Andreea A. Vărăşteanu

arXiv2026

MIGHTEE-HI: HI catalogue of 293 sources for the COSMOS field and comparative study of 3-dimensional source finding methods

We present a catalogue of HI sources extracted from the MIGHTEE survey data cubes covering the COSMOS field. The catalogue contains 293 sources in the redshift range of 0.004 < z < 0.093. In addition to HI masses and velocity widths, the catalogue includes optical through near-infrared photometry and inferred stellar masses and star-formation rates. The quantity of sources in the HI catalogue acquired through untargeted source finding is greatly influenced by the source finding methods used. This study therefore also provides a well-characterised expected completeness of the detected sample of galaxies based on their properties, informing of any detection biases, inferred through a comparative study of different source finding algorithms. We have tested the performance of widely-used source finders: PyBDSF, ProFound and SoFiA, along with new source finder LESHI, focusing exclusively on HI source detection rather than source characterisation in the first instance. The source finders were tested by injecting a sample of simulated galaxies divided into narrow bins of mass, inclination and distance into a MeerKAT data cube. The results inform the source finding strategies for the MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) survey, as well as upcoming SKAO surveys.

astro-ph.GA↗

arXiv2025

MIGHTEE-HI: The radial acceleration relation with resolved stellar mass measurements

The radial acceleration relation (RAR) is a fundamental relation linking baryonic and dark matter in galaxies by relating the observed acceleration derived from dynamics to the one estimated from the baryonic mass. This relation exhibits small scatter, thus providing key constraints for models of galaxy formation and evolution -- allowing us to map the distribution of dark matter in galaxies -- as well as models of modified dynamics. However, it has only been extensively studied in the very local Universe with largely heterogeneous samples. We present a new measurement of the RAR, utilising a homogeneous sample of 19 HI-selected galaxies out to $z=0.08$. We introduce a novel approach of measuring resolved stellar masses using spectral energy distribution (SED) fitting across 10 photometric bands to determine the resolved mass-to-light ratio, which we show is essential for measuring the acceleration due to baryons in the low-acceleration regime. Our results reveal a tight RAR with a low-acceleration power-law slope of $\sim 0.5$, consistent with previous studies. Adopting a spatially varying mass-to-light ratio yields the tightest RAR with an intrinsic scatter of only $0.045 \pm 0.022$ dex, highlighting the importance of resolved stellar mass measurements in accurately characterising the gravitational contribution of the baryons in low-mass, gas-rich galaxies. We also find the first tentative evidence for redshift evolution in the acceleration scale, but more data will be required to confirm this. Adopting a more general MOND interpolating function, we find that our results ameliorate the tension between previous RAR analyses, the Solar System quadrupole and wide-binary test.

astro-ph.GA↗