Research

Antenna beam characterisation for the global 21cm experiment LEDA and its impact on signal model parameter reconstruction

Cosmic Dawn, the onset of star formation in the early universe, can in principle be studied via the 21cm transition of neutral hydrogen, for which a sky-averaged absorption signal, redshifted to MHz frequencies, is predicted to be {\it O}(10-100)\,mK. Detection requires separation of the 21cm signal from bright chromatic foreground emission due to Galactic structure, …

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Hybrid photometric redshifts for sources in the COSMOS and XMM-LSS fields

In this paper we present photometric redshifts for 2.7 million galaxies in the XMM-LSS and COSMOS fields, both with rich optical and near-infrared data from VISTA and HyperSuprimeCam. Both template fitting (using galaxy and Active Galactic Nuclei templates within LePhare) and machine learning (using GPz) methods are run on the aperture photometry of sources selected …

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First discoveries and localisations of Fast Radio Bursts with MeerTRAP: a real-time, commensal MeerKAT survey

We report on the discovery and localization of fast radio bursts (FRBs) from the MeerTRAP project, a commensal fast radio transient-detection programme at MeerKAT in South Africa. Our hybrid approach combines a coherent search with an average field-of-view of 0.4 deg2 with an incoherent search utilizing a field-of-view of ∼1.27 deg2 (both at 1284~MHz). Here, we present results on the …

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A structure function analysis of VST-COSMOS AGN

We present our sixth work in a series dedicated to variability studies of active galactic nuclei (AGN) based on the survey of the COSMOS field by the VLT Survey Telescope (VST). Its 54 r-band visits over 3.3 yr and single-visit depth of 24.6 r-band mag make this dataset a valuable scaled-down version that can help …

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The star-formation rates of QSOs

We examine the far-IR properties of a sample of 5391 optically selected QSOs in the 0.5<z<2.65 redshift range down to log[nuLnu,2500 (erg/s)]>44.7, using SPIRE data from Herschel-ATLAS. We split the sample in a grid of 74 luminosity-redshift bins and compute the average optical-infrared spectral energy distribution (SED) in each bin. By normalising an intrinsic AGN …

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Probabilistic learning for pulsar classification

In this work, we explore the possibility of using probabilistic learning to identify pulsar candidates. We make use of Deep Gaussian Process (DGP) and Deep Kernel Learning (DKL). Trained on a balanced training set in order to avoid the effect of class imbalance, the performance of the models, achieving relatively high probability of differentiating the …

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A void in the Hubble tension? The end of the line for the Hubble bubble

The Universe may feature large-scale inhomogeneities beyond the standard paradigm, implying that statistical homogeneity and isotropy may be reached only on much larger scales than the usually assumed ∼100 Mpc. This means that we are not necessarily typical observers and that the Copernican principle could be recovered only on super-Hubble scales. Here, we do not assume …

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CRC MSc AND PhD BURSARIES FOR 2023 

DEADLINE:  6 June 2022 The Centre for Radio Cosmology (CRC) at UWC is internationally recognised for its research in cosmology and galaxy evolution with MeerKAT, the Square Kilometre Array (SKA) and other telescopes (see astro.uwc.ac.za for further details). In  2022, the CRC research team includes 21 PhD/ MSc students and 11postdoctoral fellows. Postgraduate students at the CRC work in a friendly and highly active …

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A measurement of the Integrated Sachs-Wolfe Effect with the Rapid ASKAP Continuum Survey

The evolution of the gravitational potentials on large scales due to the accelerated expansion of the Universe is an important and independent probe of dark energy, known as the integrated Sachs-Wolfe (ISW) effect. We measure this ISW effect through cross-correlating the cosmic microwave background maps from the \textit{Planck} satellite with a radio continuum galaxy distribution …

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