Browsing by Author "Elson, Ed"

Now showing 1 - 5 of 5
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    MeerKAT-derived h i kinematics and the baryonic Tully–Fisher relation in the x-ray luminous cluster Abell 3408
    (Oxford University Press, 2025) Elson, Ed; Ndaliso, Xola; Blecher, Tariq
    Significant advances in observational capabilities are continuously transforming our understanding of the dense environment of galaxy clusters and its impact on individual galaxies. Discerning between the intrinsic and the externally induced properties of galaxies, including their gas kinematics, is a key diagnostic in the field of galaxy evolution. In this paper, we present MeerKAT HI spectral line observations of the redshift z ∼ 0.042 galaxy cluster Abell 3408. A total of 64 galaxies are detected in HI in this X-ray luminous galaxy cluster (LX ∼ 3 × 1043 erg s−1). We model the H I morphology and gas kinematics of the individual galaxies, using a semi-automated pipeline based on CANNUBI and pyBBarolo. The pipeline was developed and tested as part of this study. Of the 64 galaxies detected in the cluster, we successfully modelled 16, while the remaining galaxies exhibit disturbed HI morphologies, insufficient angular or velocity resolution. We combine the galaxies with converged kinematic fits with 67 field galaxies from the MeerKAT spectral line survey early science data (⟨z⟩= 0.0435) to produce a measurement of the baryonic Tully–Fisher relation (bTFr) that encompasses a broader range of environment and provides a useful comparison. We find a slope (α = 3.66+0.32−0.28) for this relation, which is consistent with that found from the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey bTFr derived from the same definition. Interestingly, HI detections of the Abell 3408 galaxy cluster galaxies are seen to extend the bTFr of the MIGHTEE sample, both in mass and velocity, despite their cluster environment.
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    MIGHTEE-H I: H I galaxy properties in the large-scale structure environment at z ∼ 0.37 from a stacking experiment
    (Oxford University Press, 2024) Sinigaglia, Francesco; Elson, Ed; Vaccari, Mattia
    We present the first measurement of H I mass of star-forming galaxies in different large scale structure environments from a blind survey at z ∼ 0.37. In particular, we carry out a spectral line stacking analysis considering 2875 spectra of colour-selected star-forming galaxies undetected in H I at 0.23 < z < 0.49 in the COSMOS field, extracted from the MIGHTEE-H I Early Science data cubes, acquired with the MeerKAT radio telescope. We stack galaxies belonging to different subsamples depending on three different definitions of large-scale structure environment: local galaxy overdensity, position inside the host dark matter halo (central, satellite, or isolated), and cosmic web type (field, filament, or knot). We first stack the full star-forming galaxy sample and find a robust H I detection yielding an average galaxy H I mass of MH I = (8.12 ± 0.75) × 109 M⊙ at ∼11.8σ. Next, we investigate the different subsamples finding a negligible difference in MH I as a function of the galaxy overdensity. We report an H I excess compared to the full sample in satellite galaxies (MH I = (11.31 ± 1.22) × 109, at ∼10.2σ) and in filaments (MH I = (11.62 ± 0.90) × 109. Conversely, we report non-detections for the central and knot galaxies subsamples, which appear to be H I-deficient.
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    Mock HI spectral line stacking experiments for large galaxy surveys
    (University of Western Cape, 2019) Tladi, Modisha; Elson, Ed; Maartens, Roy
    The study of neutral atomic hydrogen (HI) plays a vital role in improving the knowledge about galaxy evolution since HI serves as the raw fuel for star formation. However, the current knowledge about it is limited to the nearby Universe due to its intrinsic faintness and the inadequate sensitivities of the current radio telescopes.
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    New constraints on the evolution of the mh i−m⋆ scaling relation combining chiles and mightee-h i data
    (Institute of Physics, 2025) Elson, Ed; Vaccari, Mattia; Bianchetti, Alessandro
    The improved sensitivity of interferometric facilities to the 21 cm line of atomic hydrogen (H i) enables studies of its properties in galaxies beyond the local Universe. In this work, we perform a 21 cm line spectral stacking analysis combining the MeerKAT International GigaHertz Tiered Extragalactic Exploration and COSMOS H i Large Extra-galactic Survey surveys in the COSMOS field to derive a robust H i-stellar mass relation at z ≈ 0.36. In particular, by stacking thousands of star-forming galaxies subdivided into stellar mass bins, we optimize the signal-to-noise ratio of targets and derive mean H i masses in the different stellar mass intervals for the investigated galaxy population. We combine spectra from the two surveys, estimate H i masses, and derive the scaling relation log 10 M H I = ( 0.32 ± 0.04 ) log 10 M ⋆ + ( 6.65 ± 0.36 ) . Our findings indicate that galaxies at z ≈ 0.36 are H i richer than those at z ≈ 0 but H i poorer than those at z ≈ 1, with a slope consistent across redshift, suggesting that stellar mass does not significantly affect H i exchange mechanisms. We also observe a slower growth rate H i relative to the molecular gas, supporting the idea that the accretion of cold gas is slower than the rate of consumption of molecular gas to form stars. This study contributes to understanding the role of atomic gas in galaxy evolution and sets the stage for future development of the field in the upcoming Square Kilometre Array era.
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    A study of the nearby interacting galaxy pair NGC 1512/1510
    (University of Western Cape, 2020) Ndaliso, Xola; Elson, Ed; Glowacki, M.; Maartens, R.
    This work focuses on generating a new dynamical model of the nearby (9.5 Mpc) interacting galaxy system NGC 1512/1510. Neutral hydrogen (H i ) observations from the Australia Telescope Compact Array (ATCA) are used to model the dynamics of the main H i disk using two routines, the two and three-dimensional modeling techniques. For the two-dimensional modeling technique, we adopt ROTCUR which is based on fitting a tilted ring model onto the 2D velocity field of the galaxy. The three-dimensional modeling routine used is 3DBarolo, which is a recently developed algorithm of fitting 3D tilted ring model to the full data cube. We note that the 2D approach fails to model the inclination profile of NGC 1512. Thus, a new rotation curve is generated using the three-dimensional modeling routine only i.e. by fitting a 3D tilted ring model to the H i line data cube of NGC 1512/1510.