Research Articles (Physics)
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Item Hers-3: an exceptional einstein cross reveals a massive dark matter halo(Institute of Physics, 2025) Baker, Andrew J.; Cox, Pierre; Butler, Kirsty M.We present a study of HerS-3, a dusty star-forming galaxy at zspec = 3.0607, which is gravitationally amplified into an Einstein cross with a fifth image of the background galaxy seen at the center of the cross. Detailed 1 mm spectroscopy and imaging with NOEMA and the Atacama Large Millimeter/submillimeter Array resolve the individual images and show that each of the five images display a series of molecular lines that have similar central velocities, unambiguously confirming that they have identical redshifts. The Hubble Space Telescope F110W image reveals a foreground lensing group of four galaxies with a photometric redshift zphot ∼ 1.0. Lens models that only include the four visible galaxies are unable to reproduce the properties of HerS-3. By adding a fifth massive component, lying southeast of the brightest galaxy of the group, the source reconstruction is able to match the peak emission, shape, and orientation for each of the five images. The fact that no galaxy is detected near that position indicates the presence of a massive dark matter halo in the lensing galaxy group. In the source plane, HerS-3 appears as an infrared luminous starburst galaxy seen nearly edge on. The serendipitous discovery of this exceptional Einstein cross offers a potential laboratory for exploring at small spatial scales a nuclear starburst at the peak of cosmic evolution and studying the properties of a massive dark matter halo associated with the lensing galaxy group.Item The superMIGHTEE project: meerkat and GMRT together to unveil the deep radio sky(Institute of Physics, 2025) Taylor, Russ A.; Lal, Dharam Vir; Sekhar, SrikrishnaAn international team of researchers has come together to undertake an ultra-broadband exploration of the deep radio sky. The superMIGHTEE project combines data from the MIGHTEE project, using the precursor Square Kilometre Array MeerKAT telescope in South Africa, with observations from the upgraded Giant Metrewave Radio Telescope (uGMRT) in India to produce deep images at several μJy sensitivity over a frequency range of 200 MHz-2.5 GHz, with an angular resolution of a few arcseconds. This paper describes the initial superMIGHTEE uGMRT data release, comprising total intensity continuum images covering a total of 9.9 deg2 at 650 MHz and 6.9 deg2 at 400 MHz in the XMM-LSS, COSMOS, and E-CDFS deep fields. The associated radio source catalogues include 27,101 sources at 650 MHz and 10,946 sources at 400 MHz. The redshift distribution of the sources extends to z ∼ 4 with a median value of z = 1. An overview of the broadband spectra of the sources, in combination with the MeerKAT MIGHTEE 1280 MHz data, reveals a clear change in spectral properties at the transition from an active galactic nuclei-dominated population to a population dominated by star-forming galaxies at flux densities of a few mJy. At higher frequencies, the star-forming galaxy population exhibits an optically thin synchrotron spectral index indicative of energy injection from supernovae. At lower frequencies, the spectra flatten significantly with decreasing flux density, and the fraction of sources with peaked spectra increases. This is the first superMIGHTEE uGMRT data release. Subsequent releases will include spectro-polarimetric and spectral line image cubes, as well as images at lower frequencies. The goal of the superMIGHTEE ultra-wideband data set is to enhance our understanding of the evolution of active galactic nuclei and star-forming galaxies over cosmic time, shed light on the evolution of neutral hydrogen, and explore the origins and evolution of cosmic magnetic fields in clusters, filaments, and galaxies.Item Detecting local and integrated relativistic effects by multi-tracing a single galaxy population in harmonic space(Elsevier B.V., 2025) Novara, Marco; Montano, Federico; Camera, StefanoMeasuring relativistic effects on cosmological scales would provide further confirmation of the validity of general relativity in the still poorly tested condition of weak gravity. Despite their relevance, relativistic imprints in the distribution of galaxies on large scales have so far eluded detection, mainly because they are stronger on the largest cosmic scales, which are plagued by cosmic variance. Expanding on previous works, we study galaxy clustering by subdividing a galaxy population into two sub-samples – bright and faint – and we here focus on their two-point correlation function in harmonic space, i.e. via the angular power spectrum. Thanks to such a split in magnitude and by exploiting the multi-tracer technique, we are able to boost the impact of the relativistic contributions. We first focus on the leading relativistic contribution given by the Doppler effect and show that, with a carefully tailored luminosity cut, it can be detected. Then, we look at the sub-dominant effects predicted by general relativity and quantify how their statistical significance, as yet undetectable, varies with redshift binning and survey specifications. As case studies, we consider in our forecasts a bright galaxy sample at low redshift, an Hα emission-line galaxy survey at intermediate redshifts, and high-redshift Lyman-break galaxies at high redshift.Item MIGHTEE-H i: the MHi - M∗ relation of massive galaxies and the Hi mass function at 0.25 < z < 0.5(Oxford University Press, 2025) Jarvis, Matt J; Santos, Mario G.; Pan, HengxingThe relationship between the already formed stellar mass in a galaxy and the gas reservoir of neutral atomic hydrogen, is a key element in our understanding of how gas is turned into stars in galaxy haloes. In this paper, we measure the relation based on a stellar-mass selected sample atItem Stellar processes driven by the rise of nuclear collectivity(Springer, 2025) Orce, José NicolásThe sudden rise of nuclear collectivity above the pairing gap is revealed in this work as the primary source for the relative increase of the symmetry energy with respect to the ground state, as originally suggested by Donati and collaborators. This finding is uncovered by available data on giant dipole resonances built on excited states and 1h¯ω shell-model calculations of the myriads of products of electric dipole matrix elements that compose the nuclear dipole polarizability of the ground and first-excited states. At the temperatures involved in stellar environments, a larger symmetry energy impacts stellar collapse, the nucleosynthesis of heavy elements and the nuclear equation of state of hot neutron stars. According to the Pauli exclusion principle, the symmetry energy reduces the binding energy of nuclei with a larger number of neutrons N than protons Z. It is commonly given by the term −asym (A)(N − Z)2/A in the Bethe–Weizsäcker semi-empirical mass formula [1,2], where asym (A) is the symmetry energy parameter and A = N +Z the atomic mass number. Analog parametrizations of the symmetry energy can be found in the literature [3–6]. In a seminal work, Donati and collaborators [7] calculated a relative increase of the symmetry energy of approximately 2.5 MeV or 8% for mediummass nuclei in the temperature interval T = 0 − 1 MeV.Item Square kilometre array science data challenge 3a: foreground removal for an EoR experiment(Oxford University Press, 2025) Chatterjee, Suman; Wild, A.; Bonaldi, AnnaWe present and analyse the results of the Science Data Challenge 3a (SDC3a, https://sdc3.skao.int/challenges/foregrounds), an epoch of reionization (EoR) foreground-removal exercise organized by the Square Kilometre Array Observatory (SKAO) on SKA simulated data. The challenge ran for 8 months, from 2023 March to October. Participants were provided with realistic simulations of SKA-Low data between 106 and 196 MHz, including foreground contamination from extragalactic and Galactic emission, instrumental, and systematic effects. They were asked to deliver cylindrical power spectra of the EoR signal, cleaned from all corruptions, and the corresponding confidence levels. Here, we describe the approaches taken by the 17 teams that completed the challenge, and we assess their performance using different metrics. The challenge results provide a positive outlook on the capabilities of current foreground-mitigation approaches to recover the faint EoR signal from SKA-Low observations. The median error committed in the EoR power spectrum recovery is below the true signal for seven teams, although in some cases, there are some significant outliers. The smallest residual overall is cMpc across all considered scales and frequencies. The estimation of confidence levels provided by the teams is overall less accurate, with the true error being typically underestimated, sometimes very significantly. The most accurate error bars account for per cent of the true errors committed. The challenge results provide a means for all teams to understand and improve their performance. This challenge indicates that the comparison between independent pipelines could be a powerful tool to assess residual biases and improve error estimation.Item FAST drift scan survey for HI Intensity mapping: simulation of Bayesian-stacking-based HI mass function estimation(Institute of Physics, 2025) Hu, Wenkai; Wang, Jiaxin; Li, YichaoThis study investigates the estimation of the neutral hydrogen (Hi) mass function (HiMF) using a Bayesian stacking approach with simulated data for the Five-hundred-meter Aperture Spherical radio Telescope (FAST) Hi intensity mapping (HiIM) drift-scan surveys. Using data from the IllustrisTNG simulation, we construct Hi sky cubes at redshift 𝑧 ∼ 0.1 and the corresponding optical galaxy catalogs, simulating FAST observations under various survey strategies, including pilot, deep-field, and ultradeep-field surveys. The HiMF is measured for distinct galaxy populations– classified by optical properties into red, blue, and bluer galaxies– and injected with systematic effects such as observational noise and flux confusion caused by the FAST beam. The results show that Bayesian stacking significantly enhances HiMF measurements. For red and blue galaxies, the HiMF can be well constrained with pilot surveys, while deeper surveys are required for the bluer galaxy population. Our analysis also reveals that sample variance dominates over observational noise, emphasizing the importance of wide-field surveys to improve constraints. Furthermore, flux confusion shifts the HiMF toward higher masses, which we address using a transfer function for correction. Finally, we explore the effects of intrinsic sample incompleteness and propose a framework to quantify its impact. This work lays the groundwork for future HiMF studies with FAST HiIM, addressing key challenges and enabling robust analyses of Hi content across galaxy populations.Item Litmus tests of the flat ΛCDM model and model-independent measurement of H 0 r d with LSST and DESI(Institute of Physics, 2025) Koo, Hanwool; L'Huillier, Benjamin; Mitra, AyanIn this analysis we apply a model-independent framework to test the flat ΛCDM cosmology using simulated SNIa data from the upcoming Legacy Survey of Space and Time (LSST) and combined with simulated Dark Energy Spectroscopic Instrument (DESI) five-years Baryon Acoustic Oscillations (BAO) data. We adopt an iterative smoothing technique to reconstruct the expansion history from SNIa data, which, when combined with BAO measurements, facilitates a comprehensive test of the Universe's curvature and the nature of dark energy. The analysis is conducted under four different mock fiducial cosmologies: two curvatures (Ωk ,0 = 0 and 0.1) and two models of dark energy: a cosmological constant Λ and the phenomenologically emergent dark energy. We forecast that our reconstruction technique can constrain cosmological parameters, such as the curvature (k ,0) and c/H 0 r d, with spread due to the SNIa uncertainties up to ±4% and ±0.1 respectively, without assuming any form of dark energy.Item Nuclear level density and γ -ray strength function of Ni 67 and the impact on the i process(American Physical Society, 2025) Abrahams, Kenzo J; Ingeberg, Vetle Wegner; Siem, SunnivaProton-γ coincidences from (d,p) reactions between a Ni66 beam and a deuterated polyethylene target have been analyzed with the inverse-Oslo method to find the nuclear level density (NLD) and γ-ray strength function (γSF) of Ni67. The Ni66(n,γ) capture cross section has been calculated using the Hauser-Feshbach model in TALYS using the measured NLD and γSF as constraints. The results confirm that the Ni66(n,γ) reaction acts as a bottleneck when relying on one-zone nucleosynthesis calculations. However, the impact of this reaction is strongly dampened in multizone models of low-metallicity AGB stars experiencing i-process nucleosynthesis.Item New hope for obscured AGN: the PRIMA-NewAthena alliance(SPIE, 2025) Vaccari, Mattia; Barchiesi, Luigi; Carrera, FranciscoUnderstanding the AGN-galaxy co-evolution, feedback processes, and the evolution of Black Hole Accretion rate Density (BHAD) requires accurately estimating the contribution of obscured Active Galactic Nuclei (AGN). However, detecting these sources is challenging due to significant extinction at the wavelengths typically used to trace their emission. We evaluate the capabilities of the proposed far-infrared observatory PRIMA and its synergies with the X-ray observatory NewAthena in detecting AGN and in measuring the BHAD. Starting from X-ray background synthesis models, we simulate the performance of NewAthena and of PRIMA in Deep and Wide surveys. Our results show that the combination of these facilities is a powerful tool for selecting and characterizing all types of AGN. Although NewAthena is particularly effective at detecting the most luminous, the unobscured, and the moderately obscured AGN, PRIMA excels at identifying heavily obscured sources, including Compton-thick AGN (of which we expect 7500 detections per deg2). We find that PRIMA will detect ∼60 times more sources than Herschel over the same area and will allow us to accurately measure the BHAD evolution up to z ∼ 8, better than any current IR or X-ray survey, finally revealing the true contribution of Compton-thick AGN to the BHAD evolutionItem Search for Higgs boson decays into a pair of pseudoscalar particles in the γγτhadτhad final state using pp collisions at s = 13 TeV with the ATLAS detector(Springer Science and Business Media Deutschland GmbH, 2025) Leeuw, Lerothodi; Aad, Georges; Aakvaag, ErlendA search for exotic decays of the 125 GeV Higgs boson into a pair of new spin-0 particles, H → aa, where one decays into a photon pair and the other into a τ-lepton pair, is presented. Hadronic decays of the τ-leptons are considered and reconstructed using a dedicated tagger for collimated τ-lepton pairs. The search uses 140 fb−1 of proton-proton collision data at a centre-of-mass energy of s = 13 TeV recorded between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider. The search is performed in the mass range of the a boson between 10 GeV and 60 GeV. No significant excess of events is observed above the Standard Model background expectation. Model-independent upper limits at 95% confidence level are set on the branching ratio of the Higgs boson to the γγττ final state, B(H → aa → γγττ), ranging from 0.2% to 2%, depending on the a-boson mass hypothesis.Item Planck constraints on the scale dependence of isotropic cosmic birefringence(Institute of Physics, 2025) Ballardini, Mario; Gruppuso, Alessandro; Paradiso, SimoneThe rotation of the linear polarisation plane of photons during propagation, also known as cosmic birefringence, is a powerful probe of parity-violating extensions of standard electromagnetism. Using Planck legacy data, we confirm previous estimates of the isotropic birefringence angle, finding β ≃ 0.30±0.05 [deg] at 68% CL, not including the systematic error from the instrumental polarisation angle. If this is a genuine signal, it could be explained by theories of Chern-Simons-type coupled to electromagnetism, which could lead to a harmonic scale-dependent birefringence signal, if the hypothesis of an ultra-light (pseudo) scalar field does not hold. To investigate these models, we pursue two complementary approaches: first, we fit the birefringence angle estimated at different multipoles, βℓ, with a power-law model and second, we perform a non-parametric Bayesian reconstruction of it. Both methods yield results consistent with a non-vanishing constant birefringence angle. The first method shows no significant dependence on the harmonic scale (up to 1.8σ CL), while the second method demonstrates that a constant model is favored by Bayesian evidence. This conclusion is robust across all four published Planck CMB solutions. Finally, we forecast that upcoming CMB observations by Simons Observatory, LiteBIRD and a wishful CMB-Stage 4 experiment could reduce current uncertainties by a factor of approximately 7Item MIGHTEE: the continuum survey data release 1(Oxford University Press, 2025) Jarvis, Matthew J.; An, Fangxia; Hale, Catherine LauraThe MeerKAT International GHz Tiered Extragalactic Exploration Surv e y (MIGHTEE) is one of the large surv e y projects using the MeerKAT telescope, co v ering four fields that have a wealth of ancillary data available. We present Data Release 1 of the MIGHTEE continuum surv e y, releasing total intensity images and catalogues o v er ∼20 de g 2 , across three fields at ∼1.2-1.3 GHz. This includes 4.2 de g 2 o v er the Cosmic Evolution Surv e y (COSMOS) field, 14.4 de g 2 o v er the XMM Large-Scale Structure (XMM-LSS) field and deeper imaging o v er 1.5 de g 2 of the Extended Chandra Deep Field South (CDFS). We release images at both a lower resolution (7-9 arcsec) and higher resolution ( ∼5 arcsec). These images have central rms sensitivities of ∼1 . 3 -2.7 μJy beam -1 ( ∼1 . 2 -3.6 μJy beam -1 ) in the lower (higher) resolution images, respectively. We also release catalogues comprised of ∼144 000 ( ∼114 000) sources using the lower (higher) resolution images. We compare the astrometry and flux-density calibration with the Early Science data in the COSMOS and XMM-LSS fields and previous radio observations in the CDFS field, finding broad agreement. Furthermore, we extend the source counts at the ∼10 μJy level to these larger areas ( ∼20 deg 2 ) and, using the areal co v erage of MIGHTEE we measure the sample variance for differing areas of sky. We find a typical sample variance of 10 -20 per cent for 0.3 and 0.5 de g 2 subre gions at S 1 . 4 ≤200 μJy, which increases at brighter flux densities, given the lower source density and expected higher galaxy bias for these sources.Item Radio galaxies in Simba: a mightee comparison(Oxford University Press, 2025) Whittam, Imogen H; Davé, Romeel; Jarvis, Matt JWe present a qualitative comparison between the host and black hole properties of radio galaxies in the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey with the radio galaxy population in the SIMBA suite of cosmological hydrodynamical simulations. The MIGHTEE data include a ∼1 deg2 pointing of the COSMOS field observed at 1.28 GHz with the MeerKAT radio telescope and cross-matched with multiwavelength counterparts to provide classifications of high- and low-excitation radio galaxies (HERGs and LERGs) along with their corresponding host properties. We compare the properties of the MIGHTEE HERGs and LERGs with that predicted by the SIMBA simulations where HERGs and LERGs are defined as radio galaxies dominated by cold or hot mode accretion, respectively. We consider stellar masses M∗, star formation rates SFR, AGN bolometric luminosity Lbol, and Eddington fraction fEdd, as a function of 1.4 GHz radio luminosity and redshift. In both MIGHTEE and SIMBA, the properties of HERGs and LERGs are similar across all properties apart from SFRs due to differences in host cold gas content in SIMBA. We predict a population of HERGs with low fEdd in SIMBA that are confirmed in the MIGHTEE observations and tied to the faint population at low z. The predictions from SIMBA with the MIGHTEE observations describe a regime where our understanding of the radio galaxy dichotomy breaks down, challenging our understanding of the role of AGN accretion and feedback in the faint population of radio galaxies.Item Physical properties and the magnetocaloric effect in Ho2Pt2In(Elsevier B.V., 2025) Mboukam, Jean Jules; Tchoula Tchokonté M.B.; Mpupa, Zanele ZandilePolycrystalline samples of Ho2Pt2In were studied by means of low-temperature electrical resistivity, ρ(T), heat capacity, Cp(T), magnetic susceptibility, χ(T), and magnetization, M(H) measurements. The compound was found to undergo a paramagnetic to ferromagnetic phase transition at TC = 18 K and another phase transition at T1 = 8.3 K, likely a magnetic structure reconstruction into an antiferromagnetic-like state. Furthermore, magnetocaloric effect (MCE) in Ho2Pt2In was investigated via comprehensive inspection of magnetization isotherms collected near the magnetic phase transitions. The results revealed the second-order character of the transitions at TC and T1. The compound was found to exhibit the MCE characteristics fairly similar to those of typical magnetic refrigerant materials.Item High dimensional beam inference ii: inference of a perturbed hera beam from simulated visibility data(Oxford University Press, 2025) Bull, Philip; Wilensky, Michael J; Fagnoni, NicolasAccurate beam modelling is important in many radio astronomy applications. In this paper, we focus on beam modelling for 21-cm intensity mapping experiments using radio interferometers, though the techniques also apply to single dish experiments with small modifications. In 21-cm intensity mapping, beam models are usually determined from highly detailed electromagnetic simulations of the receiver system. However, these simulations are expensive, and therefore have limited ability to describe practical imperfections in the beam pattern. We present a fully analytic Bayesian inference framework to infer a beam pattern from the interferometric visibilities assuming a particular sky model and that the beam pattern for all elements is identical, allowing one to capture deviations from the ideal beam for relatively low computational cost. We represent the beam using a sparse Fourier-Bessel basis on a projection of the hemisphere to the unit disc, but the framework applies to any linear basis expansion of the primary beam. We test the framework on simulated visibilities from an unpolarized sky, ignoring mutual coupling of array elements. We successfully recover the simulated, perturbed power beam when the sky model is perfect. Briefly exploring sky model inaccuracies, we find that beam inferences are sensitive to them, so we suggest jointly modelling uncertainties in the sky and beam in related inference tasks.Item First β-delayed two-neutron spectroscopy of the r-process nucleus ^{134}In and observation of the i_{13/2} single-particle neutron State in ^{133}Sn(American Physical Society, 2025) Orce, José Nicolás; Dyszel, Peter; Grzywacz, RobertThis manuscript reports on the direct observation of a β-delayed two-neutron emission in a study of ^{134}In at the ISOLDE Decay Station using neutron spectroscopy. We also report on the first measurement in β^{-} decay of the long-sought 13/2^{+} excited state in ^{133}Sn, attributed to be the neutron single-particle i_{13/2} orbital. The observation of sequential neutron emission is used to extract the relative population of the i_{13/2} state, which was found to be much smaller than the predictions of the statistical model. The experiment was possible because of the innovative use of a neutron array with neutron discrimination and interaction tracking capabilities. This is the first study of the details of the two-neutron emission for a nucleus, which belongs to the r-process path. Understanding β-delayed two-neutron emission probabilities is essential to validate models used in astrophysical r-process nucleosynthesis calculations. Observing two-neutron emissions in β^{-} decay paves the way for new experiments to study energy and angular correlations for β-delayed multineutron emitters.Item VVV-WIT-13: An eruptive young star with cool molecular features(EDP Sciences, 2025) Lynas-Gray, Anthony Eugene; Guo, Zhen; Lucas, PhilipContext. Outburst phenomena are observed at different stages of stellar evolution, due to the enhancement of the mass accretion rate on protostars or even stellar merger events. In the case of a young stellar object (YSO), the episodic mass accretion event plays an important role in the pre-main-sequence stellar mass assembly. Here we investigate an infrared eruptive source (RA = 16:53:44.38; Dec = − 43:28:19.47), identified from the decade-long VISTA Variables in the Vía Láctea survey (VVV). We named this target after a group of variable sources discovered by VVV, as VVV-WIT-13, where WIT stands for ‘What is this?’, due to its unique photometric variation behaviour and the mysterious origin of the outburst. This target exhibited an outburst with a 5.7 mag amplitude in the K s -band, remained on its brightness plateau for 3.5 years, and then rapidly faded to its pre-eruptive brightness afterwards. Aims. Our aim is to reveal the variable nature and outburst origin of VVV-WIT-13 by presenting our follow-up photometric and spectroscopic observations along with theoretical models. Methods. We gathered photometric time series in both near- and mid-infrared wavelengths. We obtained near-infrared spectra during the outburst and decaying stages on XSHOOTER/VLT and FIRE/Magellan, and then fitted the detected molecular absorption features using models from ExoMol. We applied 2D numerical simulations to re-create the observables of the eruptive phenomenon. Results. We observe deep AlO absorption bands in the infrared spectra of VVV-WIT-13, during the outburst stage, along with other more common absorption bands (e.g. CO). Our best-fit model suggests a 600 K temperature of the AlO absorption band. In the decaying stage, the AlO bands disappeared, whilst broad blue-shifted H2 lines arose, a common indicator of stellar wind and outflow. The observational evidence suggests that the CO and TiO features originate from an outflow or a wind environment. Conclusions. We find that VVV-WIT-13 is an eruptive young star with instability occurring in the accretion disk. One favoured theoretical explanation of this event is a disrupted gas clump at a distance of 3 au from the source. If confirmed, this would be the first such event observed in real time.Item Machine-learning approaches for classifying star-forming galaxies and active galactic nuclei from MIGHTEE-detected radio sources in the COSMOS field(Oxford University Press, 2025) Silima, Walter; An, Fangxia; Vaccari, Mattia; Hussein, EslamRadio synchrotron emission originates from both massive star formation and black hole accretion, two processes that drive galaxy evolution. Efficient classification of sources dominated by either process is therefore essential for fully exploiting deep, wide-field extragalactic radio continuum surveys. In this study, we implement, optimize, and compare five widely used supervised machine-learning (ML) algorithms to classify radio sources detected in the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE)-COSMOS survey as star-forming galaxies (SFGs) and active galactic nuclei (AGNs). Training and test sets are constructed from conventionally classified MIGHTEE-COSMOS sources, and 18 physical parameters of the MIGHTEE-detected sources are evaluated as input features. As anticipated, our feature analyses rank the five parameters used in conventional classification as the most effective: the infrared–radio correlation parameter ($q_\mathrm{IR}$), the optical compactness morphology parameter (class_star), stellar mass, and two combined mid-infrared colours. By optimizing the ML models with these selected features and testing classifiers across various feature combinations, we find that model performance generally improves as additional features are incorporated. Overall, all five algorithms yield an F1-score (the harmonic mean of precision and recall) >90 per cent even when trained on only 20 per cent of the data set. Among them, the distance-based k-nearest neighbours classifier demonstrates the highest accuracy and stability, establishing it as a robust and effective method for classifying SFGs and AGNs in upcoming large radio continuum surveys.Item Cosmological multifield emulator(Springer Science and Business Media B.V., 2025) Andrianomena, Sambatra; Hassan, Sultan; Villaescusa-Navarro, FranciscoWe present the application of deep networks to learn the distribution of multiple large-scale fields, conditioned exclusively on cosmology while marginalizing over astrophysics. Our approach develops a generalized multifield emulator based purely on theoretical predictions from the state-of-the-art hydrodynamic simulations of the CAMELS project, without incorporating instrumental effects which limit the analysis to specifics of a particular large-scale survey design. To this end, we train a generative adversarial network to generate images composed of three different channels that represent gas density (Mgas), neutral hydrogen density (HI), and magnetic field amplitudes (B). We consider an unconstrained model and another scenario where the model is conditioned on the matter density Ωm and the amplitude of density fluctuations σ8. We find that the generated images exhibit great quality which is on a par with that of data, visually. Quantitatively, we find that our model generates maps whose statistical properties, quantified by probability distribution function (PDF) of pixel values and auto-power spectra, agree reasonably well up to the second moment with those of the real maps. The relative deviation between the PDFs is about 25% in both moments with larger deviations at the tails. The error between the two auto-power spectra is approximately less than 20% on scales larger than k=10h/Mpc, but becomes larger on smaller scales. Moreover, the mean and standard deviation of the cross-correlations between fields in all maps produced by the emulator are in good agreement with those of the real images, which indicates that our model generates instances whose maps in all three channels describe the same physical region. Furthermore, a CNN regressor, which has been trained to extract Ωm and σ8 from CAMELS multifield dataset, recovers the cosmology from the maps generated by our conditional model, achieving coefficient of determination values R2=0.96 and 0.83 corresponding to Ωm and σ8 respectively. This further demonstrates the great capability of the model to mimic CAMELS data. Our model can be useful for generating data, 1000 multiple images in ∼3 seconds as opposed to a simulation which takes days for one realization, that are required to analyze the information from upcoming multi-wavelength cosmological surveys.