The first radio detection of a Type 1a supernova, thanks to e-MERLIN

May 2023

SN2020eyj was detected in the radio using e-MERLIN, over 500 days after the initial optical discovery

Supernovae are the result of the deaths of stars - a large explosion rips the star apart. They are responsible for some of the heavier elements we find in the Universe. One of the best studied types of supernova are the Type 1a, which is caused by a white dwarf accreting too much mass and exploding. Because Type 1a supernovae reach the same critical mass before exploding, they have been used for years as standardisable candles in cosmology. However, two competing mechanisms have been argued to be the progenitor systems of Type 1as, either the merger of two white dwarfs, or, one white dwarf accretes mass from a companion normal star. Detecting radio emission from a Type 1a supernova has long been sought after, as it is expected in the case of accretion from a companion star, but not if two white dwarfs merge.

The Type 1a supernova SN 2020eyj exploded in March 2020 and was followed by the optical community. It was realised from late-time optical spectra that SN 2020eyj was a sub-type of Type 1a supernova which showed signs of circumstellar medium interaction and was re-classified as a Type 1a-CSM supernova. Following this discovery, requests were made to e-MERLIN to observe this potentially interesting source, over 500 days from its initial discovery.

e-MERLIN's unique combination of sub-arcsecond resolution and micro Jansky sensitivity enabled the detection of SN 2020eyj, the first ever for any Type 1a supernova. The detection of the radio emission in this source effectively rules out the white dwarf merger scenario for SN 2020eyj. This discovery of late-time radio emission from a Type 1a supernova will guide and shape future studies with the next generation of instruments like the Square Kilometre Array.

Read the Manchester press release here.

Read the full article here.

LeMMINGs V: linking Hubble with e-MERLIN to explore AGN and galaxy evolution

April 2023

Hubble and e-MERLIN prove a matching synergistic pair linking AGN and galaxy evolution in the LeMMINGs survey

The growth and evolution of galaxies is moderated and shaped by the active galactic nucleus (AGN) in the center and star formation in the bulge. The relationship between the mass of the bulge and the central accreting super-massive black hole powering the AGN is well established, with the two growing together. In nearby galaxies it is possible to distinguish the AGN from the bulge as it is usually much brighter in the optical, but this isn't the case for the lowest-luminosity AGN. In addition, other nuclear features like rings and bars can complicate matters, but using high resolution e-MERLIN radio data and Hubble optical data, it is possible to discriminate the AGN from other sources of emission. The resolution of Hubble is comparable to that of e-MERLIN at 1.5 GHz, making the two a perfect match for exploring the effect the AGN has on the bulge and galaxy as a whole, which is one of the goals of the LeMMINGs survey.

The LeMMINGs is an e-MERLIN legacy project to survey 280 nearby galaxies at 1.5 and 5 GHz at milli-arcsecond resolution to isolate the nuclear emission to find low-luminosity AGN and detect supernova remnant shells which can trace star formation. The 1.5 GHz radio survey of the nuclear regions has already been published. In this work, Bil Dullo and the LeMMINGs team analysed data from the Hubble science archive finding data for 173/280 LeMMINGs galaxies. They performed multi-component decompositions of the optical images to measure the influence of the galaxy bulge, disc, AGN, bar, ring, spiral arms, and nuclear star clusters on the overall galaxy profile. This allowed them to accurately understand the contribution from the bulge to the optical galaxy profile, showing that the bulge becomes rounder, more prominent and larger the further along the Hubble sequence from irregulars to elliptical galaxies. When comparing to the radio information, bulge dominance is also linked to brighter radio core luminosities, with the detection fraction of the radio core increasing with the bulge mass too. A follow up work will look more closely at the radio core luminosity and host bulge properties.

Read the full article here.

Read more LeMMINGs articles here.

e-MERLIN goes to NAM 2023

April 2023

Join us in Cardiff for the National Astronomical Meeting 2023.

The e-MERLIN operations team will be going to Cardiff from 3-7 July 2023 for the National Astronomical Meeting. We have an accepted session entitled "e-MERLIN and SKA pathfinders: preparing UK early-career researchers for science with the SKA". Please submit an abstract before the deadline on the 24th April 2023 to be considered for a talk or poster for this session. We will also have a stand for you to meet the team alongside UK ALMA ARC node and UK SKA SRC members. We look forward to seeing you there!

Find out more about NAM 2023 session here.

Finding mini jets in the mini-halo of RXJ1720.1+2638

March 2023

The discovery of sub-kpc-scale jets in RXJ1720.1+2638 complicates the picture of how the diffuse radio emission is produced in this galaxy cluster.

Radio mini-halos are diffuse synchrotron emission found in the centres of some galaxy clusters. They are thought to arise from either aged relativistic electrons being re-accelerated to energies high enough to cause the synchrotron emission, or by relativistic protons interacting with thermal intra-cluster-medium electrons, producing relativistic electrons as part of a decay chain. In the case of RXJ1720.1+2638, there is competing evidence as to which one dominates. Complicating matters is the presence of an active central nucleus which can also cause energy injection into the system.

Using e-MERLIN Yvette Perrott and her team were able to show unequivocally that RXJ1720.1+2638 has sub-kpc-scale radio jets. The e-MERLIN data recover ~60% of the total flux of the central core when compared to lower resolution studies, indicating that the jet may extend out further. These data have further implications for correlations of the mini-halo luminosity and the brightest central galaxy luminosity.

Read the full article here.

Resolving the extra-galactic population of AGN from star formation with e-MERLIN and EVN

March 2023

Studies of the Northern SPARCS field at milli-arcsecond resolution have isolated compact AGN emission from star formation for the first time.

The SKA PAthfinder Radio Continuum Surveys (SPARCS) are a set of astronomical fields that SKA pathfinder telescopes are observing to make sensitive large-area reference surveys in order to decouple star formation (SF) from active galactic nuclei (AGN) in distant galaxies. Such large and deep surveys will enable the study of galaxy evolution and cosmology and will also determine the key science questions that the SKA will answer.

By using e-MERLIN and the EVN together as one instrument, Ann Njeri and her team observed the Northern SPARCS field with a multi-resolution (10-100 milliarcseconds) programme to resolve the compact emission of AGN from the diffuse star formation emission. The combined use of e-MERLIN with the EVN provides the sensitivity to detect the faintest emission, while the resolution detects compact high brightness temperature emission. Using these high spatial resolution (9 pc – 0.3 kpc at 𝑧 ∼ 1.25) data, 11 sources were detected from a targeted sample of 52 known radio sources from previous observations with the eMERLIN, giving a VLBI detection fraction of ∼ 21%. Isolating these high brightness temperature and compact sources improves the ability to isolate the AGN emission from star formation and hence reduce the uncertainties in star formation estimates using the radio band alone.

This SKA-2 like study is the first of its kind for any of the SPARCS reference fields, providing a high spatial dynamic range view (10–100mas) of the high redshift radio source population. These results will inform future SKA observations, in relation to survey/instrument biases, de-coupling AGN and star-formation and addressing key technical verification challenges for SKA pathfinders (and VLBI) such as data processing and source flux density scaling.

Read the full article here.

e-MERLIN witnesses power of SMBHs during rare tidal disruption event

February 2023

e-MERLIN has been involved in a multi-facility campaign to study the jet launched by a supermassive black hole after a wandering star passed too close and was ripped apart.

These events are known as jetted tidal disruption events (TDEs) and are rather rare: this is the fourth jetted TDE found to date. Since February 2022, observations have been made of the TDE AT2022cmc to understand the long term behaviour of this rare event. The e-MERLIN and multi-facility campaign is designed to understand both the jet and its surrounding environment as it propagates out through the host galaxy.

In a paper published in Monthly Notices of the Royal Astronomical Society, Lauren Rhodes (Oxford) and her team demonstrate the importance of high cadence monitoring for studying the evolving radio counterpart. In AT2022cmc, they find evidence of Doppler boosting, where the observed radiation is boosted as a result of the material moving at relativistic velocities. The observations show that the jet is pointed directly at Earth. The highly relativistic velocities of jets such as that associated with AT2022cmc, means that observers are only able to see those pointed at Earth, and therefore are rarely given such a perfect opportunity to study the jet over the coming years as it decelerates and interacts with the environment of their host galaxy.

Read the full article here.

e-MERLIN Cycle 15 results announcement

January 2023

The e-MERLIN Cycle 15 call for proposals list of accepted proposals is below. The next call for proposals is anticipated in Spring 2023.

PI Title
Engels High fidelity mapping of the OH maser shell of OH39.7+1.5
Giroletti The e-MERLIN view of the radio counterpart of GW events during O4
Johnston Using variability to deconstruct accretion in jet systems around forming massive stars
Kirsten Localising repeating FRBs with EVN-light -- including eMERLIN
Moldon Characterizing the physical properties of the first SN Ia CSM radio detection
Muxlow Does M82 Remnant 41.95+57.5 Harbour an Emerging Pulsar Wind Nebula?
Perez-Torres e-MERLIN radio follow-up of Tidal Disruption Events
Radcliffe A new window on radio AGN with e-MERLIN, EVN and LOFAR
Rhodes Late time observations of GRB 221009A: the brightest radio afterglow to date
Richards Investigating the fine details of dust-forming outflows from evolved stars with water masers
Sarbadhicary e-MERLIN observations of the first JWST-detected supernova remnants in M33
Shu Witnessing the fast jet ejections towards the end of an AGN state transition
Walker Honing in on the homes of repeating FRBs
Yang Detecting an early hint for neutron-star merger jets

Building the RADIOBLOCKS of Next Generation Radio Astronomy

December 2022

RADIOBLOCKS, a new €10m EC funded technical project, will turbocharge the world’s radio astronomy life-cycle, from the telescopes themselves through state-of-the-art receiver enhancements, to intelligent data processing, radio interference management, sophisticated correlators and imaging methods, to expedite the next major astronomical discoveries.

Launching in spring 2023, the 4 year groundbreaking Horizon Europe project, coordinated by Europe’s JIVE-ERIC institute, will pool the expertise from 9 European countries plus Japan, Republic of Korea, South Africa, and the United Kingdom, in a public private partnership, generating cutting-edge frontend technologies, including; multipixel PAF receivers (cm/mm), real-time GPU based correlators and novel RFI detecting data processors. These best ‘bang-per-buck’ modular blocks of technology will be used across multiple radio astronomy facilities, producing cutting edge science representing exceptional value for money.

The Jodrell Bank Centre for Astrophysics and e-MERLIN personnel are playing significant roles in all project parts, including advanced data workflows suitable for large wide-band telescope data volumes - particularly relevant given e-MERLIN’s status as an Square Km Array pathfinder instrument. As Prof Rob Beswick, the project lead at The University of Manchester commented, “The project brings together leading academic research and industry experts from across the world to co-develop new technologies”, whilst Dr. Francisco Colomer, Director of JIV-ERIC and project coordinator stated “For the first time, all will work together to develop the technologies that are necessary for the future evolution of their facilities. This is a paradigm shift”.

Read the full article here.

LeMMINGs : the e-MERLIN view on super-massive black holes in our Galactic back yard

December 2021

The Legacy e-MERLIN programme studying nearby galaxy star formation and super-massive black holes has it's third data release.

All massive galaxies in the Universe host supermassive black holes in their centres, with masses equivalent from million to billion times the mass of the Sun. Some of these black holes gorge on the gas and dust surrounding them at frenetic rates, giving rise to extraordinary physical phenomena including powerful radio jets. However, the vast majority of supermassive black holes are much less ravenous, accreting at rather low rates. The moderate activity of these black holes produces faint emission, which make them hard to find and isolate. Thanks to the recent large-area and deep surveys with new-generation facilities the astronomers are starting to detect this population of low-power active black holes, mostly in the local Universe.

LeMMINGs, one of e-MERLIN’s legacy programmes is probing this population of low-power active galaxies to produce the deepest high angular resolution view of the local Universe in the radio band. The new study, based on this survey and led by Ranieri Diego Baldi, researcher at the Institute of Radio Astronomy (INAF-IRA) in Bologna (Italy), has provided a better understanding of the connection between several physical mechanisms of radio emission and the black-hole accretion mode at the centre of these galaxies.

“This survey has unveiled radio nuclei at the centre in around half of our sample of local galaxies, which were previously classified as active or inactive based mostly on optical data” Baldi explains. “For the first time, thanks to the combination of high-resolution radio data from our survey and archival optical data, we could provide more robust diagnostics to separate stellar and black hole-driven radio nuclei and break the degeneracy among all the possible radio-emitting physical processes. The radio-band maps from this survey have angular resolution of 0.2 arcsecond, equivalent to a ten millionth of the lunar diameter. This high resolution enabled us to detect radio emission on very small scales (a few hundreds of light years), offering direct views of black-hole accretion even in dusty environments, and detecting active black hole at accretion rates below those detectable in other wave-bands.”

The large survey size of a wide range of different types of galaxy allowed the team to discover the radio signatures of supermassive black holes and ascertain how powerful they are. Baldi added “We found that galaxies powered by weak accretion discs can launch fast or slow jets. Seyfert galaxies, which are generally classified as radio silent but can instead launch bright radio outflows. Star forming galaxies may also host weakly active black holes able to emanate small radio jets”. These results are only the start of the LeMMINGs project, with further observations expected to produce more results in the coming years. Furthermore, these results represent the springboard for future deeper studies with up-coming facilities, such as SKAO.

Read the full article here.


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