Description
Organisers: Johannes Allotey, Emmy Escott, Catherine Hale, James McGarry, Lucy Oswald, David Williams-Baldwin
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). We also will likely include discussion from invited speakers to update on the SKAO and the Science Regional Centres.
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 NAM2023.
Using the SKAO to map the intensity of neutral hydrogenโs 21cm emission line will be a golden opportunity to constrain models of cosmology. Neutral hydrogen will reside around peaks in the late Universe's underlying density field, the clustering of which is rich in cosmological information. I will present results from MeerKAT pilot surveys where the 64 single-dishes scan the sky in...
The cosmological 21-cm forest, a series of absorption lines in the spectra of high-z radio-loud sources arising from the hyperfine structure of neutral hydrogen residing in the intergalactic medium (IGM), has a potential to be a unique probe of the neutral IGM during the Epoch of Reionization. While there are no detections of this signal up to date, I will argue that the prospects of detecting...
Non-thermal radio filaments (NRFs) were first discovered 40 years ago in the Galactic Centre (GC) with their astrophysical origins still being a topic of debate. The SARAO MeerKAT Galactic Plane Survey (SMPGS) recently revealed a population of NRFs found throughout the Galactic Plane (GP). Confirming these would challenge NRF origin models that rely on the unique environment of the GC and...
Radio Frequency Interference is one of the most detrimental effects for radio astronomy. The SKAO takes the protection of the radio frequency spectrum in both sites very seriously, placing great effort in controlling our own activities, our equipment and the effects that external users of the radio spectrum can produce on our science.
This talk will describe the Spectrum Protection Office...
Red quasars exhibit a higher incidence of compact (galaxy-scale or smaller) radio emission than blue quasars, arising from systems near the radio-loud/radio-quiet threshold. This result cannot be fully explained by the standard orientation model, instead favouring red quasars as a distinct phase in a quasarโs lifecycle, possibly an obscured-to-unobscured transition, where low-power jets and/or...
The unprecedented sensitivity of wide-area, low-frequency radio surveys like the LOFAR Two-Metre Sky Survey (LoTSS) has uncovered a vast population of radio-loud AGN (RLAGN) previously missed by high-flux-density surveys such as the Third Cambridge Catalogue of Radio Sources (3CRR). As a key SKA precursor, LOFAR plays a crucial role in identifying these populations and advancing our...
Thanks to SKAO (Square Killometre Array Observatory) pathfinders, recent technological developments have allowed radio surveys to go deeper than ever before. One such example is the International LOFAR Telescope (ILT). The LOFAR Two-meter Sky Survey (LoTSS) Deep Field first data release provides us with 6โ images at 144 MHz with sensitivities down to 20 ฮผJy/beam using just the Dutch stations....
SKA pathfinders can sample wide swathes of the radio sky with unprecedented sensitivity and cadence. As a result, we are now discovering novel radio transients across an immense range of astrophysical regimes - from flare stars to FRBs. I will discuss recent, serendipitous discoveries being made with the MeerKAT and ASKAP radio telescopes. I will show how unsupervised machine learning...
CLASS B2045+265 is a gravitationally lensed system where a radio-loud background galaxy is lensed by a radio-loud foreground galaxy, producing four lensed images. The flux-ratios of the four lensed images are known from previous observations to be inconsistent with the predictions from a simple singular isothermal ellipsoidal (SIE) model for the foreground mass distribution. This may suggest...
The SKA will identify tens of millions of new sources - but identifying and classifying their morphologies will require novel, robust, reliable, and efficient methods. In particular, complex sources are of significant interest thanks to (e.g.) wide-angled tails being "weather vanes" for galaxy cluster activity, and the possibility of new discovery space for galaxy evolutionary pathways....
The MeerKAT telescope is a precursor for the SKAO, the next generation radio observatory. We have been successful in being awarded observing time on MeerKAT for a pathfinder SKAO-project to conduct a wide-field (approx. half of the whole southern sky) survey, called MeerKLASS. Several hundred hours of data at 580-1015 MHz have already been collected and we exploit a technique called...
Active galactic nuclei (AGN) can have a significant effect on their host galaxies by regulating their growth or suppressing star formation (known as AGN feedback). Of particular importance for massive galaxies and clusters are jet-mode AGN which display powerful radio jets and keep galaxies โred and deadโ once quenched. However, until recently, the cosmic evolution of jet-mode AGN has...
A key component of AGN feedback is the injection of kinetic energy from radio jets. However, thereโs a fundamental lack of understanding of why quasars, otherwise very similar, have such a wide range of radio jet powers and, therefore, the impact of AGN jets. Using large samples from LoTSS DR2 coupled with a Bayesian parametric model, we can separate and quantify the jet and host galaxy...
We present the discovery of a >66 kpc radio jet in the radio-loud quasar J1601+3102, residing at a spectroscopically confirmed redshift of z = 4.912. This makes it the largest projected radio jet known to date at such early times. Using the International LOFAR Telescope, two apparently unrelated "companion sources" have been spatially resolved into two radio lobes. Spectroscopic follow-up with...
Active galactic nuclei (AGN) play a crucial role in the evolution of massive galaxies, but their fueling and feedback efficiency depend on the environment. In this talk, I will present a statistical study of the orientations of AGN jets and their optical counterpart in relation to the cosmic web environment, leveraging data from the Low-Frequency Array (LOFAR). Using LOFAR Two-metre Sky Survey...
Radio activity in low-mass stars, including M dwarfs and substellar objects, has gained significant attention over the past decade. This interest has been driven in part by SKA pathfinder telescopes, particularly LOFAR, which have provided critical insights into the radio properties of stellar/sub-stellar objects at meter wavelengths. The upcoming Square Kilometre Array (SKA) is poised to...
The radial acceleration relation (RAR) is a fundamental relation linking baryonic and dark matter in disc galaxies through the observed acceleration derived from dynamics to the one estimated from the baryonic mass. Notably, this relation exhibits small scatter, thus providing key constraints for models of galaxy formation and evolution, by essentially allowing us to map the distribution of...
We report the largest study to date of the resolved Faraday rotation (RM) and depolarization across the lobes of double radio sources. Our work utilises the ongoing EMU and POSSUM surveys with ASKAP, which will cover half the sky. EMU produces broad-band Stokes I images and a source catalogue at 943 MHz. POSSUM performs RM synthesis on the same data, yielding RMs at each high-SNR...
In the late Universe, neutral hydrogen (HI) is found inside dark matter haloes hosting galaxies. Using a technique called intensity mapping, the distribution of HI can be used as a tracer for large-scale structures. The accessible scales from the data depend on the instrument used, i.e. single dish telescope or interferometer. Radio interferometers are sensitive to scales that simultaneously...
Recently, the ASKAP POSSUM and MeerKAT surveys revealed an apparent lack of radio source counts in the Fornax galaxy cluster field. The sources in this patch of sky also appeared to be less polarised. These observations are peculiar and could be important signatures of depolarisation on galaxy cluster scales. In this work, we quantified the effects on polarisation of radio point sources behind...
Giant pulses (GPs) are short bursts of highly energetic and significantly polarized radio emission, observed in a handful of pulsars. Competing theories suggest GPs originate from vacuum gaps near the neutron star surface, or alternatively near the outskirts of the pulsar magnetosphere. Agnostic to our prescription for what is causing the GP emission, observations suggest GPs and regular...
Source extraction in extragalactic HI radio surveys has traditionally made extensive use of visual, by-eye inspection. Efforts to quantify its completeness and reliability have, however, been limited by the often-laborious nature of the procedure. The result is that there are many unanswered questions and persistent misconceptions : is visual source finding really totally subjective, or can...
The redshifted 21-cm signal from Cosmic Dawn (CD) and the Epoch of Reionization (EoR) is challenging to observe due to a variety of systematic effects that radio interferometers must contend with. The modulated foreground, which is notoriously difficult to model; substantial gaps caused by the excision of regions necessary due to radio frequency interference (RFI); and artifacts resulting from...
In this presentation, we detail a search conducted on WiggleZ galaxies cross-matched with bright ASKAP-FLASH sources for associated and intervening 21 cm absorption. HI has historically been difficult to probe at 0.4 < $z$ < 1.0 due to the faintness of the 21cm emission line. This is problematic due to the significant evolution of the Universe between the apparent peak of the cosmic star...
Intensity mapping is a technique which maps the unresolved flux of redshifted line emission in 3D. 21cm emission from neutral hydrogen (HI) is particularly useful as most HI in the post-reionisation Universe acts as a tracer of large-scale structure. These scales can provide insights into the most important questions in cosmology, such as constraining the nature of dark energy using BAO...
In this talk I will present an analysis of predicted radio galaxy morphologies for the Radio Galaxy Zoo (RGZ) catalogue, classified using a pre-trained radio galaxy foundation model designed with a view to the analysis of future SKA data. Our study examines over 14,000 radio galaxies, and provides predicted classifications for approximately 5,900 FRIs and 8,100 FRIIs. We investigate the...
Recent low-frequency radio observations have revealed a small sample of collimated synchrotron threads, or magnetic threads, in galaxy clusters. In particular, Ramatsoku et al. reported synchrotron threads connecting the radio lobes of ESO 137-006 using MeerKAT in 2020 and Rudnick et al. detected synchrotron threads extending away from the Northern radio lobe of 3C40B briefly thereafter. The...
The MeerKAT radio telescope in South Africa is a relatively new pathfinder of the Square Kilometre Array and is currently the most sensitive radio interferometer for neutral hydrogen (HI) studies with the 21-cm line. In this talk I present recent results and ongoing research from MeerKAT observations showcasing its strengths in this area. One set of results comes from follow-up of fast radio...
Many recent self-supervised learning (SSL) algorithms are based on encoding different "views" of the same image into a common latent space, e.g., BYOL, DINO. These views are typically augmentations of the input, such as rotations, reflections, magnifications, etc. Recent work on self-supervised learning for radio astronomy has shown that the choice of augmentation used for these views can...
