The Square Kilometre Array (SKA): publications

Peculiar radio-bright behaviour of the Galactic black hole transient 4U 1543-47 in the 2021-2023 outburst

(2025)

Authors:

X Zhang, W Yu, F Carotenuto, SE Motta, R Fender, JCA Miller-Jones, TD Russell, A Bahramian, P Woudt, AK Hughes, GR Sivakoff

Forty years of the Ellis–Baldwin test

Nature Reviews Physics Springer Nature 7:2 (2025) 68-70

Authors:

Nathan Secrest, Sebastian von Hausegger, Mohamed Rameez, Roya Mohayaee, Subir Sarkar

Abstract:

Modern cosmology is built on the assumption that the Universe is homogeneous and isotropic on large scales — but this is challenged by results of the Ellis–Baldwin test that show an unexplained anomaly in the distribution of distant galaxies and quasars.

IRIS: A Bayesian Approach for Image Reconstruction in Radio Interferometry with expressive Score-Based priors

ArXiv 2501.02473 (2025)

Authors:

Noé Dia, MJ Yantovski-Barth, Alexandre Adam, Micah Bowles, Laurence Perreault-Levasseur, Yashar Hezaveh, Anna Scaife

Long-term optical variations in Swift J1858.6–0814: evidence for ablation and comparisons to radio properties

Monthly Notices of the Royal Astronomical Society 91̽�� University Press (OUP) 536:4 (2025) 3421-3430

Authors:

L Rhodes, DM Russell, P Saikia, K Alabarta, J van den Eijnden, AH Knight, MC Baglio, F Lewis

X-Ray and Optical Polarization Aligned with the Radio Jet Ejecta in GX 339–4

The Astrophysical Journal Letters American Astronomical Society 978:2 (2025) L19

Authors:

G Mastroserio, B De Marco, MC Baglio, F Carotenuto, S Fabiani, TD Russell, F Capitanio, Y Cavecchi, S Motta, DM Russell, M Dovčiak, M Del Santo, K Alabarta, A Ambrifi, S Campana, P Casella, S Covino, G Illiano, E Kara, EV Lai, G Lodato, A Manca, I Mariani, A Marino

Abstract:

We present the first X-ray polarization measurements of GX 339–4. IXPE observed this source twice during its 2023–2024 outburst, once in the soft-intermediate state and again during a soft state. The observation taken during the intermediate state shows a significant (4σ) polarization degree PX = 1.3% ± 0.3% and polarization angle θX = −74° ± 7° only in the 3–8 keV band. FORS2 at the Very Large Telescope observed the source simultaneously, detecting optical polarization in the B, V, R, and I bands (between ∼0.1% and ∼0.7%), all roughly aligned with the X-ray polarization. We also detect a discrete jet knot from radio observations with the Australia Telescope Compact Array taken later in time; this knot would have been ejected from the system around the same time as the hard-to-soft X-ray state transition, and a bright radio flare occurred ∼3 months earlier. The proper motion of the jet knot provides a direct measurement of the jet orientation angle on the plane of the sky at the time of the ejection. We find that both the X-ray and optical polarization angles are aligned with the direction of the ballistic jet.

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