Multi-frequency synthesis algorithm based on Generalized Maximum Entropy Method. Application to 0954+658
arXiv:1106.3985 · doi:10.1111/j.1365-2966.2011.19280.x
Abstract
We propose the multi-frequency synthesis (MFS) algorithm with spectral correction of frequency-dependent source brightness distribution based on maximum entropy method. In order to take into account the spectral terms of n-th order in the Taylor expansion for the frequency-dependent brightness distribution, we use a generalized form of the maximum entropy method suitable for reconstruction of not only positive-definite functions, but also sign-variable ones. The proposed algorithm is aimed at producing both improved total intensity image and two-dimensional spectral index distribution over the source. We consider also the problem of frequency-dependent variation of the radio core positions of self-absorbed active galactic nuclei, which should be taken into account in a correct multi-frequency synthesis. First, the proposed MFS algorithm has been tested on simulated data and then applied to four-frequency synthesis imaging of the radio source 0954+658 from VLBA observational data obtained quasi-simultaneously at 5, 8, 15 and 22 GHz.
11 pages, 12 figures, 6 tables. Accepted for publication in MNRAS, 2011
References in corpus (5)
- Opacity in compact extragalactic radio sources and its effect on astrophysical and astrometric studies
- A Global 86GHz VLBI Survey of Compact Radio Sources
- Aligning VLBI Images of Active Galactic Nuclei at Different Frequencies
- Multifrequency VLBA study of the blazar S5 0716+714 during the active state in 2004 II. Large-scale jet kinematics and the comparison of the different methods of VLBI data imaging as applied to kinematic studies of AGN
- Reconstructing Images from Projections Using the Maximum-Entropy Method. Numerical Simulations of Low-Aspect Astrotomography