Wavelet-based decomposition and analysis of structural patterns in astronomical images

Abstract

Context. Images of spatially resolved astrophysical objects contain a wealth of morphological and dynamical information, and effective extraction of this information is of paramount importance for understanding the physics and evolution of these objects. Algorithms and methods employed presently for this purpose (such as, for instance, Gaussian model fitting) often use simplified approaches for describing the structure of resolved objects. Aims. Automated (unsupervised) methods for structure decomposition and tracking of structural patterns are needed for this purpose, in order to be able to deal with the complexity of structure and large amount of data involved. Methods. A new Wavelet-based Image Segmentation and Evaluation (WISE) method is developed for multiscale decomposition, segmentation, and tracking of structural patterns in astronomical images. Results. The method is tested against simulated images of relativistic jets and applied to data from long-term monitoring of parsec- scale radio jets in 3C 273 and 3C 120. Working at its coarsest resolution, WISE reproduces exceptionally well the previous results of model fitting evaluation of the structure and kinematics in these jets. Extending the WISE structure analysis to the finer scales provides the first robust measurements of two-dimensional velocity fields in these jets and indicates that the velocity fields are likely to reflect the evolution of Kelvin-Hemlholtz instability developing the flow.

14 pages, Published in A&A

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Cited by in corpus (28)

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• Kinematics of the jet in M87 on scales of 100 -- 1000 Schwarzschild radii
• Horizon-Scale Lepton Acceleration in Jets: Explaining the Compact Radio Emission in M87
• Kinematics of the M87 jet in the collimation zone: gradual acceleration and velocity stratification
• Pilot KaVA monitoring on the M87 jet: confirming the inner jet structure and superluminal motions at sub-pc scales
• Fermi non-detections of four X-ray jet sources and implications for the IC/CMB mechanism
• Jet collimation and acceleration in the giant radio galaxy NGC 315
• Collimation of the relativistic jet in the quasar 3C 273
• Observations of the Structure and Dynamics of the Inner M87 Jet
• The TeV-emitting radio galaxy 3C 264. VLBI kinematics and SED modeling
• A multiband study and exploration of the radio wave - $\gamma$-ray connection in 3C 84
• Jet kinematics in the transversely stratified jet of 3C 84 A two-decade overview
• Multi-scale and Multi-directional VLBI Imaging with CLEAN
• Detection of an optical/UV jet/counterjet and Multiple Spectral Components in M84
• A detailed kinematic study of 3C 84 and its connection to Gamma-rays
• Dynamic and polarimetric VLBI imaging with a multiscalar approach
• Detection of multiple velocity components in partially overlapping emitting regions
• Observational Evidence to Support a Dense Ambient Medium Shaping the Jet in 3C 84
• The continuous wavelet derived by smoothing function and its application in cosmology
• Configuration of the global magnetic field in AGN parsec-scale jets
• Prospects of using closure traces directly for imaging in Very Long Baseline Interferometry
• SAND: An automated VLBI imaging and analysing pipeline - I. Stripping component trajectories
• Identifying Halos in Cosmological Simulations with Continuous Wavelet Analysis: The 2D Case
• $JetCurry$ I. Reconstructing Three-Dimensional Jet Geometry from Two-Dimensional Images
• CWTHF: Identifying Dark Matter Halos with Continuous Wavelet Transform
• Charge-Injection Device Imaging of Sirius with Contrast Ratios Greater than 1:26 Million
• DoG-HiT: A novel VLBI Multiscale Imaging Approach
• Very-Long Baseline Interferometry Imaging with Closure Invariants using Conditional Image Diffusion