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Separating SoFiA's Sources: An identification and separation module for SoFiA

Versteeg, M.J.F. (2016) Separating SoFiA's Sources: An identification and separation module for SoFiA. Bachelor's Thesis, Astronomy.

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Abstract

SoFiA (Source Finding Application) is a flexible piece of software that performs automated 3D detection and parametrization of sources in Hi data cubes. Sometimes, however, the Hi of galaxies that are close together might overlap. SoFiA is then unable to unambiguously assign the Hi regions to a galaxy and thus falsely identifies the galaxies as one source. This paper presents a new module for SoFiA, capable of identifying ambiguously assigned areas and separating those, in 2D, into their respective components. In order to do this, the module compares the objects found by SoFiA to optical information from an external database. By applying a watershed algorithm to a Gaussian-filtered moment-0 map of the data cube, an initial model is defined for each of the galaxies. If this method of model creation does not lead to a desired result, the module will use optical data to create rudimentary shapes to represent the galaxies. After determination the basic shapes, using either method, the model is then dilated until the SoFiA mask is completely filled, thus separating the mask into its component pieces. While the identification of shared sources is successful in 100% of the test cases, separation is only possible in 25% of the cases. In any case, even if additional separation is not required, the identification and separation module will provide the user with valuable information about their data.

Item Type: Thesis (Bachelor's Thesis)
Degree programme: Astronomy
Thesis type: Bachelor's Thesis
Language: English
Date Deposited: 15 Feb 2018 08:24
Last Modified: 15 Feb 2018 08:24
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/14428

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