English

Conditional Image Diffusion with Interferometric Closure Invariants: Independent EHT Imaging of Centaurus~A and 3C~279

Instrumentation and Methods for Astrophysics 2026-02-26 v1 Astrophysics of Galaxies High Energy Astrophysical Phenomena

Abstract

We present independent imaging analyses of Event Horizon Telescope (EHT) observations of the active galactic nuclei in radio galaxy Centaurus~A and quasar 3C~279 using Generative Deep learning Image Reconstruction with Closure Terms (GenDIReCT), a recently developed machine-learning framework built on conditional diffusion models that uses interferometric closure invariants as primary observables. For Centaurus~A, our reconstruction reveals two prominent emission ridges (80μ\simeq 80\,\muas each) along the jet sheath with a brightness ratio of 1.4±0.11.4\pm 0.1 and an opening angle of 12.3±0.312.3\pm 0.3~deg. For 3C~279, we identify three distinct components in the image, with the southern jet ejecta on sub-parsec scale exhibiting a proper motion of 4.6±1.0μ4.6\pm 1.0\,\muas over 5.39\approx 5.39 days away from the northern components, corresponding to an apparent superluminal velocity of 10±2\simeq 10\pm 2 times light speed. These measurements are consistent with those reported by the EHT Collaboration. The results are significant because we demonstrate that: (1) imaging from interferometric aperture synthesis data, especially in VLBI and most acutely in extremely sparse arrays like the EHT, remains a severely ill-posed and challenging inverse problem, yet closure invariants preserve robust morphological information that can strongly constrain structural features, and (2) more importantly, closure-invariant imaging largely avoids calibration systematics, thus providing a fundamentally independent view of spatial structure with very high angular resolution. The generative nature of GenDIReCT further allows us to sample and characterise clusters of plausible image solutions for each dataset. As a calibration-independent, generative imaging approach, GenDIReCT offers a robust and truly independent blind-imaging tool for current and future VLBI experiments.

Keywords

Cite

@article{arxiv.2602.21507,
  title  = {Conditional Image Diffusion with Interferometric Closure Invariants: Independent EHT Imaging of Centaurus~A and 3C~279},
  author = {Samuel Lai and Nithyanandan Thyagarajan and O. Ivy Wong and Foivos Diakogiannis},
  journal= {arXiv preprint arXiv:2602.21507},
  year   = {2026}
}

Comments

17 pages, 10 figures, 1 table, accepted by PASA

R2 v1 2026-07-01T10:50:58.400Z