News

The bright end of the galaxy luminosity function at z≃7 from the VISTA VIDEO survey

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 …

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The HI in Ring Galaxies Survey (HI-RINGS) — Effects of the bar on the HI gas in ring galaxies

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 …

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Physics-informed neural networks in the recreation of hydrodynamic simulations from dark matter

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 …

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CEERS Key Paper VI: JWST/MIRI Uncovers a Large Population of Obscured AGN at High Redshifts

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 …

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Emulating radiation transport on cosmological scale using a denoising Unet

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 …

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Radio spectral properties at 150-5000MHz of star-forming galaxies in the ELAIS-N1 field

Distribution of radio spectral index at observed 150–610 MHz

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 …

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Invertible mapping between fields in CAMELS

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 …

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MIGHTEE-HI: Possible interactions with the galaxy NGC~895

The transformation and evolution of a galaxy is strongly influenced by interactions with its environment. Neutral hydrogen (HI) is an excellent way to trace these interactions. Here, we present HI observations of the spiral galaxy NGC~895, which was previously thought to be isolated. High-sensitivity HI observations from the MeerKAT large survey project MIGHTEE reveal possible …

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An HI story of galaxies in Abell 2626 and beyond

Context: To study the effects of environment on galaxies we use HI observations of galaxies in and around the cluster A2626. The cluster can effectively be divided in three different environments: the cluster itself, a group environment in the periphery of the cluster (we call it the Swarm) and substructure in the cluster itself. We …

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MIGHTEE: the nature of the radio-loud AGN population

We study the nature of the faint radio source population detected in the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) Early Science data in the COSMOS field, focusing on the properties of the radio-loud active galactic nuclei (AGN). Using the extensive multi-wavelength data available in the field, we are able to classify 88 per cent …

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