Abstract: EMU is now about 20% complete in terms of the observations. It is supporting a broad range of science, spanning star formation and evolution in our own Galaxy, galaxy evolution and the links between star formation and supermassive black holes, to cosmology, with well over 60 refereed papers to date. I will summarise the current status of and timeline for the survey, highlight a selection of recent results, and discuss next steps for EMU data products and science goals.

Abstract: I will present the Polarization Sky Survey of the Universe's Magnetism (POSSUM), one of ASKAP's major survey science projects that is being observed commensally with both EMU and WALLABY. POSSUM key goal is to provide Faraday rotation measures (RM) for at least an order of magnitude more radio sources than ever before observed, revealing information about the physical properties of the intervening magnetic field and will answer many important scientific questions such as: what is the role of cosmic magnetic fields in the evolution of galaxies and large scale structure? and what is the nature of the magnetic fields of the Milky Way and nearby galaxies? I will provide an overview of the current status and future plans for the survey and highlight some of the exciting science.

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Abstract: How to interact with data: demo and hand-on session.

Abstract: The innovative capabilities of CSIRO's ASKAP radio telescope has stretched the current generation of available computing platforms to their limit, demonstrating that while the big-data era of radio astronomy is difficult to navigate, it can be managed. This is not a scenario unique to ASKAP, and there has been a great deal of community development towards producing advanced and scalable pipeline management frameworks. Here we present 'Flint', a data-processing pipeline designed for ASKAP, written in python and managed by Prefect. We will highlight its current set of capabilities, which include full Stokes bandpass calibration, deconovolution using WSClean and self-calibration through CASA. Early results from reprocessing of RACS and EMU datasets will be presented.

Abstract: Clusters of galaxies have been found to host Mpc-scale diffuse, non-thermal radio emission in the form of central radio halos and peripheral relics. Turbulence and shock-related processes in the intra-cluster medium are generally considered responsible for the emission, though details of these processes are still not clear. The low-surface brightness makes detection of the emission a challenge, but with recent surveys with high-sensitivity radio telescopes we are beginning to build large samples of these sources. To assess prospects of EMU to help in building these samples, we have performed a pilot search of diffuse sources in 71 clusters from the Planck Sunyaev-Zeldovich (SZ) cluster catalogue (PSZ2) found in archival ASKAP observations, including EMU pilot data. This talk will highlight this pilot project, and report on the new source detections and the prospects for the full survey.

Abstract:Merging galaxy clusters, as cosmic laboratories for studying dark matter, frequently exhibit radio relics—diffuse radio emissions generated by colliding clusters. These relics are crucial for understanding the details of the history of the merger. While only about one hundred are currently known, the upcoming Square Kilometre Array (SKA) is expected to discover a few hundred to thousands, given the increased sensitivity. Efficiently detecting these relics in vast data volumes is a significant challenge. This presentation introduces a novel approach to automatically identify radio relics in the EMU data using complexity and Haralick texture features. Apparent complexity, a value quantifying image intricacy, is particularly high for radio relics due to their complex morphological structures. Haralick texture features derived from the gray-level co-occurrence matrix provide additional discriminatory information about image patterns. By combining these techniques, we aim to develop a robust automated pipeline for radio relic detection.

Abstract: Star-forming edge-on galaxy that has been observed to exhibit extended halo radiation in multiple bands, making it an ideal laboratory for studying the transfer of matter from the disk to the halo. Low-frequency radio continuum studies can help to further understand how cosmic-ray electrons (CRe) propagate through the interstellar medium into the halo and how this is affected by energy losses and magnetic fields. Using observations from the Australian Square Kilometre Array Pathfinder (ASKAP) at 944 MHz, we obtained the radio continuum image of NGC 253. Combining observations from the Very Large Array (VLA) and Effelsberg at 1.5 and 4.8 GHz, our objective is to identify the existing models of cosmic ray propagation in the NGC 253 galaxy. Cosmic ray electrons propagate advectively in the central region of the galaxy NGC 253, while they propagate diffusively in the outer regions.

Abstract: Combining optical integral field spectroscopy (IFS) with multi-wavelength data is transforming our view of the interstellar medium (ISM) of galaxies. I will present an overview of the TYPHOON survey, which obtained optical IFS of 44 very nearby (D<20Mpc; z~0), large angular-sized (>3') galaxies in the Southern Hemisphere. The TYPHOON galaxies have a wealth of data from optical to radio wavelengths, including EMU. I will highlight the current data overlap between TYPHOON and EMU and an overview of a few projects being undertaken by our team. TYPHOON is an open collaboration and this talk is intended to generate interest and cross-survey collaboration.

Abstract: We demonstrate the importance of radio selection in probing heavily obscured galaxy populations. Using Evolutionary Map of the Universe (EMU) Early Science data in the Galaxy and Mass Assembly (GAMA) G23 field together with GAMA and Wide-field Infrared Survey Explorer (WISE) data, we demonstrate that the radio detected population has on average higher levels of obscuration than the parent optical sample. This arises through missing the lowest BD and lowest mass galaxies, which are also the lower star formation rate (SFR) and metallicity systems. Possible explanations include speculation around steeper stellar initial mass functions in low mass, low SFR galaxies.

We further investigate the link between dust obscuration and SFR estimators using Halpha luminosities and radio luminosities. We explore this by drawing on dust estimates using both the BD and the dust mass, demonstrating systematic underlying dependencies with the radio-to-Halpha ratio. Defining two novel dust geometry metrics by combining the BD and dust mass, we confirm their utility as a way to quantify dust geometry. We use this approach to establish an improved estimator for the Halpha SFR that accounts for optically thick dust. We also establish a strong correlation between specific SFR and the dust opacity and geometry in galaxies.

Abstract: I will demonstrate how to visualise EMU data with CARTA via CASDA, within the context of the EMU validation process.

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Abstract: The EMU Pilot Survey Phase 2 (EMU PS2) is an equatorial field of 180 deg^2 observed in 2021 in six contiguous tiles at 944 MHz, with the same rms noise and angular resolution as EMU PS1 and the ongoing full EMU survey. I visually inspected the EMU PS2 mosaic, aided, where applicable, by higher-resolution VLASS or FIRST images, EMU PS2 is fully covered by optical images of the Dark Energy Survey DR10 and Pan-STARRS and partly by the CFHT Legacy Survey and SDSS Stripe 82. Optical spectroscopy is available from SDSS, GAMA-02h, DESI-EDR and XMM-LSS, and others. In total, the host galaxies of 672 radio galaxies (ERGs) with an angular extent >1' were identified. Spectroscopic redshifts were found for 40%, photometric ones for 59%, and for only 1% with very faint hosts a redshift of z∼1.5 was assumed, and used to derive their projected largest linear radio sizes (LLS). While 20 giant radio sources (GRS, LLS >0.7 Mpc, z_med=0.65) were published prior to EMU PS2, I identified 240 additional ones (z_med=0.75) in EMU PS2, or an increase by a factor of 12.

A cross-match with the largest and deepest catalogues of galaxy clusters (listing >20,000 clusters in the EMU PS2 field) reveals that about 25% of ERG hosts reside in galaxy clusters, and are predominantly associated with the brightest cluster galaxies. While the median LLS of ERGs in clusters is significantly smaller than those outside clusters, several large GRGs are (mostly brightest) cluster members. It thus appears that the extreme size of GRGs is due to either (a) their location in underdense regions of the Universe, allowing an unhindered expansion of the radio lobes, or to (b) the jets of the GRGs in clusters of galaxies being of higher power to penetrate the dense intracluster medium. Finally, there is no trend of a decreasing LLS at higher redshift, contrary to expectations from a hotter and denser Universe at earlier cosmological epochs.

Abstract: The determination of the distribution of Active Galactic Nuclei (AGN) across cosmic time is crucial for understanding the evolution of Supermassive Black Holes (SMBHs) and their connection to galaxy formation. A central tool for this analysis is the Luminosity Function (LF), that quantifies the number density of objects within a specific luminosity and redshift range. However, the limited number of radio-detected objects makes the construction of robust RLFs a difficult task. Future observatories promise to improve detection rates, but efficient methods are needed to analyse the massive datasets they will generate.

To address this task, Carvajal et al (2023) developed a machine learning (ML) based pipeline that, using multi-band, multi-instrument optical and infrared (IR) photometry, can efficiently identify large numbers of Radio Galaxy candidates and estimate their redshift. This pipeline is also versatile, allowing its application in different regions of the sky with moderately different photometric coverage from its training dataset.

We will present the results of the application of the ML-based pipeline to IR-detected sources in the area of the Pilot Survey of the Evolutionary Map of the Universe (EMU). Leveraging the expanded number of radio-detectable AGN and SFGs identified with our technique, we have also constructed a robust RLF incorporating necessary corrections from the performance of the ML models. Our results are in line with previous estimates, confirming the reliability of our approach for moderate-to-high redshifts. This RLF has the potential to constrain the density of sources in a broader redshift range than previous results, leading to a deeper understanding of AGN evolution, particularly in the early Universe.

Abstract: In the era of big data astronomy, extracting meaningful insights from vast and complex datasets has become increasingly crucial. Key missing pieces of the Universe's complex puzzle include the drivers of star formation (SF), its connection to AGN activity, AGN triggering itself, and the birth of the first supermassive black holes (SMBHs). Self-Organizing Maps (SOMs), unsupervised machine learning algorithms capable of clustering and visualizing high-dimensional data without relying on predefined models, offer a promising solution for gaining further insights into these questions. In the presence of present and future low spectroscopic coverage, the ability of SOMs to reveal underlying patterns and relationships between photometric properties and intrinsic galaxy characteristics makes them particularly valuable for a comprehensive understanding of galaxy populations, irrespective of their AGN or star-forming nature.

In this study, we demonstrate the power of SOMs by applying them to the photometric data of approximately 10 million sources selected from the Dark Energy Survey (DES). Our findings reinforce the effectiveness of SOMs for reliable and interpretable classifications and redshift predictions. Expanding their application to the radio domain, and mapping other intrinsic properties of AGN and galaxies, will offer crucial insights for understanding the rich data from the ASKAP/EMU survey.

Abstract: Galaxy clusters undergoing major mergers host spectacular megaparsec-scale diffuse radio sources called radio relics and radio halos. They are believed to originate from cosmic-ray electrons, which are (re-)accelerated by merger driven shocks and turbulence in the intracluster medium (ICM). However, the physics of the particle acceleration processes responsible for their origin and the interplay between different components of the ICM are not well understood. In this talk, I will discuss recent results obtained with the EMU and MeerKAT observations of Bullet, Abell 3186, and RXC J1314.4-2515 clusters. These observations reveal multicomponent halos and puzzling relations between thermal and non thermal plasma.

Abstract: Active galactic nuclei (AGN) are one of the most promising candidates as an origin of high-energy astrophysical neutrinos, with the two confirmed extragalactic neutrino sources to date both being radio-loud AGN. Indeed, there are a number of phenomena at play in AGN, such as shocks within jets and magnetic reconnection events, that provide plausible mechanisms for neutrino production. However, understanding the how much AGN contribute to the observed neutrino flux requires information from multiple messengers, and the current generation of radio surveys can provide key insights here. In this talk I present early evidence from the Very Large Array Sky Survey and the IceCube observatory that high energy neutrinos are associated with flaring radio sources. I will then discuss how the depth of EMU can contribute further to our understanding of AGN as neutrino factories by expanding the volume of the Universe over which we can make neutrino/radio associations.

Abstract: A high fraction of known radio pulsars are being detected in the early parts of the EMU and POSSUM surveys. We measure flux densities, rotation measures and spectral indices for pulsars from the ATNF catalog located in a subset of the observed and processed EMU and Possum fields (SBs) near the Galactic plane. Radio pulsars are compact objects, which requires that the measurements need to be assessed for the effects scintillation in the interstellar medium. The current status of the measurements and what new information they give us about the pulsars is discussed.

Abstract: Of the millions of radio galaxies being uncovered by EMU, which ones are most deserving of our attention? Which promise to give us the most insights into the questions that motivate us? Which will lead to successful proposals and funding, honor and glory? The answers to these questions can come into focus by repeatedly asking “so what?”. I’ll explore these issues, present my own idiosyncratic views, and briefly introduce Astronomaly: Protege, the machine learning creation of Michelle Lochner, which shows good promise for screening surveys for sources that I (or anyone who trains it) find especially interesting.

Abstract: The Australian Square Kilometre Array Pathfinder (ASKAP) is conducting the Polarisation Sky Survey of the Universe's Magnetism (POSSUM), aiming to map the southern sky in full polarisation with a sensitivity of approximately 15 microJy/beam per Stokes parameter at 17” resolution. As part of this, POSSUM has now collected approximately 200,000 Faraday Rotation Measures (RMs), making it the largest Faraday rotation measure (RM) grid experiment ever undertaken. Our research group is leveraging this unprecedented dataset to explore magnetised gas beyond the boundaries of galaxy, group, and cluster halos.

I will weave together results from several studies to illustrate the utility of Faraday rotation measure data in understanding how gas transits through the hierarchy of cosmic scales to ultimately form stars. This includes: (a) The detection of a shock between merging subcomponents of the Fornax cluster and our recent stacking analysis of galaxy groups, revealing magnetised gas extending beyond the virial radius of these structures and connecting to the cosmic web; (b) Our analysis of gas beyond the virial radius of massive clusters, including the Abell 3391/95 system, which shows an X-ray bright bridge illuminated with eROSITA; and (c) The tentative detection of magnetic fields in high-velocity clouds (HVCs) around the Milky Way, which may solve the problem of how HVCs remain intact during their transit through the Galactic halo into the star-forming disk.

We will emphasize the role of RM grids in revealing magnetized thermal gas at the peripheries of structures within the cosmic hierarchy of structure formation. Additionally, we will discuss how complementary techniques, such as X-ray, S-Z, and FRB observations, pave the way for future investigations into cosmic magnetic fields through astrophysical 'magnetic dye tracer' experiments in these dynamic regions.

Abstract: While merging massive galaxy clusters are among some of the most spectacular events in the Universe, the majority of galaxies reside not in these behemoths, but in smaller structures such as poor clusters and galaxy groups. In these lower-mass environments, phenomena related to active galactic nuclei (AGN) and member galaxies play a more significant role in the enrichment and evolution of the intra-group medium (IGrM) and its associated magnetic field. However, despite the importance of studying magnetic fields in these environments, they remain largely under-explored.

Compact groups in particular represent a golden opportunity to study the effects of feedback and interactions on the IGM. These dense structures display a particular wealth of interaction-driven phenomena, from morphological peculiarities and disturbances, to AGN activity and starbursts, to shocks and group-scale outflows.

Hickson Compact Group 15 (HCG15) represents an especially unusual and enigmatic galaxy group. Dominated not by a single giant elliptical galaxy but rather six galaxies with a mixed elliptical/lenticular population, it hosts extended thermal X-ray emission and diffuse intergalactic light but is deficient in neutral gas, and it also hosts an unusual diffuse radio source that has eluded classification until now.

New ASKAP observations from the EMU survey revealed that this diffuse emission is strongly polarised with a highly-ordered magnetic field, kickstarting a multi-wavelength follow-up campaign with LOFAR, the GMRT, the JVLA, and MeerKAT at S-band. In this talk, I will present the results of this campaign with a particular focus on our deep full-polarisation ASKAP and MeerKAT results. Our study sheds new light on the system, revealing the spectropolarimetric and thermal/non-thermal properties as well as the topography of the magnetoionic medium in unprecedented detail, finally allowing us to solve the mystery of HCG15’s nature.

Abstract: Pulsars and their Wind Nebulae (PWNe) exhibit intriguing features when moving at supersonic speeds through ambient medium such as bow-shaped shocks and cometary tails. Studying the PWNe provides valuable insights into pulsars, radiative efficiency, properties of the surrounding medium, and the physics of the wind-medium interaction. Additionally, it contributes to our understanding of the distribution of the natal kick velocities that neutron stars acquire during supernova implosions. The first report of this phenomenon dates to 1987, and prior to the Chandra X-ray Observatory's launch, only a handful of the PWNe had been identified. Chandra's enhanced capabilities have led to the identification of approximately 30 pulsars displaying signs of supersonic motion. However, recent advancements in radio-continuum surveys obtained with ASKAP and MeerKAT have transformed the rarity of these objects.

In this presentation, I will summarize the discovery and analysis of Potoroo, a remarkable bow-shock PWN with one of the longest radio tails, detected in the EMU pilot survey. The latter part of the talk will highlight the six best new examples of the class, showcasing a diverse range of morphologies. All discoveries have been made in the Galactic Plane fields of the EMU main survey, with promising prospects for more to come.

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Abstract: Three years after their discovery by EMU, we still know of only a handful of single Odd Radio Circles (ORCs) surround distant galaxies, although there are dozens of "ORC-ish" objects. The discovery of a new, small, faint ORC using Meerkat extends the parameter range to objects that could not be detected by EMU and enables us to put some constraints on their flux density distribution. This new ORC also surrounds a violently disturbed galaxy, favouring the galaxy merger or SMBH merger hypotheses for the origin of ORCs. In this talk I will define an ORC more carefully and estimate how many are likely to be found by EMU. (Spoiler: lots!).

Abstract: In this talk, I will present the consolidated value-added catalogs from the first year (~160 tiles) of the EMU main survey. These catalogs are constructed using deep learning-based object detection techniques developed in Gupta et al. 2024a,b, originally applied to the pilot survey. The cataloging pipeline for the main survey now includes orientation angle measurements for all extended radio sources. These catalogs feature consolidated extended and unresolved compact radio sources, along with their infrared/optical counterparts where available in the WISE and DESI Legacy surveys. Currently, the catalogs are undergoing validation through an extensive active learning process to refine the final object detection model. In addition to the catalogs, I will also present the first detections of new Odd Radio Circles (ORCs) and other peculiar radio sources in the main survey using our machine learning model.

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Abstract: In this work we use the angular power spectrum of the EMU Pilot Survey data and its cross-correlation with CMB lensing to put constraints on the clustering bias and the amplitude of the density fluctuations, sigma_8. After validating the data with two catalogue methods, we perform the analysis for different redshift distributions as from the radio galaxy simulation models and for two galaxy bias models. In addition, we consider linear and non-linear predictions for the underlying dark matter distribution and introduce different scale and flux cuts. We use an analytical covariance for the results which is validated with a numerical covariance.

Abstract: The redshifts of the radio sources are difficult to measure and it restricts our capabilities to make cosmological inferences using radio surveys. For cosmological analyses employing the angular power spectra, one of the key observable is the redshift distribution of sources. In this talk, we will present the estimation of redshift distribution of EMU Pilot Survey 1 by cross-correlating with Dark Energy Survey Y3 cosmology catalogue. We will compare the estimated EMU redshift distribution with the distributions from SKADS and TRECS simulations. We will also discuss the potential application of our method to the EMU main survey data.

Abstract: The existence of powerful AGN has been established well within the first Gyr of the Universe, through observations of tens of optically or near-infrared selected QSOs up to the currently highest redshift of z~8. Theoretical work supports the existence of supermassive (M∼10^9 Msun) black holes at even earlier epochs, depending on the fast assembly and growth of a suitable seed. Some of these sources should be bright at radio wavelengths, and detectable even within the Epoch of Reionisation. Such sources will be paramount to the understanding of the earliest stages of galaxy evolution but even more, as they should allow for the direct study of neutral hydrogen in the Epoch of Reionization, through SKA observations of the HI 21cm forest.

In spite of these high expectations, it has been essentially impossible for radio surveys to reveal such ""rosetta stone"" systems, allowing for an important ""detectability"" (do such sources even exist at such early times, or are they just later manifestations of the EoR “little red dots” revealed by JWST?) vs ""identification"" (inadequate multiwavelength coverage) discussion.

With the recent generation of SKA-percursor wide-deep radio surveys, however, by focusing on regions of the sky already hosting a comprehensive range of multiwavelength data, one may shed light on how the identification of EoR radio AGN can finally be achieved. Here, we will discuss recent strategies for the identification of the earliest radio-powerful AGN, highlighting recent work on MeerKAT’s MIGHTEE survey and how that is being applied to ASKAP’s EMU. We will also discuss how massive whole-sky radio surveys and coordination with powerful NIR-to-mm facilities, like MOONS, JWST and ALMA, will be essential in the leading-up to an even more ambitious SKA-ELT era.

Abstract: How to interact with data: demo and hand-on session.

Abstract: This talk explores the transformative impact of artificial intelligence (AI) on the future of astronomy. By leveraging AI's capabilities in data analysis, pattern recognition, and anomaly detection, astronomers can process vast datasets more efficiently, leading to groundbreaking discoveries of celestial objects and phenomena. AI-driven simulations and modeling enhance our understanding of cosmological structures and stellar evolution, while automated observatories and adaptive optics improve observational precision. As AI continues to evolve, it will drive interdisciplinary research, empower citizen scientists, and optimize next-generation astronomical instruments, ushering in a new era of astronomical discovery and expanding our understanding of the universe.

Abstract: After over 2.5 years of preparation, the Radio Galaxy Zoo: EMU (RGZ EMU) has recently went live. RGZ EMU is an EMU-initiated citizen science project (~65 team members) not only to associate interconnected radio emission regions and find their hosting objects, but also to identify their radio morphology via pre-selected tags. In this talk, I will talk about how we came up with the RGZ EMU designation and share some of its early results in the first 3-month project operation period. Finally, I will introduce our recent international effort in outreach and education.

Abstract: The most powerful radio galaxies act as beacons for galaxy over-densities in cluster haloes and tend to be hosted by extremely massive galaxies across cosmic time. While the literature deep fields and narrow-field space telescope observations investigate prolific clusters that shine brightly in the optical and infrared, deep wide-area radio observations from metre to millimetre wavelengths are finding complementary galaxy clusters, pinned down by high-redshift radio galaxies (HzRGs). We showcase a near-infrared (NIR)-dark proto-cluster at z=3.879, identified via a GLEAM radio galaxy and confirmed with widespread CO(4-3) detections in ALMA Band 3 scans. The candidate proto-cluster members associated with the molecular gas emission all severely lack optical to infrared detections in DES and deep (K ~ 24 AB) HAWK-I imaging, making this dark cluster only discoverable with wide-area surveys in the radio. We discuss the future prospects of EMU, in synergy with deep wide-area NIR surveys such as with Euclid, to discover even more dark or faint clusters in the southern sky footprint, probing even fainter radio emission of "anchors" such as HzRGs or the more diffuse, large-scale emission of the cosmic web.

Abstract: Building on the thesis work of Miranda Yew, we have compiled a catalog of over 3000 double-lobed AGN radio sources in the EMU-PS1 survey, including FRI/FRII, bent-tail galaxies, head-tail galaxies, X-shaped galaxies, etc. Each source has ben manually inspected, measured, classified, and a tentative IR/optical cross-ID assigned. This is the largest such catalogue so far assembled, and has two functions: (a) to serve as a training set of machine-learning algorithms, and (b) to explore the properties of the galaxies. They turn out to be rather different from the samples found at higher flux densities.

Abstract: A supermassive black hole resides in the centre of every galaxy. Some are active, resulting in observational features across the electromagnetic spectrum, and some are quiescent. Using the data from the Galaxy and Mass Assembly (GAMA) G23 region, the Evolutionary Map of the Universe (EMU) survey, and the Wide-field Infrared Survey Explorer (WISE) survey, we propose a new method for identifying active galactic nuclei (AGN) in low mass (M_stellar<=10^10 M_Sun) galaxies. The technique is compared with a selection of different AGN diagnostics to explore the similarities and differences in AGN classification. While diagnostics based on optical and near-infrared criteria (the standard BPT diagram, the WISE colour criterion, and the mass-excitation, or MEx diagram) tend to favour the detection of AGN in high mass, high luminosity systems, the “ProSpect” SED fitting tool can identify AGN efficiently in low mass systems. An explanation for this result is investigated in the context of proportionally lower mass black holes in lower mass galaxies compared to higher mass galaxies and differing proportions of emission from AGN and star formation dominating the light at optical and infrared wavelengths as a function of galaxy stellar mass. Using the same sets of data, we also measure the radio luminosity functions (LFs) of the G23 galaxies as a whole and for AGN and star formers separately. Redshifts and classifications are estimated using simple statistical techniques for those radio galaxies without spectroscopic data. The calculated LFs are compared with the existing studies, and the results suggest that the LFs match remarkably well for low redshift galaxies with an optical counterpart.

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Abstract: The well known (and very striking) planetary nebula NGC 5189 was first detected in radio back in 1965, by Slee & Orchiston at the Parkes observatory. From there onwards it received the most radio attention in the 1970s and early 80s, yet the time is nigh to contribute up-to-date measurements from the state-of-the-art radio telescopes and report accordingly. Hence, I will report on the radio continuum detection of NGC 5189, observed at 944 MHz during the ASKAP EMU main survey. My team and I have nicknamed it the ‘infinity nebula’, of which I will discuss the estimated flux and spectral measurements and compare to HST observations.

Abstract: The ASKAP EMU and POSSUM surveys have the potential to investigate supernova remnants (SNRs) with small angular sizes and low surface brightness. In this talk, I will report the discovery of the radio shell of SNR G310.6-1.6 using the joint surveys. We also detected polarized emission from the central pulsar wind nebula (PWN) and obtained a rotation measure (RM).

The structure of SNR G310.6-1.6 is unique, featuring a circular radio shell outside a circular hard X-ray shell, which is unusual among known SNRs. Combining radio and X-ray observations, we will discuss various scenarios to explain the observed characteristics of the shells.

Abstract: The bright radio source, GLEAM J091734-001243 (hereafter J0917), was previously selected as a candidate ultra-high (z>5) redshift radio galaxy due to its compact radio size and faint magnitude, K(AB)=22.7. Its redshift was not conclusively determined from follow-up millimetre and near-infrared spectroscopy. Here we present new HST WFC3 G141 grism observations which reveal several emission lines including [NeIII]lambda3426, [NeV]lambda3463 and a wide (FWHM> 3,000 km/s), and extended (~4.8 kpc), [OII]lambda3727 line which confirm a redshift of 3.0035+/-0.0007. The extended component of the [OIII]lambda3727 line is strongly redshifted and co-spatial with one of two components seen at 2.276 GHz in high resolution (60 x 20 mas) long baseline array data. J0917 has a mass (from UV/optical modelling) and radio luminosity within the distribution of the brightest high-redshift radio galaxies at similar redshifts. However, it is more compact than all of them. Modelling of the radio jet demonstrates that this is a young, ~50kyr, but powerful, ~10^39 W, compact steep spectrum radio source. The weak constraint on the AGN bolometric luminosity from the [NeV]lamba3426 line combined with the modelled jet power implies a large black hole mass, >10^9 Msun, and a low, advection-dominated accretion rate, Eddington rate <0.03$. The [NeV]lambda3426/[NeIII]lambda3867 v [OII]lambda3727/[NeIII]lambda3867 line ratios are most easily explained by radiative shock models with precursor photoionisation. Hence, we infer that the line emission is directly caused by the shocks from the jet and that this radio source is one of the youngest and most powerful at cosmic noon.

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