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The SKA PAthfinder Radio Continuum Surveys (SPARCS) are providing deep-field imaging of the faint (sub-mJy) extra-galactic radio source populations through a series of reference surveys. One of the key science goals for SPARCS is to characterize the relative contribution of radio emission associated with AGN from star-formation (SF) in these faint radio source populations, using a combination of high sensitivity and high angular resolution imaging over a range of spatial scales (arcsec to mas). To isolate AGN contribution from SF, we hypothesise that there exists a brightness temperature cut-off point separating pure AGN from SF. We present a multi-resolution (10-100 mas) view of the transition between compact AGN and diffuse SF through a deep wide-field EVN+e-MERLIN, multiple phase centre survey of the centre of the Northern SPARCS (SLOAN) reference field at 1.6 GHz. This is the first (and only) VLBI (+e-MERLIN) milliarcsecond angular resolution observation of this field, and of the wider SPARCS reference field programme. Using these high spatial resolution (9 pc - 0.3 kpc at z ~ 1.25) data, 11 milliarcsecond-scale sources are detected from a targeted sample of 52 known radio sources from previous observations with the e-MERLIN, giving a VLBI detection fraction of ~ 21%. At spatial scales of ~ 9 pc, these sources show little to no jet structure whilst at ~ 0.3 kpc one-sided and two-sided radio jets begin to emerge on the same sources, indicating a possible transition from pure AGN emissions to AGN and star-formation systems., 14 pages, 10 figures

Monthly notices of the Royal Astronomical Society 515(1), 1365 - 1379 (2022). doi:10.1093/mnras/stac1601, We report on a search for persistent radio emission from the one-off fast radio burst (FRB) 20190714A, as well as from two repeating FRBs, 20190711A and 20171019A, using the MeerKAT radio telescope. For FRB 20171019A, we also conducted simultaneous observations with the High-Energy Stereoscopic System (H.E.S.S.) in very high-energy gamma rays and searched for signals in the ultraviolet, optical, and X-ray bands. For this FRB, we obtain a UV flux upper limit of |$1.39 \times 10^{-16}~{\rm erg\, cm^{-2}\, s^{-1}}$|Å^−1, X-ray limit of |$\sim 6.6 \times 10^{-14}~{\rm erg\, cm^{-2}\, s^{-1}}$| and a limit on the very high energy gamma-ray flux |$\Phi (E\gt 120\, {\rm GeV}) \lt 1.7\times 10^{-12}\, \mathrm{erg\, cm^{-2}\, s^{-1}}$|⁠. We obtain a radio upper limit of ∼15 |$\mu$|Jy beam^−1 for persistent emission at the locations of both FRBs 20190711A and 20171019A with MeerKAT. However, we detected an almost unresolved (ratio of integrated flux to peak flux is ∼1.7 beam) radio emission, where the synthesized beam size was ∼ 8 arcsec size with a peak brightness of |$\sim 53\, \mu$|Jy beam^−1 at MeerKAT and |$\sim 86\, \mu$|Jy beam^−1 at e-MERLIN, possibly associated with FRB 20190714A at z = 0.2365. This represents the first detection of persistent continuum radio emission potentially associated with a (as-yet) non-repeating FRB. If the association is confirmed, one of the strongest remaining distinction between repeaters and non-repeaters would no longer be applicable. A parallel search for repeat bursts from these FRBs revealed no new detections down to a fluence of 0.08 Jy ms for a 1 ms duration burst., Published by Oxford Univ. Press, Oxford

We present new imaging of a sub-kpc-scale binary active galactic nucleus (AGN) candidate from the Karl G. Jansky Very Large Array (VLA) and the Multi-Element Radio Linked Interferometer Network (e-MERLIN). Two unresolved radio sources of similar luminosity around 1022 WHz−1 are identified in ∼35 h of e-MERLIN 6 cm imaging. These radio sources have an angular separation of 0.19 ± 0.06 arcsec and position angle (PA) of 22° ± 10°, corresponding to a projected separation of 0.95 ± 0.29 kpc at the epoch of the source. Our results suggest the presence of a kpc-scale active black hole pair hosted by two galaxies in the late stage of a merger at z = 0.35. This work follows Woo et al., which presented two optical sources with a similar separation and PA, and a velocity separation of 200 km s−1. Our target adds to the currently limited sample of close-separation binary AGNs, which will aid in understanding the frequency of mergers and the stochastic gravitational wave background.

Full list of authors: Muxlow, T. W. B.; Thomson, A. P.; Radcliffe, J. F.; Wrigley, N. H.; Beswick, R. J.; Smail, Ian; McHardy, I. M.; Garrington, S. T.; Ivison, R. J.; Jarvis, M. J.; Prandoni, I.; Bondi, M.; Guidetti, D.; Argo, M. K.; Bacon, David; Best, P. N.; Biggs, A. D.; Chapman, S. C.; Coppin, K.; Chen, H.; Garratt, T. K.; Garrett, M. A.; Ibar, E.; Kneib, Jean-Paul; Knudsen, Kirsten K.; Koopmans, L. V. E.; Morabito, L. K.; Murphy, E. J.; Njeri, A.; Pearson, Chris; Pérez-Torres, M. A.; Richards, A. M. S.; Röttgering, H. J. A.; Sargent, M. T.; Serjeant, Stephen; Simpson, C.; Simpson, J. M.; Swinbank, A. M.; Varenius, E.; Venturi, T., We present an overview and description of the e-MERGE Survey (e-MERLIN Galaxy Evolution Survey) Data Release 1 (DR1), a large program of high-resolution 1.5-GHz radio observations of the GOODS-N field comprising similar to 140 h of observations with enhanced-Multi-Element Remotely Linked Interferometer Network (e-MERLIN) and similar to 40 h with the Very Large Array (VLA). We combine the long baselines of e-MERLIN (providing high angular resolution) with the relatively closely packed antennas of the VLA (providing excellent surface brightness sensitivity) to produce a deep 1.5-GHz radio survey with the sensitivity (similar to 1.5 mu Jy beam(-1)), angular resolution (0.2-0.7 arcsec) and field-of-view (similar to 15x15 arcmin(2)) to detect and spatially resolve star-forming galaxies and active galactic nucleus (AGN) at z greater than or similar to 1. The goal of e-MERGE is to provide new constraints on the deep, sub-arcsecond radio sky which will be surveyed by SKA1-mid. In this initial publication, we discuss our data analysis techniques, including steps taken to model in-beam source variability over an similar to 20-yr baseline and the development of newpoint spread function/primary beam models to seamlessly merge e-MERLIN and VLA data in the uv plane. We present early science results, including measurements of the luminosities and/or linear sizes of similar to 500 galaxies selected at 1.5 GHz. In combination with deep Hubble Space Telescope observations, we measure a mean radio-to-optical size ratio of r(e-MERGE)/r(HST) similar to 1.02 +/- 0.03, suggesting that in most high-redshift galaxies, the similar to GHz continuum emission traces the stellar light seen in optical imaging. This is the first in a series of papers that will explore the similar to kpc-scale radio properties of star-forming galaxies and AGN in the GOODS-N field observed by e-MERGE DR1. © 2020 The Author(s)., APT, TWBM, RJB, and MAG acknowledge support from STFC (ST/P000649/1). APT further acknowledges and thanks Robert Dickson, Peter Draper, David Hempston, Anthony Holloway, and Alan Lotts for their extensive support managing the highperformance computing infrastructure, which has been essential for the successful delivery of e-MERGE DR1. JFR acknowledges the financial assistance of the South African Radio Astronomy Observatory (SARAO) towards this research (http://sarao.ac.za).IP acknowledges support from INAF under the PRIN SKA/CTA project 'FORECaST' and the PRIN MAIN STREAM project 'SAuROS'. EI acknowledges partial support from FONDECYT through grant no 1171710. We thank the anonymous reviewer for their detailed and constructive referee report, which has undoubtedly improved the quality of the final manuscript. e-MERLIN is a National Facility operated by the University of Manchester at Jodrell Bank Observatory on behalf of STFC. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The authors acknowledge the use of the IRIDIS High Performance Computing Facility, and associated support services at the University of Southampton, in the completion of this work. We thank IRIS (www.iris.ac.uk) for provision of highperformance computing facilities. STFC IRIS is investing in the UK's Radio and mm/sub-mm Interferometry Services in order to improve data quality and throughput. The European VLBI Network is a joint facility of independent European, African, Asian, and North American radio astronomy institutes. Scientific results from data presented in this publication are derived from the following EVN project code(s): EG078B. The research leading to these results has received funding from the European Commission Horizon 2020 Research and Innovation Programme under grant agreement no. 730562 (RadioNet)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation SEV-2017-0709.

We measure the evolution of sizes for star-forming galaxies as seen in 1.4 GHz continuum radio for z = 0-3. The measurements are based on combined VLA+MERLIN data of the Hubble Deep Field, and using a uv-stacking algorithm combined with model fitting to estimate the average sizes of galaxies. A sample of similar to 1000 star-forming galaxies is selected from optical and near-infrared catalogues, with stellar masses Me-circle dot approximate to 10(10)-10(11) M-circle dot and photometric redshifts 0-3. The median sizes are parametrized for stellar mass M-* = 5 x 10(10) M-circle dot as R-e = A x (H(z)/H(1.5))(alpha z). We find that the median radio sizes evolve towards larger sizes at later times with alpha(z) = 1.1 +/- 0.6, and A (the median size at z approximate to 1.5) is found to be 0 ''.26 +/- 0 ''.07 or 2.3 +/- 0.6 kpc. The measured radio sizes are typically a factor of 2 smaller than those measure in the optical, and are also smaller than the typical H alpha sizes in the literature. This indicates that star formation, as traced by the radio continuum, is typically concentrated towards the centre of galaxies, for the sampled redshift range. Furthermore, the discrepancy of measured sizes from different tracers of star formation, indicates the need for models of size evolution to adopt a multiwavelength approach in the measurement of the sizes star-forming regions.

Insights from satellite observations are increasingly being used to enhance\ud a range of domains from highly specialised scientific research through to\ud everyday applications directly benefiting members of the public. A particular category\ud of satellite observations - Earth Observations (EO) - are concerned with\ud capturing information regarding the Earth’s atmospheric and environmental conditions\ud and observing human activity and its impact on the Earth’s surface. A growing\ud number of technologies and services heavily rely on EO data and the rapidly\ud improving fidelity, coverage, timeliness and accessibility of such observations are\ud providing significant opportunities for new applications of economic and societal\ud benefit. With the increasing importance, relevance and size of EO datasets, it is\ud critical to understand how the value of such data can be maximised by complementing\ud EO with other sources of data and efficiently making complex interpretations\ud and decisions. The wide adoption and availability of smartphones, Internet\ud devices and increased accessibility to information has paved the way for large\ud numbers of citizens and communities to participate in scientific, technological, societal\ud and decision making activities. This chapter discusses the experience of the\ud European Space Agency funded Crowd4Sat project led by the University of Sheffield\ud that investigated different facets of how crowdsourcing and citizen science\ud impact upon the validation, use and enhancement of Observations from Satellites\ud products and services.

The impact of Crowdsourcing and citizen science activities on academia, businesses, governance and society has been enormous. This is more prevalent today with citizens and communities collaborating with organizations, businesses and authorities to contribute in a variety of manners, starting from mere data providers to being key stakeholders in various decision-making processes. The “Crowdsourcing for observations from Satellites” project is a recently concluded study supported by demonstration projects funded by European Space Agency (ESA). The objective of the project was to investigate the different facets of how crowdsourcing and citizen science impact upon the validation, use and enhancement of Observations from Satellites (OS) products and services. This paper presents our findings in a stakeholder analysis activity involving participants who are experts in crowdsourcing, citizen science for Earth Observations. The activity identified three critical areas that needs attention by the community as well as provides suggestions to potentially help in addressing some of the challenges identified.