Fluffy or bright? Using citizen science to find low-surface brightness and ultra-diffuse galaxies in the Fornax cluster

Seerden, Christiaan (2021) Fluffy or bright? Using citizen science to find low-surface brightness and ultra-diffuse galaxies in the Fornax cluster. Bachelor's Thesis, Astronomy.

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Abstract

In this thesis, we analyze over 200,000 classifications contributed by over 3,000 individual volunteer citizen scientists, of over 6,000 images from the Fornax Deep Survey, in an attempt to discover low-surface brightness galaxies in this cluster not found previously, or to confirm those found in previously created catalogues. We find that the users correctly classify at least 30 (and up to 48 depending on strictness of classification criteria) of the 232 low-surface brightness galaxies from a forthcoming catalogue of Fornax low-surface brightness galaxies. By performing our own visual classification, we find an additional 63 objects classified by the users as so-called ’fluffy’ galaxies, that were excluded from this forthcoming catalogue, but that from visual inspection do not show enough structure to be excluded from a catalogue of Fornax low-surface brightness galaxies. We find that objects with effective mean r-band surface brightness exceeding 25 mag/arcsec2 are never identified by the volunteers as galaxies, even though a significant fraction of low-surface brightness galaxies are at least this faint, or fainter, placing a limit on the viability of using user-contributed classifications in identifying low-surface brightness galaxies like those in Fornax. We believe that the accuracy of users could be increased through various improvements to the tutorial provided to them before they make their first classification.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Peletier, R.F. and Saifollahi, T.
Degree programme:	Astronomy
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	09 Jul 2021 11:07
Last Modified:	24 Nov 2021 10:32
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/25121

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