Mark Snelders and collaborators, the recently detected hyperactive repeating FRB 20240114A (thus detected on 2024 January 14), was localised using the EVN in EVN-Lite mode (PRECISE; Pinpointing REpeating ChIme/FRB Sources with EVN dishes; PI: Franz Kirsten). It is called a hyperactive repeater because thousands of bursts from this source have been found since its discovery using multiple radio telescopes over the world. The observations are done at 1.4 GHz with an ad-hoc sub-array of EVN dishes. For these observations we made use of Effelsberg (Germany), Toruń (Poland), Onsala O8 (Sweden), Westerbork RT-1 (The Netherlands), Noto (Italy), Irbene (Latvia) and six e-MERLIN stations (Cambridge, Darnhall, Defford, Knockin, Pickmere, and Jodrell Bank Mark II; United Kingdom).
The FRB was localised to low-metallicity star-forming dwarf galaxy at a redshift of z = 0.130287. The host was found to be gravitationally bound to a more massive nearby (85 kpc) galaxy at the same redshift. These results expand the known diversity of FRB host environments and offers important insights for interpreting seemingly 'hostless' or highly offset FRBs. Hopefully, future space-based optical/infrared observations (e.g., with Hubble or James Webb Space Telescopes) will reveal the local environment of this FRB source and will fully leverage our precise radio localization.
The e-MERLIN Time Allocation Group met on 3rd July 2025 to consider proposals for Cycle-20. Proposals were received for L-Band (1.3-1.7 GHz) and C-Band (4.5-7.5GHz). The amount of time approved is set by existing programme observation requirements, scheduling and engineering constraints, and by EVN commitments within the Cycle-20 period. However the amount of available observing time in Cycle 20 has been reduced due to test requirements associated with planned e-MERLIN technical developments.
The e-MERLIN Cycle 20 call for proposals list of accepted proposals is below (in no particular order). The next call for proposals is anticipated in Autumn 2025.
South Africa’s MeerKAT radio telescope has successfully conducted very long baseline interferometry (VLBI) observations with telescopes of the European VLBI Network (EVN) — currently the world’s most sensitive VLBI network—which includes the UK’s national VLBI facility, e-MERLIN. Their synergy sets a new standard for global collaboration and significantly enhances both resolution and sensitivity, opening new avenues for scientific exploration.
The collaboration between MeerKAT and the EVN demonstrated, for the first time, how a highly sensitive, modern radio interferometer telescope in the southern hemisphere can significantly enhance the capabilities of existing VLBI networks at centimetre wavelengths. With MeerKAT contributing to the EVN observations, both sensitivity and resolution were considerably improved, as clearly shown in the images below. This is a mutually beneficial partnership with enormous potential for science.
The significance of this collaboration is far-reaching. It paves the way for future international partnerships that could lead to unique scientific discoveries. MeerKAT is the precursor to the mid-frequency array of the Square Kilometre Array Observatory (SKAO) in South Africa, now under construction, which is designed to deliver high-quality data products with exceptional efficiency. This role makes it a crucial pathfinder for future projects and collaborations. MeerKAT’s partnership with the EVN showcases innovative methods for scientific research with this cutting-edge instrument and lays the groundwork for realising SKA-VLBI in the future.
The integration of MeerKAT into the EVN has been prepared through various dedicated tests since 2022-2023. This observation, however, marks the first time MeerKAT has participated in a full, regular EVN observation, in the same way as the other EVN telescopes, including those of the e-MERLIN array. The initial results of this observation, shown in the accompanying images, confirm MeerKAT’s potential as a powerful VLBI station. This represents a significant milestone for science, given the prominent roles of both MeerKAT and the EVN in global astronomical research.
Excited OH and methanol masers have been found to co-exist in 6/10 high mass young stellar objects (HMYSOs) using e-MERLIN observations, probing magnetic fields and physical conditions of the nearby environment.
High-mass young stellar objects (HMYSOs) arise in giant molecular clouds, consisting of a huge amount of gas and dust, which prevents direct observation of the close ambient environment of the forming star at optical frequencies. To track these inner regions, maser emissions in the radio band can be used. The most popular species is the 6.7 GHz methanol maser, which is excited via thermal, infrared dust radiation. The other, less common, 6.035 GHz ex-OH maser is pumped in the same way. But, as current theoretical models show, this maser may arise in the same warm region as the 6.7 GHz transition or may occur in the denser and cooler regions, where the 6.7 GHz transition cannot exist.
The 6.7 GHz methanol and 6.035 GHz ex-OH masers were observed in ten high-mass young stellar objects (HMYSOs) with e-MERLIN by Agnieszka Kobak and collaborators. Among them, eight ex-OH sources were imaged for the first time. Simultaneous observations located the regions of coincidence (or avoidance) of both transitions and showed they are related to local changes in temperatures and/or densities, for scales of a few hundred astronomical units, which are directly associated with the brightness and the distance from HMYSO. The comparison with archival ALMA data shows that coincidence did not relate to kinematic features like discs or outflows. Also, the analysis of evolutionary stage, based on ultra-compact HII counterparts, ratio of 70 micron to 24 micron flux, and ratio of bolometric luminosity to mass, shows that the age of HMYSO did not correlate with coincidence.
The observations were also conducted in full polarization mode to measure the magnetic field for ex-OH masers. The estimation of magnetic field strength gave the typical values from 0.2 to 10.6 mG; for two sources, the reversal of magnetic field direction was observed. The orientations of the magnetic field on the sky-plane seem not to be related to the directions of outflow.
A consistent parsec scale analysis of the nuclear region shows evidence for a corona: a previously unexplained sub-mm excess emission between 200-700 GHz
Previous observations of the nearby radio-quiet Seyfert 2 galaxy showed an unexplained sub-mm excess emission between 200-700 GHz, which was consistent with synchrotron emission from a compact, optically thick corona with approximately 70±5 gravitational radii. This corona contained about 10±2% of its energy density in non-thermal electrons and possessed a magnetic field strength of roughly 148 Gauss, with its spectral energy distribution peaking at approximately 550 GHz. While the corona's luminosity aligned with expectations from mm-X-ray correlations in radio-quiet AGN (though slightly higher), the emission between 10-200 GHz appeared to be dominated by free-free emission rather than coronal processes.
By combining radio to sub-millimetre observations from e-MERLIN, the VLA, and ALMA to study the nucleus of NGC 1068, Isaac Mutie and collaborators have constructed a detailed spectral energy distribution (SED) of the bright, compact region near the galaxy’s central black hole. To perform this work, they matched the data in angular resolution and spatial frequency coverage between 4.5 and 706 GHz, providing a ~100 mas resolution image in each dataset to provide a consistent parsec scale analysis, removing uncertainty on the SED measurements from previous studies. Their findings reveal that the nuclear region is complex, with part of the emission arising from hot, ionised gas via thermal free-free processes, and additional signals originating from a compact corona of high-energy particles, possibly accompanied by synchrotron radiation below 5 GHz. Through careful SED modelling, these combined emission processes successfully reproduce the observed data, including the coronal bump in the 200-700 GHz range, thereby refining our understanding of the interactions between energetic particles in the vicinity of the supermassive black hole and the origin of radio emission in the radio quiet AGN of NGC 1068.
Future observations with e-MERLIN, the VLA, and ALMA, extending this sample to include more nearby radio-quiet galaxies, will be important in understanding the origin of radio emission in such systems by disentangling the contributing mechanisms. Additional high-resolution, low-frequency observations with instruments such as LOFAR and SKA-LOW will also be crucial to constraining the SED at megahertz frequencies.
The elusive intermediate-mass black hole candidate has been detected for the first time in the radio with archival e-MERLIN and EVN data
The nearby starburst galaxy is full of supernova remnants and ultra compact HII regions, which can only be observed in the radio band due to the high optical extinction from the gas and dust in the galaxy. In addition to this population of sources, several exotic radio transients have been discovered in the past, such as SN2008iz, a bright supernova that explode in 2008, or the 'MERLIN' transient that was serendipitously discovered during the follow-up observations the following year. The earliest transient source discovered (Kronberg & Sramek 1985) was found to reside close to the bright X-ray source, M82 X-1: an ultra-luminous X-ray source (ULX) which many observers have suggested is one of the best candidates to be an intermediate-mass black hole (IMBH) due to its X-ray timing properties. IMBHs are of particular interest as they bridge the gap between stellar mass black holes that are often seen in outburst in the Milky Way, and the super-massive black holes observed in the centres of galaxies. Radio emission is theorised to arise from IMBHs, potentially in outbursts similar to those in stellar mass black holes, but relatively little is known about how this radio emission may be generated. As so few IMBHs are known and those that are have poorly constrained black hole masses, M82 X-1 is a useful candidate IMBH source. However, the radio emission of the Kronberg transient was found to not be related to M82 X-1, and as such the search for a radio counterpart to M82 X-1 has continued.
In this work, deep 5-6 GHz observations (r.m.s. sensitivity 7μJy/beam) of M82 obtained in 2015 with the e-MERLIN inteferometer detected a radio source (see image above) 0f 0.15 mJy/beam co-spatial with that of M82 X-1 (see magenta circle in image above, from Xu et al. 2015). Moreover, the source was not detected in radio data at 1.5 GHz obtained a week prior, showing the source to be highly variable on week-long timescales. The rise time of this radio source is consistent with stellar mass black holes and ULXs. Follow up e-MERLIN observations in 2016 also did not detect the source, which aligns closely with the observed X-ray behaviour, suggesting that the source has long term variability and that the radio and X-ray emission may be correlated. Further EVN+e-MERLIN data obtained in 2021 showed a fainter source of 0.05 mJy/beam co-incident with M82 X-1 (see black plus symbol in the image above), indicating that observing depth was necessary to detect it.
When compared to other ULXs with radio emission, of which there are only a handful, the radio loudness parameter for M82 X-1 is similar and the radio counterpart to M82 X-1 resides in a similar region on a radio:X-ray correlation plot to other ULXs too. By invoking the fundamental plane of black hole activity, it is possible to calculate a black hole mass of 2650 solar masses, but this value is highly uncertain due to the lack of simultaneous radio and X-ray data. However, this mass is consistent with the values in the literature, which all point to M82 X-1 being an intermediate mass black hole. This work shows that regular deep radio monitoring of nearby galaxies with high star formation rates and optical or X-ray transients can provide radio detections of these exotic transients, further elucidating the emission processes that are responsible for intermediate mass black holes.
A new synoptic survey mode for EVN+e-MERLIN observations will revolutionise statistical studies of the VLBI sky
The centers of many nearby galaxies are powered by a weakly accreting super-massive black hole (SMBH), known as a "low-luminosity active galactic nucleus" (LLAGN). Unlike their more luminous quasar cousins, LLAGN are not merely low luminosity analogues. Instead, the accretion flow may turn into an advection dominated accretion flow, leading to a different fueling of the central SMBH and thus different observational characteristics. Previously, optical emission line ratios have been used to separate sources where photoionsation in the nucleus is too large to be from star formation alone, and these sources are known as Seyferts. An intermediate case are the low-ionisation nuclear emission line regions (LINERs) which may be powered by a LLAGN and/or star formation. Finally, the HII galaxies show no clear photoionisation consistent with an accreting SMBH, however this doesn't preclude a very weakly accretion SMBH. X-ray emission can also be used to find an accreting SMBH but nuclear absorption can make it difficult to detect their presence. Perhaps the 'gold standard' to detect an LLAGN is a high brightness temperature (TB > 107K) compact radio core with, occasionally, resolved radio jets. To achieve this goal, e-MERLIN and EVN/VLBA are required to search for the jets and the high brightness temperature cores in the nuclear regions of nearby galaxies, helped by the gaia positions of the optical core.
To study the accretion process as a whole, a large statistically complete sample is required. The Legacy e-MERLIN Multi-band Imaging of Nearby Galaxies survey (LeMMINGs) provides such an opportunity: a statistically-complete sample of nearby galaxies with high quality optical spectra and multi-wavelength data. Using the preliminary 5 GHz LeMMINGs results, Xiaopeng Cheng and collaborators searched the VLBA and EVN archives for observations of these sources. Out of the sources not observed by the VLBA or EVN, 36 had flux densities of >1mJy amongst the sources with likely AGN activity, and >3mJy for the HII galaxies where an AGN is less likely. Of the 36 sources, 23 three were detected, with the majority coming from the sources with known LLAGN activity like Seyferts and LINERs, but 3/8 HII galaxies were also detected. This included NGC 2146 which showed a compact radio core with a high brightness temperature and two components either side, the characteristic morphology of a LLAGN.
The new sample has nearly doubled the number of VLBI-detected sources of the LeMMINGs sample. The source compactness was investigated and showed that most sources bar NGC 2655 were core-dominated. Using the combined archival and new datasets, various multi-wavelength correlations were shown to follow those found in the LeMMINGs survey, namely a strong correlation between the radio luminosity and black hole mass and also the fundamental plane of black hole activity. But, only a weak correlation was found between the [O III] line luminosity and the radio emission, potentially due to the different scales probed in the two wavelengths. Finally, the ratio of the radio to X-ray luminosities showed that the Seyfert galaxies were similar in origin to radio quiet quasars, whereas the radio emission in the other LLAGN classes were more consistent with being dominated by a jet.
Using the EVN the parsec-scale cores of some nearby galaxies have been revealed for the first time
SWEEPS (Synoptic Wide-field EVN–e-MERLIN commensal Public Survey) is a proposed commensal survey mode for the EVN+e-MERLIN, where single-target PI-led observations are re-correlated at the position of all known radio sources within 12 arcmin. Initially, the phase centres are selected using the LOFAR Two Metre Sky Survey (LoTSS; Shimwell et al. 2022), in the future however, additional phase centres will be provided by wide-field images using the short baselines of e-MERLIN. Using the integrated EVN+e-MERLIN observations, these wide-field images can be generated on-the-fly during post processing.
This project leverages recent technical advances, such as multiple phase centre correlation and multi-source self-calibration, to bring VLBI into the realm of large statistical studies with ~8000 sources observed per year (Herbé-George et al. in prep.). These will be essential in advancing the key topics studied with VLBI such as, the role of AGN feedback (e.g. Zhuang et al. 2021, King & Pounds 2015), detecting binary black holes to study the hierarchical galaxy formation models (e.g. Rodriguez et al. 2006) and testing different dark matter models with gravitational lenses (e.g. Spingola et al. 2018; Powell et al. 2023)
Here, Célestin Herbé-George and collaborators demonstrator a proof-of-concept of this methodology by detecting a 5.6 mJy core-jet object at 1.7 GHz shown in Figure 1. This object, which was present in the raw visibilities of the observation, would have otherwise been lost from the parent data set and is the first object to be recovered as part of the SWEEPS pilot programme. The other objects present within the primary beams of the EVN+e-MERLIN telescopes are shown in figure 2, and illustrate the potential for increasing sample sizes of VLBI-detected radio sources with commensal observing modes in the near future.
Submit an abstract for the SKA Pathfinders session at NAM!
March 2026
Delving deeper into low-luminosity AGN at 5 GHz with LeMMINGs
March 2026
Proposals open for the 3rd ACME TNA call
March 2026
Register for the EVN Symposium!
February 2026
Widening access with ACME!
February 2026
EVN + e-MERLIN observations localise a repeating fast radio burst to a persistent radio source
February 2026
Radio emission detected from a nearby active M‑dwarf binary
January 2026
A million solar-mass dark object unlike anything seen before discovered
January 2026
e-MERLIN Cycle 21 results announcement
December 2025
Astronomers Reveal a Co-Precessing Black Hole Disk-Jet System
December 2025
Extraordinary rising radio emission after a stellar tidal disruption event in a dwarf galaxy
November 2025
A long-lived radio afterglow in the fifth jetted/relativistic TDE
November 2025
The Polaris proposal tool is now available
October 2025
Simulating BLOBS from e-MERLIN data of X-ray binaries
October 2025
Astronomers ‘image’ a mysterious dark object in the distant Universe
October 2025
A Hyperactive FRB Pinpointed in an SMC-Like Satellite Host Galaxy
September 2025
e-MERLIN Cycle 20 results announcement
July 2025
An Earth-sized radio observatory just got better: South Africa’s MeerKAT telescope joins forces with the European VLBI Network of telescopes
June 2025
Excited for OH in HMYSOs!
June 2025
Coronal emission detected in the nearby archetypal Seyfert galaxy NGC 1068 in radio and sub-mm observations
May 2025
A radio counterpart to the ultra-luminous X-ray source M82 X-1
May 2025
Zooming into the parsec-scale cores of the e-MERLIN legacy sample LeMMINGs with EVN and VLBA
April 2025
SWEEPS: The beginnings of commensal surveys with the eMERLIN–EVN
April 2025
