The first direct measurements of the HI intensity mapping power spectrum were recently made using the MeerKAT telescope. These measurements are on nonlinear scales, at redshifts 0.32 and 0.44. We develop a formalism for modelling small-scale power in redshift space, within the context of the mass-weighted HI halo model framework. This model is consistent with …
We present and compare several methods to mitigate time-correlated (1/f) noise within the HI intensity mapping component of the MeerKAT Large Area Synoptic Survey (MeerKLASS). By simulating scan strategies, the HI signal, white and correlated noise, we assess the ability of various data processing pipelines to recover the power spectrum of HI brightness temperature fluctuations. …
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 2023, the CRC research team includes 24 PhD/ MSc students and 11 postdoctoral fellows. Postgraduate students at the CRC work …
We have conducted a search for z≃7 Lyman break galaxies over 8.2 square degrees of near-infrared imaging from the VISTA Deep Extragalactic Observations (VIDEO) survey in the XMM-Newton – Large Scale Structure (XMM-LSS) and the Extended Chandra Deep Field South (ECDF-S) fields. Candidate galaxies were selected from a full photometric redshift analysis down to a Y+J depth of 25.3 …
We present a new high-resolution neutral atomic hydrogen (HI) survey of ring galaxies using the Australia Telescope Compact Array (ATCA). We target a sample of 24 ring galaxies from the Buta (1995) Southern Ring Galaxy Survey Catalogue in order to study the origin of resonance-, collisional- and interaction-driven ring galaxies. In this work, we present …
Physics-informed neural networks have emerged as a coherent framework for building predictive models that combine statistical patterns with domain knowledge. The underlying notion is to enrich the optimization loss function with known relationships to constrain the space of possible solutions. Hydrodynamic simulations are a core constituent of modern cosmology, while the required computations are both …
Mid-infrared observations are powerful in identifying heavily obscured Active Galactic Nuclei (AGN) which have weak emission in other wavelengths. The Mid-Infrared Instrument (MIRI) onboard JWST offers an excellent chance to perform such studies. We take advantage of the MIRI imaging data from the Cosmic Evolution Early Release Science Survey (CEERS) to investigate the AGN population …
Semi-numerical simulations are the leading candidates for evolving reionization on cosmological scales. These semi-numerical models are efficient in generating large-scale maps of the 21cm signal, but they are too slow to enable inference at the field level. We present different strategies to train a U-Net to accelerate these simulations. We derive the ionization field directly …
By combining high-sensitivity LOFAR 150 MHz, uGMRT 400 MHz, GMRT 610 MHz, and JVLA 5 GHz data in the ELAIS-N1 field, we study the radio spectral properties of radio-detected star-forming galaxies (SFGs) at observer-frame frequencies of 150-5000 MHz. We select ~ 3,500 SFGs that have both LOFAR 150 MHz and GMRT 610 MHz detections by …
We build a bijective mapping between different physical fields from hydrodynamic CAMELS simulations. We train a CycleGAN on three different setups: translating dark matter to neutral hydrogen (Mcdm-HI), mapping between dark matter and magnetic fields magnitude (Mcdm-B), and finally predicting magnetic fields magnitude from neutral hydrogen (HI-B). We assess the performance of the models using …
