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http://dx.doi.org/10.5303/JKAS.2014.47.5.195

VIMAP: AN INTERACTIVE PROGRAM PROVIDING RADIO SPECTRAL INDEX MAPS OF ACTIVE GALACTIC NUCLEI  

Kim, Jae-Young (Department of Physics and Astronomy, Seoul National University)
Trippe, Sascha (Department of Physics and Astronomy, Seoul National University)
Publication Information
Journal of The Korean Astronomical Society / v.47, no.5, 2014 , pp. 195-199 More about this Journal
Abstract
We present a GUI-based interactive Python program, VIMAP, which generates radio spectral index maps of active galactic nuclei (AGN) from Very Long Baseline Interferometry (VLBI) maps obtained at different frequencies. VIMAP is a handy tool for the spectral analysis of synchrotron emission from AGN jets, specifically of spectral index distributions, turn-over frequencies, and core-shifts. In general, the required accurate image alignment is difficult to achieve because of a loss of absolute spatial coordinate information during VLBI data reduction (self-calibration) and/or intrinsic variations of source structure as function of frequency. These issues are overcome by VIMAP which in turn is based on the two-dimensional cross-correlation algorithm of Croke & Gabuzda (2008). In this paper, we briefly review the problem of aligning VLBI AGN maps, describe the workflow of VIMAP, and present an analysis of archival VLBI maps of the active nucleus 3C 120.
Keywords
Galaxies: active; Radio continuum: galaxies; Methods: data analysis; numerical; Techniques: interferometric;
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Times Cited By KSCI : 3  (Citation Analysis)
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